Merge pull request #2759 from element-hq/feature/fga/permalink_timeline

Permalink timeline

appnav/src/main/kotlin/io/element/android/appnav/LoggedInFlowNode.kt

@@ -282,7 +282,7 @@ class LoggedInFlowNode @AssistedInject constructor(
                             is PermalinkData.RoomLink -> {
                                 backstack.push(
                                     NavTarget.Room(
-                                        data.roomIdOrAlias,
+                                        roomIdOrAlias = data.roomIdOrAlias,
                                         initialElement = RoomNavigationTarget.Messages(data.eventId),
                                         // TODO Use the viaParameters
                                     )

appnav/src/main/kotlin/io/element/android/appnav/room/RoomFlowNode.kt

@@ -83,7 +83,7 @@ class RoomFlowNode @AssistedInject constructor(
     data class Inputs(
         val roomIdOrAlias: RoomIdOrAlias,
         val roomDescription: Optional<RoomDescription>,
-        val initialElement: RoomNavigationTarget = RoomNavigationTarget.Messages(),
+        val initialElement: RoomNavigationTarget,
     ) : NodeInputs
 
     private val inputs: Inputs = inputs()
@@ -177,7 +177,10 @@ class RoomFlowNode @AssistedInject constructor(
             }
             is NavTarget.JoinedRoom -> {
                 val roomFlowNodeCallback = plugins<JoinedRoomLoadedFlowNode.Callback>()
-                val inputs = JoinedRoomFlowNode.Inputs(navTarget.roomId, initialElement = inputs.initialElement)
+                val inputs = JoinedRoomFlowNode.Inputs(
+                    roomId = navTarget.roomId,
+                    initialElement = inputs.initialElement
+                )
                 createNode<JoinedRoomFlowNode>(buildContext, plugins = listOf(inputs) + roomFlowNodeCallback)
             }
         }

appnav/src/main/kotlin/io/element/android/appnav/room/joined/JoinedRoomFlowNode.kt

@@ -69,7 +69,7 @@ class JoinedRoomFlowNode @AssistedInject constructor(
     ) {
     data class Inputs(
         val roomId: RoomId,
-        val initialElement: RoomNavigationTarget = RoomNavigationTarget.Messages(),
+        val initialElement: RoomNavigationTarget,
     ) : NodeInputs
 
     private val inputs: Inputs = inputs()
@@ -106,7 +106,10 @@ class JoinedRoomFlowNode @AssistedInject constructor(
                 val roomFlowNodeCallback = plugins<JoinedRoomLoadedFlowNode.Callback>()
                 val awaitRoomState = loadingRoomStateStateFlow.value
                 if (awaitRoomState is LoadingRoomState.Loaded) {
-                    val inputs = JoinedRoomLoadedFlowNode.Inputs(awaitRoomState.room, initialElement = inputs.initialElement)
+                    val inputs = JoinedRoomLoadedFlowNode.Inputs(
+                        room = awaitRoomState.room,
+                        initialElement = inputs.initialElement
+                    )
                     createNode<JoinedRoomLoadedFlowNode>(buildContext, plugins = listOf(inputs) + roomFlowNodeCallback)
                 } else {
                     loadingNode(buildContext, this::navigateUp)

appnav/src/main/kotlin/io/element/android/appnav/room/joined/JoinedRoomLoadedFlowNode.kt

@@ -84,7 +84,7 @@ class JoinedRoomLoadedFlowNode @AssistedInject constructor(
 
     data class Inputs(
         val room: MatrixRoom,
-        val initialElement: RoomNavigationTarget = RoomNavigationTarget.Messages(),
+        val initialElement: RoomNavigationTarget,
     ) : NodeInputs
 
     private val inputs: Inputs = inputs()

appnav/src/test/kotlin/io/element/android/appnav/JoinRoomLoadedFlowNodeTest.kt

@@ -27,6 +27,7 @@ import com.bumble.appyx.testing.junit4.util.MainDispatcherRule
 import com.bumble.appyx.testing.unit.common.helper.parentNodeTestHelper
 import com.google.common.truth.Truth.assertThat
 import io.element.android.appnav.di.RoomComponentFactory
+import io.element.android.appnav.room.RoomNavigationTarget
 import io.element.android.appnav.room.joined.JoinedRoomLoadedFlowNode
 import io.element.android.features.messages.api.MessagesEntryPoint
 import io.element.android.features.roomdetails.api.RoomDetailsEntryPoint
@@ -124,7 +125,7 @@ class JoinRoomLoadedFlowNodeTest {
         // GIVEN
         val room = FakeMatrixRoom()
         val fakeMessagesEntryPoint = FakeMessagesEntryPoint()
-        val inputs = JoinedRoomLoadedFlowNode.Inputs(room)
+        val inputs = JoinedRoomLoadedFlowNode.Inputs(room, RoomNavigationTarget.Messages())
         val roomFlowNode = createJoinedRoomLoadedFlowNode(
             plugins = listOf(inputs),
             messagesEntryPoint = fakeMessagesEntryPoint,
@@ -146,7 +147,7 @@ class JoinRoomLoadedFlowNodeTest {
         val room = FakeMatrixRoom()
         val fakeMessagesEntryPoint = FakeMessagesEntryPoint()
         val fakeRoomDetailsEntryPoint = FakeRoomDetailsEntryPoint()
-        val inputs = JoinedRoomLoadedFlowNode.Inputs(room)
+        val inputs = JoinedRoomLoadedFlowNode.Inputs(room, RoomNavigationTarget.Messages())
         val roomFlowNode = createJoinedRoomLoadedFlowNode(
             plugins = listOf(inputs),
             messagesEntryPoint = fakeMessagesEntryPoint,

changelog.d/2759.feature

@@ -0,0 +1 @@
+Handle permalink navigation to Events.

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/DefaultMessagesEntryPoint.kt

@@ -32,7 +32,7 @@ class DefaultMessagesEntryPoint @Inject constructor() : MessagesEntryPoint {
 
         return object : MessagesEntryPoint.NodeBuilder {
             override fun params(params: MessagesEntryPoint.Params): MessagesEntryPoint.NodeBuilder {
-                plugins += MessagesNode.Inputs(focusedEventId = params.focusedEventId)
+                plugins += MessagesFlowNode.Inputs(focusedEventId = params.focusedEventId)
                 return this
             }
 

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesFlowNode.kt

@@ -54,6 +54,7 @@ import io.element.android.libraries.architecture.BackstackWithOverlayBox
 import io.element.android.libraries.architecture.BaseFlowNode
 import io.element.android.libraries.architecture.NodeInputs
 import io.element.android.libraries.architecture.createNode
+import io.element.android.libraries.architecture.inputs
 import io.element.android.libraries.architecture.overlay.Overlay
 import io.element.android.libraries.architecture.overlay.operation.show
 import io.element.android.libraries.di.ApplicationContext
@@ -81,7 +82,7 @@ class MessagesFlowNode @AssistedInject constructor(
     private val createPollEntryPoint: CreatePollEntryPoint,
 ) : BaseFlowNode<MessagesFlowNode.NavTarget>(
     backstack = BackStack(
-        initialElement = NavTarget.Messages(plugins.filterIsInstance<Inputs>().firstOrNull()?.focusedEventId),
+        initialElement = NavTarget.Messages,
         savedStateMap = buildContext.savedStateMap,
     ),
     overlay = Overlay(
@@ -91,15 +92,14 @@ class MessagesFlowNode @AssistedInject constructor(
     plugins = plugins
 ) {
     data class Inputs(val focusedEventId: EventId?) : NodeInputs
+    private val inputs = inputs<Inputs>()
 
     sealed interface NavTarget : Parcelable {
         @Parcelize
         data object Empty : NavTarget
 
         @Parcelize
-        data class Messages(
-            val focusedEventId: EventId? = null,
-        ) : NavTarget
+        data object Messages : NavTarget
 
         @Parcelize
         data class MediaViewer(
@@ -191,10 +191,10 @@ class MessagesFlowNode @AssistedInject constructor(
                         ElementCallActivity.start(context, inputs)
                     }
                 }
-                val params = MessagesNode.Inputs(
-                    focusedEventId = navTarget.focusedEventId,
+                val inputs = MessagesNode.Inputs(
+                    focusedEventId = inputs.focusedEventId,
                 )
-                createNode<MessagesNode>(buildContext, listOf(callback, params))
+                createNode<MessagesNode>(buildContext, listOf(callback, inputs))
             }
             is NavTarget.MediaViewer -> {
                 val inputs = MediaViewerNode.Inputs(

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesNode.kt

@@ -19,6 +19,11 @@ package io.element.android.features.messages.impl
 import android.content.Context
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import com.bumble.appyx.core.lifecycle.subscribe
@@ -30,12 +35,15 @@ import dagger.assisted.Assisted
 import dagger.assisted.AssistedInject
 import io.element.android.anvilannotations.ContributesNode
 import io.element.android.features.messages.impl.attachments.Attachment
+import io.element.android.features.messages.impl.timeline.TimelineController
+import io.element.android.features.messages.impl.timeline.TimelineEvents
 import io.element.android.features.messages.impl.timeline.di.LocalTimelineItemPresenterFactories
 import io.element.android.features.messages.impl.timeline.di.TimelineItemPresenterFactories
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.libraries.androidutils.system.openUrlInExternalApp
 import io.element.android.libraries.androidutils.system.toast
 import io.element.android.libraries.architecture.NodeInputs
+import io.element.android.libraries.architecture.inputs
 import io.element.android.libraries.core.bool.orFalse
 import io.element.android.libraries.di.ApplicationContext
 import io.element.android.libraries.di.RoomScope
@@ -64,13 +72,15 @@ class MessagesNode @AssistedInject constructor(
     private val permalinkParser: PermalinkParser,
     @ApplicationContext
     private val context: Context,
+    private val timelineController: TimelineController,
 ) : Node(buildContext, plugins = plugins), MessagesNavigator {
     private val presenter = presenterFactory.create(this)
     private val callback = plugins<Callback>().firstOrNull()
 
-    // TODO Handle navigation to the Event
     data class Inputs(val focusedEventId: EventId?) : NodeInputs
 
+    private val inputs = inputs<Inputs>()
+
     interface Callback : Plugin {
         fun onRoomDetailsClicked()
         fun onEventClicked(event: TimelineItem.Event): Boolean
@@ -86,12 +96,14 @@ class MessagesNode @AssistedInject constructor(
         fun onJoinCallClicked(roomId: RoomId)
     }
 
-    init {
+    override fun onBuilt() {
+        super.onBuilt()
         lifecycle.subscribe(
             onCreate = {
                 analyticsService.capture(room.toAnalyticsViewRoom())
             },
             onDestroy = {
+                timelineController.close()
                 mediaPlayer.close()
             }
         )
@@ -116,6 +128,7 @@ class MessagesNode @AssistedInject constructor(
     private fun onLinkClicked(
         context: Context,
         url: String,
+        eventSink: (TimelineEvents) -> Unit,
     ) {
         when (val permalink = permalinkParser.parse(url)) {
             is PermalinkData.UserLink -> {
@@ -124,7 +137,7 @@ class MessagesNode @AssistedInject constructor(
                 callback?.onUserDataClicked(permalink.userId)
             }
             is PermalinkData.RoomLink -> {
-                handleRoomLinkClicked(permalink)
+                handleRoomLinkClicked(permalink, eventSink)
             }
             is PermalinkData.FallbackLink,
             is PermalinkData.RoomEmailInviteLink -> {
@@ -133,11 +146,11 @@ class MessagesNode @AssistedInject constructor(
         }
     }
 
-    private fun handleRoomLinkClicked(roomLink: PermalinkData.RoomLink) {
+    private fun handleRoomLinkClicked(roomLink: PermalinkData.RoomLink, eventSink: (TimelineEvents) -> Unit) {
         if (room.matches(roomLink.roomIdOrAlias)) {
-            if (roomLink.eventId != null) {
-                // TODO Handle navigation to the Event
-                context.toast("TODO Handle navigation to the Event ${roomLink.eventId}")
+            val eventId = roomLink.eventId
+            if (eventId != null) {
+                eventSink(TimelineEvents.FocusOnEvent(eventId))
             } else {
                 // Click on the same room, ignore
                 context.toast("Already viewing this room!")
@@ -189,12 +202,23 @@ class MessagesNode @AssistedInject constructor(
                 onEventClicked = this::onEventClicked,
                 onPreviewAttachments = this::onPreviewAttachments,
                 onUserDataClicked = this::onUserDataClicked,
-                onLinkClicked = { onLinkClicked(context, it) },
+                onLinkClicked = { onLinkClicked(context, it, state.timelineState.eventSink) },
                 onSendLocationClicked = this::onSendLocationClicked,
                 onCreatePollClicked = this::onCreatePollClicked,
                 onJoinCallClicked = this::onJoinCallClicked,
                 modifier = modifier,
             )
+
+            var focusedEventId by rememberSaveable {
+                mutableStateOf(inputs.focusedEventId)
+            }
+            LaunchedEffect(Unit) {
+                focusedEventId?.also { eventId ->
+                    state.timelineState.eventSink(TimelineEvents.FocusOnEvent(eventId))
+                }
+                // Reset the focused event id to null to avoid refocusing when restoring node.
+                focusedEventId = null
+            }
         }
     }
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesPresenter.kt

@@ -38,6 +38,7 @@ import io.element.android.features.messages.impl.actionlist.model.TimelineItemAc
 import io.element.android.features.messages.impl.messagecomposer.MessageComposerEvents
 import io.element.android.features.messages.impl.messagecomposer.MessageComposerPresenter
 import io.element.android.features.messages.impl.messagecomposer.MessageComposerState
+import io.element.android.features.messages.impl.timeline.TimelineController
 import io.element.android.features.messages.impl.timeline.TimelineEvents
 import io.element.android.features.messages.impl.timeline.TimelinePresenter
 import io.element.android.features.messages.impl.timeline.TimelineState
@@ -116,6 +117,7 @@ class MessagesPresenter @AssistedInject constructor(
     private val htmlConverterProvider: HtmlConverterProvider,
     @Assisted private val navigator: MessagesNavigator,
     private val buildMeta: BuildMeta,
+    private val timelineController: TimelineController,
 ) : Presenter<MessagesState> {
     private val timelinePresenter = timelinePresenterFactory.create(navigator = navigator)
 
@@ -185,10 +187,6 @@ class MessagesPresenter @AssistedInject constructor(
 
         val snackbarMessage by snackbarDispatcher.collectSnackbarMessageAsState()
 
-        LaunchedEffect(composerState.mode.relatedEventId) {
-            timelineState.eventSink(TimelineEvents.SetHighlightedEvent(composerState.mode.relatedEventId))
-        }
-
         val enableTextFormatting by appPreferencesStore.isRichTextEditorEnabledFlow().collectAsState(initial = true)
 
         var enableVoiceMessages by remember { mutableStateOf(false) }
@@ -290,8 +288,10 @@ class MessagesPresenter @AssistedInject constructor(
         emoji: String,
         eventId: EventId,
     ) = launch(dispatchers.io) {
-        room.toggleReaction(emoji, eventId)
-            .onFailure { Timber.e(it) }
+        timelineController.invokeOnCurrentTimeline {
+            toggleReaction(emoji, eventId)
+                .onFailure { Timber.e(it) }
+        }
     }
 
     private fun CoroutineScope.reinviteOtherUser(inviteProgress: MutableState<AsyncData<Unit>>) = launch(dispatchers.io) {

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesStateProvider.kt

@@ -106,6 +106,8 @@ fun aMessagesState(
     voiceMessageComposerState: VoiceMessageComposerState = aVoiceMessageComposerState(),
     timelineState: TimelineState = aTimelineState(
         timelineItems = aTimelineItemList(aTimelineItemTextContent()),
+        // Render a focused event for an event with sender information displayed
+        focusedEventIndex = 2,
     ),
     retrySendMenuState: RetrySendMenuState = aRetrySendMenuState(),
     readReceiptBottomSheetState: ReadReceiptBottomSheetState = aReadReceiptBottomSheetState(),

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesView.kt

@@ -382,20 +382,19 @@ private fun MessagesViewContent(
             },
             content = { paddingValues ->
                 TimelineView(
-                    modifier = Modifier.padding(paddingValues),
                     state = state.timelineState,
-                    roomName = state.roomName.dataOrNull(),
                     typingNotificationState = state.typingNotificationState,
-                    onMessageClicked = onMessageClicked,
-                    onMessageLongClicked = onMessageLongClicked,
                     onUserDataClicked = onUserDataClicked,
                     onLinkClicked = onLinkClicked,
+                    onMessageClicked = onMessageClicked,
+                    onMessageLongClicked = onMessageLongClicked,
                     onTimestampClicked = onTimestampClicked,
+                    onSwipeToReply = onSwipeToReply,
                     onReactionClicked = onReactionClicked,
                     onReactionLongClicked = onReactionLongClicked,
                     onMoreReactionsClicked = onMoreReactionsClicked,
                     onReadReceiptClick = onReadReceiptClick,
-                    onSwipeToReply = onSwipeToReply,
+                    modifier = Modifier.padding(paddingValues),
                     forceJumpToBottomVisibility = forceJumpToBottomVisibility,
                 )
             },

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/forward/ForwardMessagesPresenter.kt

@@ -29,7 +29,8 @@ import io.element.android.libraries.architecture.AsyncData
 import io.element.android.libraries.architecture.Presenter
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.RoomId
-import io.element.android.libraries.matrix.api.room.MatrixRoom
+import io.element.android.libraries.matrix.api.timeline.TimelineProvider
+import io.element.android.libraries.matrix.api.timeline.getActiveTimeline
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.toPersistentList
 import kotlinx.coroutines.CoroutineScope
@@ -37,8 +38,8 @@ import kotlinx.coroutines.launch
 
 class ForwardMessagesPresenter @AssistedInject constructor(
     @Assisted eventId: String,
-    private val room: MatrixRoom,
     private val matrixCoroutineScope: CoroutineScope,
+    private val timelineProvider: TimelineProvider,
 ) : Presenter<ForwardMessagesState> {
     private val eventId: EventId = EventId(eventId)
 
@@ -79,7 +80,7 @@ class ForwardMessagesPresenter @AssistedInject constructor(
         isForwardMessagesState: MutableState<AsyncData<ImmutableList<RoomId>>>,
     ) = launch {
         isForwardMessagesState.value = AsyncData.Loading()
-        room.forwardEvent(eventId, roomIds).fold(
+        timelineProvider.getActiveTimeline().forwardEvent(eventId, roomIds).fold(
             { isForwardMessagesState.value = AsyncData.Success(roomIds) },
             { isForwardMessagesState.value = AsyncData.Failure(it) }
         )

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/messagecomposer/MessageComposerPresenter.kt

@@ -38,6 +38,7 @@ import io.element.android.features.messages.impl.attachments.Attachment
 import io.element.android.features.messages.impl.attachments.preview.error.sendAttachmentError
 import io.element.android.features.messages.impl.mentions.MentionSuggestion
 import io.element.android.features.messages.impl.mentions.MentionSuggestionsProcessor
+import io.element.android.features.messages.impl.timeline.TimelineController
 import io.element.android.features.preferences.api.store.SessionPreferencesStore
 import io.element.android.libraries.architecture.Presenter
 import io.element.android.libraries.designsystem.utils.snackbar.SnackbarDispatcher
@@ -100,6 +101,7 @@ class MessageComposerPresenter @Inject constructor(
     private val permalinkParser: PermalinkParser,
     private val permalinkBuilder: PermalinkBuilder,
     permissionsPresenterFactory: PermissionsPresenter.Factory,
+    private val timelineController: TimelineController,
 ) : Presenter<MessageComposerState> {
     private val cameraPermissionPresenter = permissionsPresenterFactory.create(Manifest.permission.CAMERA)
     private var pendingEvent: MessageComposerEvents? = null
@@ -264,7 +266,9 @@ class MessageComposerPresenter @Inject constructor(
                         is MessageComposerMode.Quote -> null
                     }.let { relatedEventId ->
                         appCoroutineScope.launch {
-                            room.enterSpecialMode(relatedEventId)
+                            timelineController.invokeOnCurrentTimeline {
+                                enterSpecialMode(relatedEventId)
+                            }
                         }
                     }
                 }
@@ -386,16 +390,17 @@ class MessageComposerPresenter @Inject constructor(
             is MessageComposerMode.Edit -> {
                 val eventId = capturedMode.eventId
                 val transactionId = capturedMode.transactionId
-                room.editMessage(eventId, transactionId, message.markdown, message.html, mentions)
+                timelineController.invokeOnCurrentTimeline {
+                    editMessage(eventId, transactionId, message.markdown, message.html, mentions)
+                }
             }
 
             is MessageComposerMode.Quote -> TODO()
-            is MessageComposerMode.Reply -> room.replyMessage(
-                capturedMode.eventId,
-                message.markdown,
-                message.html,
-                mentions
-            )
+            is MessageComposerMode.Reply -> {
+                timelineController.invokeOnCurrentTimeline {
+                    replyMessage(capturedMode.eventId, message.markdown, message.html, mentions)
+                }
+            }
         }
         analyticsService.capture(
             Composer(

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineController.kt

@@ -0,0 +1,136 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline
+
+import com.squareup.anvil.annotations.ContributesBinding
+import io.element.android.libraries.di.RoomScope
+import io.element.android.libraries.di.SingleIn
+import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.room.MatrixRoom
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.Timeline
+import io.element.android.libraries.matrix.api.timeline.TimelineProvider
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.flatMapLatest
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.getAndUpdate
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.stateIn
+import java.io.Closeable
+import java.util.Optional
+import javax.inject.Inject
+
+/**
+ * This controller is responsible of using the right timeline to display messages and make associated actions.
+ * It can be focused on the live timeline or on a detached timeline (focusing an unknown event).
+ */
+@SingleIn(RoomScope::class)
+@ContributesBinding(RoomScope::class, boundType = TimelineProvider::class)
+class TimelineController @Inject constructor(
+    private val room: MatrixRoom,
+) : Closeable, TimelineProvider {
+    private val coroutineScope = CoroutineScope(SupervisorJob())
+
+    private val liveTimeline = flowOf(room.liveTimeline)
+    private val detachedTimeline = MutableStateFlow<Optional<Timeline>>(Optional.empty())
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    fun timelineItems(): Flow<List<MatrixTimelineItem>> {
+        return currentTimelineFlow.flatMapLatest { it.timelineItems }
+    }
+
+    fun isLive(): Flow<Boolean> {
+        return detachedTimeline.map { !it.isPresent }
+    }
+
+    suspend fun invokeOnCurrentTimeline(block: suspend (Timeline.() -> Any)) {
+        currentTimelineFlow.value.run {
+            block(this)
+        }
+    }
+
+    suspend fun focusOnEvent(eventId: EventId): Result<Unit> {
+        return room.timelineFocusedOnEvent(eventId)
+            .onFailure {
+                if (it is CancellationException) {
+                    throw it
+                }
+            }
+            .map { newDetachedTimeline ->
+                detachedTimeline.getAndUpdate { current ->
+                    if (current.isPresent) {
+                        current.get().close()
+                    }
+                    Optional.of(newDetachedTimeline)
+                }
+            }
+    }
+
+    /**
+     * Makes sure the controller is focused on the live timeline.
+     * This does close the detached timeline if any.
+     */
+    fun focusOnLive() {
+        closeDetachedTimeline()
+    }
+
+    private fun closeDetachedTimeline() {
+        detachedTimeline.getAndUpdate {
+            when {
+                it.isPresent -> {
+                    it.get().close()
+                    Optional.empty()
+                }
+                else -> Optional.empty()
+            }
+        }
+    }
+
+    override fun close() {
+        coroutineScope.cancel()
+        closeDetachedTimeline()
+    }
+
+    suspend fun paginate(direction: Timeline.PaginationDirection): Result<Boolean> {
+        return currentTimelineFlow.value.paginate(direction)
+            .onSuccess { hasReachedEnd ->
+                if (direction == Timeline.PaginationDirection.FORWARDS && hasReachedEnd) {
+                    focusOnLive()
+                }
+            }
+    }
+
+    private val currentTimelineFlow = combine(liveTimeline, detachedTimeline) { live, detached ->
+        when {
+            detached.isPresent -> detached.get()
+            else -> live
+        }
+    }.stateIn(coroutineScope, SharingStarted.Eagerly, room.liveTimeline)
+
+    override fun activeTimelineFlow(): StateFlow<Timeline> {
+        return currentTimelineFlow
+    }
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineEvents.kt

@@ -17,17 +17,21 @@
 package io.element.android.features.messages.impl.timeline
 
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.timeline.Timeline
 
 sealed interface TimelineEvents {
-    data object LoadMore : TimelineEvents
-    data class SetHighlightedEvent(val eventId: EventId?) : TimelineEvents
     data class OnScrollFinished(val firstIndex: Int) : TimelineEvents
+    data class FocusOnEvent(val eventId: EventId) : TimelineEvents
+    data object ClearFocusRequestState : TimelineEvents
+    data object JumpToLive : TimelineEvents
 
     /**
      * Events coming from a timeline item.
      */
     sealed interface EventFromTimelineItem : TimelineEvents
 
+    data class LoadMore(val direction: Timeline.PaginationDirection) : EventFromTimelineItem
+
     /**
      * Events coming from a poll item.
      */

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineItemIndexer.kt

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline
+
+import io.element.android.features.messages.impl.timeline.model.TimelineItem
+import io.element.android.libraries.di.RoomScope
+import io.element.android.libraries.di.SingleIn
+import io.element.android.libraries.matrix.api.core.EventId
+import timber.log.Timber
+import javax.inject.Inject
+
+@SingleIn(RoomScope::class)
+class TimelineItemIndexer @Inject constructor() {
+    private val timelineEventsIndexes = mutableMapOf<EventId, Int>()
+
+    fun isKnown(eventId: EventId): Boolean {
+        return timelineEventsIndexes.containsKey(eventId).also {
+            Timber.d("$eventId isKnown = $it")
+        }
+    }
+
+    fun indexOf(eventId: EventId): Int {
+        return (timelineEventsIndexes[eventId] ?: -1).also {
+            Timber.d("indexOf $eventId= $it")
+        }
+    }
+
+    fun process(timelineItems: List<TimelineItem>) {
+        Timber.d("process ${timelineItems.size} items")
+        timelineEventsIndexes.clear()
+        timelineItems.forEachIndexed { index, timelineItem ->
+            when (timelineItem) {
+                is TimelineItem.Event -> {
+                    processEvent(timelineItem, index)
+                }
+                is TimelineItem.GroupedEvents -> {
+                    timelineItem.events.forEach { event ->
+                        processEvent(event, index)
+                    }
+                }
+                else -> Unit
+            }
+        }
+    }
+
+    private fun processEvent(event: TimelineItem.Event, index: Int) {
+        if (event.eventId == null) return
+        timelineEventsIndexes[event.eventId] = index
+    }
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelinePresenter.kt

@@ -54,11 +54,9 @@ import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
-private const val BACK_PAGINATION_EVENT_LIMIT = 20
-private const val BACK_PAGINATION_PAGE_SIZE = 50
-
 class TimelinePresenter @AssistedInject constructor(
     private val timelineItemsFactory: TimelineItemsFactory,
+    private val timelineItemIndexer: TimelineItemIndexer,
     private val room: MatrixRoom,
     private val dispatchers: CoroutineDispatchers,
     private val appScope: CoroutineScope,
@@ -67,50 +65,62 @@ class TimelinePresenter @AssistedInject constructor(
     private val sendPollResponseAction: SendPollResponseAction,
     private val endPollAction: EndPollAction,
     private val sessionPreferencesStore: SessionPreferencesStore,
+    private val timelineController: TimelineController,
 ) : Presenter<TimelineState> {
     @AssistedFactory
     interface Factory {
         fun create(navigator: MessagesNavigator): TimelinePresenter
     }
 
-    private val timeline = room.timeline
-
     @Composable
     override fun present(): TimelineState {
         val localScope = rememberCoroutineScope()
-        val highlightedEventId: MutableState<EventId?> = rememberSaveable {
+        val focusedEventId: MutableState<EventId?> = rememberSaveable {
             mutableStateOf(null)
         }
+        val focusRequestState: MutableState<FocusRequestState> = remember {
+            mutableStateOf(FocusRequestState.None)
+        }
 
         val lastReadReceiptId = rememberSaveable { mutableStateOf<EventId?>(null) }
 
         val timelineItems by timelineItemsFactory.collectItemsAsState()
-        val paginationState by timeline.paginationState.collectAsState()
+
         val syncUpdateFlow = room.syncUpdateFlow.collectAsState()
 
         val userHasPermissionToSendMessage by room.canSendMessageAsState(type = MessageEventType.ROOM_MESSAGE, updateKey = syncUpdateFlow.value)
         val userHasPermissionToSendReaction by room.canSendMessageAsState(type = MessageEventType.REACTION, updateKey = syncUpdateFlow.value)
 
         val prevMostRecentItemId = rememberSaveable { mutableStateOf<String?>(null) }
-        val newItemState = remember { mutableStateOf(NewEventState.None) }
+
+        val newEventState = remember { mutableStateOf(NewEventState.None) }
 
         val isSendPublicReadReceiptsEnabled by sessionPreferencesStore.isSendPublicReadReceiptsEnabled().collectAsState(initial = true)
         val renderReadReceipts by sessionPreferencesStore.isRenderReadReceiptsEnabled().collectAsState(initial = true)
+        val isLive by timelineController.isLive().collectAsState(initial = true)
 
         fun handleEvents(event: TimelineEvents) {
             when (event) {
-                TimelineEvents.LoadMore -> localScope.paginateBackwards()
-                is TimelineEvents.SetHighlightedEvent -> highlightedEventId.value = event.eventId
-                is TimelineEvents.OnScrollFinished -> {
-                    if (event.firstIndex == 0) {
-                        newItemState.value = NewEventState.None
+                is TimelineEvents.LoadMore -> {
+                    localScope.launch {
+                        timelineController.paginate(direction = event.direction)
+                    }
+                }
+                is TimelineEvents.OnScrollFinished -> {
+                    if (isLive) {
+                        if (event.firstIndex == 0) {
+                            newEventState.value = NewEventState.None
+                        }
+                        println("## sendReadReceiptIfNeeded firstVisibleIndex: ${event.firstIndex}")
+                        appScope.sendReadReceiptIfNeeded(
+                            firstVisibleIndex = event.firstIndex,
+                            timelineItems = timelineItems,
+                            lastReadReceiptId = lastReadReceiptId,
+                            readReceiptType = if (isSendPublicReadReceiptsEnabled) ReceiptType.READ else ReceiptType.READ_PRIVATE,
+                        )
+                    } else {
+                        newEventState.value = NewEventState.None
                     }
-                    appScope.sendReadReceiptIfNeeded(
-                        firstVisibleIndex = event.firstIndex,
-                        timelineItems = timelineItems,
-                        lastReadReceiptId = lastReadReceiptId,
-                        readReceiptType = if (isSendPublicReadReceiptsEnabled) ReceiptType.READ else ReceiptType.READ_PRIVATE,
-                    )
                 }
                 is TimelineEvents.PollAnswerSelected -> appScope.launch {
                     sendPollResponseAction.execute(
@@ -123,28 +133,58 @@ class TimelinePresenter @AssistedInject constructor(
                         pollStartId = event.pollStartId,
                     )
                 }
-                is TimelineEvents.PollEditClicked ->
+                is TimelineEvents.PollEditClicked -> {
                     navigator.onEditPollClicked(event.pollStartId)
+                }
+                is TimelineEvents.FocusOnEvent -> localScope.launch {
+                    focusedEventId.value = event.eventId
+                    if (timelineItemIndexer.isKnown(event.eventId)) {
+                        val index = timelineItemIndexer.indexOf(event.eventId)
+                        focusRequestState.value = FocusRequestState.Cached(index)
+                    } else {
+                        focusRequestState.value = FocusRequestState.Fetching
+                        timelineController.focusOnEvent(event.eventId)
+                            .fold(
+                                onSuccess = {
+                                    focusRequestState.value = FocusRequestState.Fetched
+                                },
+                                onFailure = {
+                                    focusRequestState.value = FocusRequestState.Failure(it)
+                                }
+                            )
+                    }
+                }
+                is TimelineEvents.ClearFocusRequestState -> {
+                    focusRequestState.value = FocusRequestState.None
+                }
+                is TimelineEvents.JumpToLive -> {
+                    timelineController.focusOnLive()
+                }
             }
         }
 
         LaunchedEffect(timelineItems.size) {
-            computeNewItemState(timelineItems, prevMostRecentItemId, newItemState)
+            computeNewItemState(timelineItems, prevMostRecentItemId, newEventState)
+        }
+
+        LaunchedEffect(timelineItems.size, focusRequestState.value, focusedEventId.value) {
+            val currentFocusedEventId = focusedEventId.value
+            if (focusRequestState.value is FocusRequestState.Fetched && currentFocusedEventId != null) {
+                if (timelineItemIndexer.isKnown(currentFocusedEventId)) {
+                    val index = timelineItemIndexer.indexOf(currentFocusedEventId)
+                    focusRequestState.value = FocusRequestState.Cached(index)
+                }
+            }
         }
 
         LaunchedEffect(Unit) {
-            combine(timeline.timelineItems, room.membersStateFlow) { items, membersState ->
+            combine(timelineController.timelineItems(), room.membersStateFlow) { items, membersState ->
                 timelineItemsFactory.replaceWith(
                     timelineItems = items,
                     roomMembers = membersState.roomMembers().orEmpty()
                 )
                 items
             }
-                .onEach { timelineItems ->
-                    if (timelineItems.isEmpty()) {
-                        paginateBackwards()
-                    }
-                }
                 .onEach(redactedVoiceMessageManager::onEachMatrixTimelineItem)
                 .launchIn(this)
         }
@@ -152,6 +192,7 @@ class TimelinePresenter @AssistedInject constructor(
         val timelineRoomInfo by remember {
             derivedStateOf {
                 TimelineRoomInfo(
+                    name = room.displayName,
                     isDm = room.isDm,
                     userHasPermissionToSendMessage = userHasPermissionToSendMessage,
                     userHasPermissionToSendReaction = userHasPermissionToSendReaction,
@@ -160,11 +201,12 @@ class TimelinePresenter @AssistedInject constructor(
         }
         return TimelineState(
             timelineRoomInfo = timelineRoomInfo,
-            highlightedEventId = highlightedEventId.value,
-            paginationState = paginationState,
             timelineItems = timelineItems,
             renderReadReceipts = renderReadReceipts,
-            newEventState = newItemState.value,
+            newEventState = newEventState.value,
+            isLive = isLive,
+            focusedEventId = focusedEventId.value,
+            focusRequestState = focusRequestState.value,
             eventSink = { handleEvents(it) }
         )
     }
@@ -190,6 +232,7 @@ class TimelinePresenter @AssistedInject constructor(
             newMostRecentItem is TimelineItem.Event &&
             newMostRecentItem.origin != TimelineItemEventOrigin.PAGINATION &&
             newMostRecentItemId != prevMostRecentItemIdValue
+
         if (hasNewEvent) {
             val newMostRecentEvent = newMostRecentItem as? TimelineItem.Event
             // Scroll to bottom if the new event is from me, even if sent from another device
@@ -217,7 +260,7 @@ class TimelinePresenter @AssistedInject constructor(
             val eventId = getLastEventIdBeforeOrAt(firstVisibleIndex, timelineItems)
             if (eventId != null && eventId != lastReadReceiptId.value) {
                 lastReadReceiptId.value = eventId
-                timeline.sendReadReceipt(eventId = eventId, receiptType = readReceiptType)
+                room.liveTimeline.sendReadReceipt(eventId = eventId, receiptType = readReceiptType)
             }
         }
     }
@@ -231,8 +274,4 @@ class TimelinePresenter @AssistedInject constructor(
         }
         return null
     }
-
-    private fun CoroutineScope.paginateBackwards() = launch {
-        timeline.paginateBackwards(BACK_PAGINATION_EVENT_LIMIT, BACK_PAGINATION_PAGE_SIZE)
-    }
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineState.kt

@@ -20,7 +20,6 @@ import androidx.compose.runtime.Immutable
 import io.element.android.features.messages.impl.timeline.model.NewEventState
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.libraries.matrix.api.core.EventId
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
 import kotlinx.collections.immutable.ImmutableList
 
 @Immutable
@@ -28,15 +27,28 @@ data class TimelineState(
     val timelineItems: ImmutableList<TimelineItem>,
     val timelineRoomInfo: TimelineRoomInfo,
     val renderReadReceipts: Boolean,
-    val highlightedEventId: EventId?,
-    val paginationState: MatrixTimeline.PaginationState,
     val newEventState: NewEventState,
-    val eventSink: (TimelineEvents) -> Unit
-)
+    val isLive: Boolean,
+    val focusedEventId: EventId?,
+    val focusRequestState: FocusRequestState,
+    val eventSink: (TimelineEvents) -> Unit,
+) {
+    val hasAnyEvent = timelineItems.any { it is TimelineItem.Event }
+}
+
+@Immutable
+sealed interface FocusRequestState {
+    data object None : FocusRequestState
+    data class Cached(val index: Int) : FocusRequestState
+    data object Fetching : FocusRequestState
+    data object Fetched : FocusRequestState
+    data class Failure(val throwable: Throwable) : FocusRequestState
+}
 
 @Immutable
 data class TimelineRoomInfo(
     val isDm: Boolean,
+    val name: String?,
     val userHasPermissionToSendMessage: Boolean,
     val userHasPermissionToSendReaction: Boolean,
 )

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt

@@ -35,7 +35,6 @@ import io.element.android.libraries.designsystem.components.avatar.AvatarSize
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
 import io.element.android.libraries.matrix.api.timeline.item.TimelineItemDebugInfo
 import io.element.android.libraries.matrix.api.timeline.item.event.LocalEventSendState
 import kotlinx.collections.immutable.ImmutableList
@@ -47,32 +46,22 @@ import kotlin.random.Random
 
 fun aTimelineState(
     timelineItems: ImmutableList<TimelineItem> = persistentListOf(),
-    paginationState: MatrixTimeline.PaginationState = aPaginationState(),
     renderReadReceipts: Boolean = false,
     timelineRoomInfo: TimelineRoomInfo = aTimelineRoomInfo(),
+    focusedEventIndex: Int = -1,
+    isLive: Boolean = true,
     eventSink: (TimelineEvents) -> Unit = {},
 ) = TimelineState(
     timelineItems = timelineItems,
     timelineRoomInfo = timelineRoomInfo,
-    paginationState = paginationState,
     renderReadReceipts = renderReadReceipts,
-    highlightedEventId = null,
     newEventState = NewEventState.None,
+    isLive = isLive,
+    focusedEventId = timelineItems.filterIsInstance<TimelineItem.Event>().getOrNull(focusedEventIndex)?.eventId,
+    focusRequestState = FocusRequestState.None,
     eventSink = eventSink,
 )
 
-fun aPaginationState(
-    isBackPaginating: Boolean = false,
-    hasMoreToLoadBackwards: Boolean = true,
-    beginningOfRoomReached: Boolean = false,
-): MatrixTimeline.PaginationState {
-    return MatrixTimeline.PaginationState(
-        isBackPaginating = isBackPaginating,
-        hasMoreToLoadBackwards = hasMoreToLoadBackwards,
-        beginningOfRoomReached = beginningOfRoomReached,
-    )
-}
-
 internal fun aTimelineItemList(content: TimelineItemEventContent): ImmutableList<TimelineItem> {
     return persistentListOf(
         // 3 items (First Middle Last) with isMine = false
@@ -235,10 +224,12 @@ internal fun aGroupedEvents(
 }
 
 internal fun aTimelineRoomInfo(
+    name: String = "Room name",
     isDm: Boolean = false,
     userHasPermissionToSendMessage: Boolean = true,
 ) = TimelineRoomInfo(
     isDm = isDm,
+    name = name,
     userHasPermissionToSendMessage = userHasPermissionToSendMessage,
     userHasPermissionToSendReaction = true,
 )

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineView.kt

@@ -55,10 +55,9 @@ import androidx.compose.ui.unit.dp
 import io.element.android.compound.theme.ElementTheme
 import io.element.android.compound.tokens.generated.CompoundIcons
 import io.element.android.features.messages.impl.timeline.components.TimelineItemRow
-import io.element.android.features.messages.impl.timeline.components.virtual.TimelineItemRoomBeginningView
-import io.element.android.features.messages.impl.timeline.components.virtual.TimelineLoadingMoreIndicator
 import io.element.android.features.messages.impl.timeline.di.LocalTimelineItemPresenterFactories
 import io.element.android.features.messages.impl.timeline.di.aFakeTimelineItemPresenterFactories
+import io.element.android.features.messages.impl.timeline.focus.FocusRequestStateView
 import io.element.android.features.messages.impl.timeline.model.NewEventState
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEventContent
@@ -74,12 +73,12 @@ import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.ui.strings.CommonStrings
 import kotlinx.coroutines.launch
+import kotlin.math.abs
 
 @Composable
 fun TimelineView(
     state: TimelineState,
     typingNotificationState: TypingNotificationState,
-    roomName: String?,
     onUserDataClicked: (UserId) -> Unit,
     onLinkClicked: (String) -> Unit,
     onMessageClicked: (TimelineItem.Event) -> Unit,
@@ -93,8 +92,8 @@ fun TimelineView(
     modifier: Modifier = Modifier,
     forceJumpToBottomVisibility: Boolean = false
 ) {
-    fun onReachedLoadMore() {
-        state.eventSink(TimelineEvents.LoadMore)
+    fun clearFocusRequestState() {
+        state.eventSink(TimelineEvents.ClearFocusRequestState)
     }
 
     fun onScrollFinishedAt(firstVisibleIndex: Int) {
@@ -109,9 +108,8 @@ fun TimelineView(
         accessibilityManager.isTouchExplorationEnabled.not()
     }
 
-    @Suppress("UNUSED_PARAMETER")
     fun inReplyToClicked(eventId: EventId) {
-        // TODO implement this logic once we have support to 'jump to event X' in sliding sync
+        state.eventSink(TimelineEvents.FocusOnEvent(eventId))
     }
 
     // Animate alpha when timeline is first displayed, to avoid flashes or glitching when viewing rooms
@@ -123,8 +121,10 @@ fun TimelineView(
                 reverseLayout = useReverseLayout,
                 contentPadding = PaddingValues(vertical = 8.dp),
             ) {
-                item {
-                    TypingNotificationView(state = typingNotificationState)
+                if (state.isLive) {
+                    item {
+                        TypingNotificationView(state = typingNotificationState)
+                    }
                 }
                 items(
                     items = state.timelineItems,
@@ -137,7 +137,7 @@ fun TimelineView(
                         renderReadReceipts = state.renderReadReceipts,
                         isLastOutgoingMessage = (timelineItem as? TimelineItem.Event)?.isMine == true &&
                             state.timelineItems.first().identifier() == timelineItem.identifier(),
-                        highlightedItem = state.highlightedEventId?.value,
+                        focusedEventId = state.focusedEventId,
                         onClick = onMessageClicked,
                         onLongClick = onMessageLongClicked,
                         onUserDataClick = onUserDataClicked,
@@ -152,28 +152,23 @@ fun TimelineView(
                         onSwipeToReply = onSwipeToReply,
                     )
                 }
-                if (state.paginationState.hasMoreToLoadBackwards) {
-                    // Do not use key parameter to avoid wrong positioning
-                    item(contentType = "TimelineLoadingMoreIndicator") {
-                        TimelineLoadingMoreIndicator()
-                        LaunchedEffect(Unit) {
-                            onReachedLoadMore()
-                        }
-                    }
-                }
-                if (state.paginationState.beginningOfRoomReached && !state.timelineRoomInfo.isDm) {
-                    item(contentType = "BeginningOfRoomReached") {
-                        TimelineItemRoomBeginningView(roomName = roomName)
-                    }
-                }
             }
 
+            FocusRequestStateView(
+                focusRequestState = state.focusRequestState,
+                onClearFocusRequestState = ::clearFocusRequestState
+            )
+
             TimelineScrollHelper(
-                isTimelineEmpty = state.timelineItems.isEmpty(),
+                hasAnyEvent = state.hasAnyEvent,
                 lazyListState = lazyListState,
                 forceJumpToBottomVisibility = forceJumpToBottomVisibility,
                 newEventState = state.newEventState,
-                onScrollFinishedAt = ::onScrollFinishedAt
+                isLive = state.isLive,
+                focusRequestState = state.focusRequestState,
+                onScrollFinishedAt = ::onScrollFinishedAt,
+                onClearFocusRequestState = ::clearFocusRequestState,
+                onJumpToLive = { state.eventSink(TimelineEvents.JumpToLive) },
             )
         }
     }
@@ -181,17 +176,21 @@ fun TimelineView(
 
 @Composable
 private fun BoxScope.TimelineScrollHelper(
-    isTimelineEmpty: Boolean,
+    hasAnyEvent: Boolean,
     lazyListState: LazyListState,
     newEventState: NewEventState,
+    isLive: Boolean,
     forceJumpToBottomVisibility: Boolean,
+    focusRequestState: FocusRequestState,
+    onClearFocusRequestState: () -> Unit,
     onScrollFinishedAt: (Int) -> Unit,
+    onJumpToLive: () -> Unit,
 ) {
     val coroutineScope = rememberCoroutineScope()
     val isScrollFinished by remember { derivedStateOf { !lazyListState.isScrollInProgress } }
     val canAutoScroll by remember {
         derivedStateOf {
-            lazyListState.firstVisibleItemIndex < 3
+            lazyListState.firstVisibleItemIndex < 3 && isLive
         }
     }
 
@@ -205,16 +204,36 @@ private fun BoxScope.TimelineScrollHelper(
         }
     }
 
+    fun jumpToBottom() {
+        if (isLive) {
+            scrollToBottom()
+        } else {
+            onJumpToLive()
+        }
+    }
+
+    val latestOnClearFocusRequestState by rememberUpdatedState(onClearFocusRequestState)
+    LaunchedEffect(focusRequestState) {
+        if (focusRequestState is FocusRequestState.Cached) {
+            if (abs(lazyListState.firstVisibleItemIndex - focusRequestState.index) < 10) {
+                lazyListState.animateScrollToItem(focusRequestState.index)
+            } else {
+                lazyListState.scrollToItem(focusRequestState.index)
+            }
+            latestOnClearFocusRequestState()
+        }
+    }
+
     LaunchedEffect(canAutoScroll, newEventState) {
-        val shouldAutoScroll = isScrollFinished && (canAutoScroll || newEventState == NewEventState.FromMe)
-        if (shouldAutoScroll) {
+        val shouldScrollToBottom = isScrollFinished && (canAutoScroll || newEventState == NewEventState.FromMe)
+        if (shouldScrollToBottom) {
             scrollToBottom()
         }
     }
 
     val latestOnScrollFinishedAt by rememberUpdatedState(onScrollFinishedAt)
-    LaunchedEffect(isScrollFinished, isTimelineEmpty) {
-        if (isScrollFinished && !isTimelineEmpty) {
+    LaunchedEffect(isScrollFinished, hasAnyEvent) {
+        if (isScrollFinished && hasAnyEvent) {
             // Notify the parent composable about the first visible item index when scrolling finishes
             latestOnScrollFinishedAt(lazyListState.firstVisibleItemIndex)
         }
@@ -222,11 +241,11 @@ private fun BoxScope.TimelineScrollHelper(
 
     JumpToBottomButton(
         // Use inverse of canAutoScroll otherwise we might briefly see the before the scroll animation is triggered
-        isVisible = !canAutoScroll || forceJumpToBottomVisibility,
+        isVisible = !canAutoScroll || forceJumpToBottomVisibility || !isLive,
         modifier = Modifier
             .align(Alignment.BottomEnd)
             .padding(end = 24.dp, bottom = 12.dp),
-        onClick = ::scrollToBottom,
+        onClick = { jumpToBottom() },
     )
 }
 
@@ -271,18 +290,20 @@ internal fun TimelineViewPreview(
         LocalTimelineItemPresenterFactories provides aFakeTimelineItemPresenterFactories(),
     ) {
         TimelineView(
-            state = aTimelineState(timelineItems),
-            roomName = null,
+            state = aTimelineState(
+                timelineItems = timelineItems,
+                focusedEventIndex = 0,
+            ),
             typingNotificationState = aTypingNotificationState(),
-            onMessageClicked = {},
-            onTimestampClicked = {},
             onUserDataClicked = {},
             onLinkClicked = {},
+            onMessageClicked = {},
             onMessageLongClicked = {},
+            onTimestampClicked = {},
+            onSwipeToReply = {},
             onReactionClicked = { _, _ -> },
             onReactionLongClicked = { _, _ -> },
             onMoreReactionsClicked = {},
-            onSwipeToReply = {},
             onReadReceiptClick = {},
             forceJumpToBottomVisibility = true,
         )

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemEventRow.kt

@@ -24,7 +24,6 @@ import androidx.compose.foundation.gestures.Orientation
 import androidx.compose.foundation.gestures.draggable
 import androidx.compose.foundation.interaction.MutableInteractionSource
 import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Arrangement.spacedBy
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
@@ -93,7 +92,9 @@ import io.element.android.features.messages.impl.timeline.model.event.TimelineIt
 import io.element.android.features.messages.impl.timeline.model.event.aTimelineItemImageContent
 import io.element.android.features.messages.impl.timeline.model.event.aTimelineItemTextContent
 import io.element.android.features.messages.impl.timeline.model.event.canBeRepliedTo
+import io.element.android.features.messages.impl.timeline.model.eventId
 import io.element.android.features.messages.impl.timeline.model.metadata
+import io.element.android.libraries.designsystem.atomic.atoms.PlaceholderAtom
 import io.element.android.libraries.designsystem.colors.AvatarColorsProvider
 import io.element.android.libraries.designsystem.components.EqualWidthColumn
 import io.element.android.libraries.designsystem.components.avatar.Avatar
@@ -146,7 +147,7 @@ fun TimelineItemEventRow(
     }
 
     fun inReplyToClicked() {
-        val inReplyToEventId = event.inReplyTo?.eventId ?: return
+        val inReplyToEventId = event.inReplyTo?.eventId() ?: return
         inReplyToClick(inReplyToEventId)
     }
 
@@ -417,7 +418,6 @@ private fun MessageSenderInformation(
 private fun MessageEventBubbleContent(
     event: TimelineItem.Event,
     onMessageLongClick: () -> Unit,
-    @Suppress("UNUSED_PARAMETER")
     inReplyToClick: () -> Unit,
     onTimestampClicked: () -> Unit,
     onLinkClicked: (String) -> Unit,
@@ -437,7 +437,7 @@ private fun MessageEventBubbleContent(
     ) {
         Row(
             modifier = modifier,
-            horizontalArrangement = spacedBy(4.dp, Alignment.Start),
+            horizontalArrangement = Arrangement.spacedBy(4.dp, Alignment.Start),
             verticalAlignment = Alignment.CenterVertically,
         ) {
             Icon(
@@ -565,16 +565,30 @@ private fun MessageEventBubbleContent(
         }
         val inReplyTo = @Composable { inReplyTo: InReplyToDetails ->
             val topPadding = if (showThreadDecoration) 0.dp else 8.dp
-            ReplyToContent(
-                senderId = inReplyTo.senderId,
-                senderProfile = inReplyTo.senderProfile,
-                metadata = inReplyTo.metadata(),
-                modifier = Modifier
-                    .padding(top = topPadding, start = 8.dp, end = 8.dp)
-                    .clip(RoundedCornerShape(6.dp))
+            val inReplyToModifier = Modifier
+                .padding(top = topPadding, start = 8.dp, end = 8.dp)
+                .clip(RoundedCornerShape(6.dp))
                 // FIXME when a node is clickable, its contents won't be added to the semantics tree of its parent
-//                    .clickable(enabled = true, onClick = inReplyToClick)
-            )
+                .clickable(onClick = inReplyToClick)
+            when (inReplyTo) {
+                is InReplyToDetails.Ready -> {
+                    ReplyToContent(
+                        senderId = inReplyTo.senderId,
+                        senderProfile = inReplyTo.senderProfile,
+                        metadata = inReplyTo.metadata(),
+                        modifier = inReplyToModifier,
+                    )
+                }
+                is InReplyToDetails.Error ->
+                    ReplyToErrorContent(
+                        data = inReplyTo,
+                        modifier = inReplyToModifier,
+                    )
+                is InReplyToDetails.Loading ->
+                    ReplyToLoadingContent(
+                        modifier = inReplyToModifier,
+                    )
+            }
         }
         if (inReplyToDetails != null) {
             // Use SubComposeLayout only if necessary as it can have consequences on the performance.
@@ -584,7 +598,7 @@ private fun MessageEventBubbleContent(
                 contentWithTimestamp()
             }
         } else {
-            Column(modifier = modifier, verticalArrangement = spacedBy(8.dp)) {
+            Column(modifier = modifier, verticalArrangement = Arrangement.spacedBy(8.dp)) {
                 threadDecoration()
                 contentWithTimestamp()
             }
@@ -652,6 +666,44 @@ private fun ReplyToContent(
     }
 }
 
+@Composable
+private fun ReplyToLoadingContent(
+    modifier: Modifier = Modifier,
+) {
+    val paddings = PaddingValues(horizontal = 12.dp, vertical = 4.dp)
+    Row(
+        modifier
+            .background(MaterialTheme.colorScheme.surface)
+            .padding(paddings)
+    ) {
+        Column(verticalArrangement = Arrangement.spacedBy(4.dp)) {
+            PlaceholderAtom(width = 80.dp, height = 12.dp)
+            PlaceholderAtom(width = 140.dp, height = 14.dp)
+        }
+    }
+}
+
+@Composable
+private fun ReplyToErrorContent(
+    data: InReplyToDetails.Error,
+    modifier: Modifier = Modifier,
+) {
+    val paddings = PaddingValues(horizontal = 12.dp, vertical = 4.dp)
+    Row(
+        modifier
+            .background(MaterialTheme.colorScheme.surface)
+            .padding(paddings)
+    ) {
+        Text(
+            text = data.message,
+            style = ElementTheme.typography.fontBodyMdRegular,
+            color = MaterialTheme.colorScheme.error,
+            maxLines = 2,
+            overflow = TextOverflow.Ellipsis,
+        )
+    }
+}
+
 @Composable
 private fun ReplyToContentText(metadata: InReplyToMetadata?) {
     val text = when (metadata) {

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemEventRowWithReplyOtherPreview.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline.components
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.tooling.preview.PreviewParameter
+import io.element.android.features.messages.impl.timeline.model.InReplyToDetails
+import io.element.android.libraries.designsystem.preview.ElementPreview
+import io.element.android.libraries.designsystem.preview.PreviewsDayNight
+import io.element.android.libraries.matrix.api.core.EventId
+
+@PreviewsDayNight
+@Composable
+internal fun TimelineItemEventRowWithReplyOtherPreview(
+    @PreviewParameter(InReplyToDetailsOtherProvider::class) inReplyToDetails: InReplyToDetails,
+) = ElementPreview {
+    TimelineItemEventRowWithReplyContentToPreview(inReplyToDetails)
+}
+
+class InReplyToDetailsOtherProvider : InReplyToDetailsProvider() {
+    override val values: Sequence<InReplyToDetails>
+        get() = sequenceOf(
+            InReplyToDetails.Loading(eventId = EventId("\$anEventId")),
+            InReplyToDetails.Error(eventId = EventId("\$anEventId"), message = "An error message."),
+        )
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemEventRowWithReplyPreview.kt

@@ -170,7 +170,7 @@ open class InReplyToDetailsProvider : PreviewParameterProvider<InReplyToDetails>
     protected fun aInReplyToDetails(
         eventContent: EventContent,
         displayNameAmbiguous: Boolean = false,
-    ) = InReplyToDetails(
+    ) = InReplyToDetails.Ready(
         eventId = EventId("\$event"),
         eventContent = eventContent,
         senderId = UserId("@Sender:domain"),

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemGroupedEventsRow.kt

@@ -43,7 +43,7 @@ fun TimelineItemGroupedEventsRow(
     timelineRoomInfo: TimelineRoomInfo,
     renderReadReceipts: Boolean,
     isLastOutgoingMessage: Boolean,
-    highlightedItem: String?,
+    focusedEventId: EventId?,
     onClick: (TimelineItem.Event) -> Unit,
     onLongClick: (TimelineItem.Event) -> Unit,
     inReplyToClick: (EventId) -> Unit,
@@ -68,7 +68,7 @@ fun TimelineItemGroupedEventsRow(
         onExpandGroupClick = ::onExpandGroupClick,
         timelineItem = timelineItem,
         timelineRoomInfo = timelineRoomInfo,
-        highlightedItem = highlightedItem,
+        focusedEventId = focusedEventId,
         renderReadReceipts = renderReadReceipts,
         isLastOutgoingMessage = isLastOutgoingMessage,
         onClick = onClick,
@@ -92,7 +92,7 @@ private fun TimelineItemGroupedEventsRowContent(
     onExpandGroupClick: () -> Unit,
     timelineItem: TimelineItem.GroupedEvents,
     timelineRoomInfo: TimelineRoomInfo,
-    highlightedItem: String?,
+    focusedEventId: EventId?,
     renderReadReceipts: Boolean,
     isLastOutgoingMessage: Boolean,
     onClick: (TimelineItem.Event) -> Unit,
@@ -116,7 +116,7 @@ private fun TimelineItemGroupedEventsRowContent(
                 timelineItem.events.size
             ),
             isExpanded = isExpanded,
-            isHighlighted = !isExpanded && timelineItem.events.any { it.identifier() == highlightedItem },
+            isHighlighted = !isExpanded && timelineItem.events.any { it.isEvent(focusedEventId) },
             onClick = onExpandGroupClick,
         )
         if (isExpanded) {
@@ -127,7 +127,7 @@ private fun TimelineItemGroupedEventsRowContent(
                         timelineRoomInfo = timelineRoomInfo,
                         renderReadReceipts = renderReadReceipts,
                         isLastOutgoingMessage = isLastOutgoingMessage,
-                        highlightedItem = highlightedItem,
+                        focusedEventId = focusedEventId,
                         onClick = onClick,
                         onLongClick = onLongClick,
                         inReplyToClick = inReplyToClick,
@@ -160,12 +160,13 @@ private fun TimelineItemGroupedEventsRowContent(
 @PreviewsDayNight
 @Composable
 internal fun TimelineItemGroupedEventsRowContentExpandedPreview() = ElementPreview {
+    val events = aGroupedEvents(withReadReceipts = true)
     TimelineItemGroupedEventsRowContent(
         isExpanded = true,
         onExpandGroupClick = {},
-        timelineItem = aGroupedEvents(withReadReceipts = true),
+        timelineItem = events,
         timelineRoomInfo = aTimelineRoomInfo(),
-        highlightedItem = null,
+        focusedEventId = events.events.first().eventId,
         renderReadReceipts = true,
         isLastOutgoingMessage = false,
         onClick = {},
@@ -190,7 +191,7 @@ internal fun TimelineItemGroupedEventsRowContentCollapsePreview() = ElementPrevi
         onExpandGroupClick = {},
         timelineItem = aGroupedEvents(withReadReceipts = true),
         timelineRoomInfo = aTimelineRoomInfo(),
-        highlightedItem = null,
+        focusedEventId = null,
         renderReadReceipts = true,
         isLastOutgoingMessage = false,
         onClick = {},

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemRow.kt

@@ -16,13 +16,24 @@
 
 package io.element.android.features.messages.impl.timeline.components
 
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.padding
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.drawWithCache
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.graphics.Brush
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import io.element.android.compound.theme.ElementTheme
 import io.element.android.features.messages.impl.timeline.TimelineEvents
 import io.element.android.features.messages.impl.timeline.TimelineRoomInfo
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemLegacyCallInviteContent
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemStateContent
+import io.element.android.libraries.designsystem.text.toPx
+import io.element.android.libraries.designsystem.theme.highlightedMessageBackgroundColor
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.UserId
 
@@ -32,7 +43,7 @@ internal fun TimelineItemRow(
     timelineRoomInfo: TimelineRoomInfo,
     renderReadReceipts: Boolean,
     isLastOutgoingMessage: Boolean,
-    highlightedItem: String?,
+    focusedEventId: EventId?,
     onUserDataClick: (UserId) -> Unit,
     onLinkClicked: (String) -> Unit,
     onClick: (TimelineItem.Event) -> Unit,
@@ -47,69 +58,111 @@ internal fun TimelineItemRow(
     eventSink: (TimelineEvents.EventFromTimelineItem) -> Unit,
     modifier: Modifier = Modifier
 ) {
-    when (timelineItem) {
-        is TimelineItem.Virtual -> {
-            TimelineItemVirtualRow(
-                virtual = timelineItem,
-                modifier = modifier,
-            )
+    val backgroundModifier = if (timelineItem.isEvent(focusedEventId)) {
+        val focusedEventOffset = if ((timelineItem as? TimelineItem.Event)?.showSenderInformation == true) {
+            14.dp
+        } else {
+            2.dp
         }
-        is TimelineItem.Event -> {
-            if (timelineItem.content is TimelineItemStateContent || timelineItem.content is TimelineItemLegacyCallInviteContent) {
-                TimelineItemStateEventRow(
-                    event = timelineItem,
-                    renderReadReceipts = renderReadReceipts,
-                    isLastOutgoingMessage = isLastOutgoingMessage,
-                    isHighlighted = highlightedItem == timelineItem.identifier(),
-                    onClick = { onClick(timelineItem) },
-                    onReadReceiptsClick = onReadReceiptClick,
-                    onLongClick = { onLongClick(timelineItem) },
+        Modifier.focusedEvent(focusedEventOffset)
+    } else {
+        Modifier
+    }
+    Box(modifier = modifier.then(backgroundModifier)) {
+        when (timelineItem) {
+            is TimelineItem.Virtual -> {
+                TimelineItemVirtualRow(
+                    virtual = timelineItem,
+                    timelineRoomInfo = timelineRoomInfo,
                     eventSink = eventSink,
-                    modifier = modifier,
                 )
-            } else {
-                TimelineItemEventRow(
-                    event = timelineItem,
+            }
+            is TimelineItem.Event -> {
+                if (timelineItem.content is TimelineItemStateContent || timelineItem.content is TimelineItemLegacyCallInviteContent) {
+                    TimelineItemStateEventRow(
+                        event = timelineItem,
+                        renderReadReceipts = renderReadReceipts,
+                        isLastOutgoingMessage = isLastOutgoingMessage,
+                        isHighlighted = timelineItem.isEvent(focusedEventId),
+                        onClick = { onClick(timelineItem) },
+                        onReadReceiptsClick = onReadReceiptClick,
+                        onLongClick = { onLongClick(timelineItem) },
+                        eventSink = eventSink,
+                    )
+                } else {
+                    TimelineItemEventRow(
+                        event = timelineItem,
+                        timelineRoomInfo = timelineRoomInfo,
+                        renderReadReceipts = renderReadReceipts,
+                        isLastOutgoingMessage = isLastOutgoingMessage,
+                        isHighlighted = timelineItem.isEvent(focusedEventId),
+                        onClick = { onClick(timelineItem) },
+                        onLongClick = { onLongClick(timelineItem) },
+                        onUserDataClick = onUserDataClick,
+                        onLinkClicked = onLinkClicked,
+                        inReplyToClick = inReplyToClick,
+                        onReactionClick = onReactionClick,
+                        onReactionLongClick = onReactionLongClick,
+                        onMoreReactionsClick = onMoreReactionsClick,
+                        onReadReceiptClick = onReadReceiptClick,
+                        onTimestampClicked = onTimestampClicked,
+                        onSwipeToReply = { onSwipeToReply(timelineItem) },
+                        eventSink = eventSink,
+                    )
+                }
+            }
+            is TimelineItem.GroupedEvents -> {
+                TimelineItemGroupedEventsRow(
+                    timelineItem = timelineItem,
                     timelineRoomInfo = timelineRoomInfo,
                     renderReadReceipts = renderReadReceipts,
                     isLastOutgoingMessage = isLastOutgoingMessage,
-                    isHighlighted = highlightedItem == timelineItem.identifier(),
-                    onClick = { onClick(timelineItem) },
-                    onLongClick = { onLongClick(timelineItem) },
+                    focusedEventId = focusedEventId,
+                    onClick = onClick,
+                    onLongClick = onLongClick,
+                    inReplyToClick = inReplyToClick,
                     onUserDataClick = onUserDataClick,
                     onLinkClicked = onLinkClicked,
-                    inReplyToClick = inReplyToClick,
+                    onTimestampClicked = onTimestampClicked,
                     onReactionClick = onReactionClick,
                     onReactionLongClick = onReactionLongClick,
                     onMoreReactionsClick = onMoreReactionsClick,
                     onReadReceiptClick = onReadReceiptClick,
-                    onTimestampClicked = onTimestampClicked,
-                    onSwipeToReply = { onSwipeToReply(timelineItem) },
                     eventSink = eventSink,
-                    modifier = modifier,
                 )
             }
         }
-        is TimelineItem.GroupedEvents -> {
-            TimelineItemGroupedEventsRow(
-                timelineItem = timelineItem,
-                timelineRoomInfo = timelineRoomInfo,
-                renderReadReceipts = renderReadReceipts,
-                isLastOutgoingMessage = isLastOutgoingMessage,
-                highlightedItem = highlightedItem,
-                onClick = onClick,
-                onLongClick = onLongClick,
-                inReplyToClick = inReplyToClick,
-                onUserDataClick = onUserDataClick,
-                onLinkClicked = onLinkClicked,
-                onTimestampClicked = onTimestampClicked,
-                onReactionClick = onReactionClick,
-                onReactionLongClick = onReactionLongClick,
-                onMoreReactionsClick = onMoreReactionsClick,
-                onReadReceiptClick = onReadReceiptClick,
-                eventSink = eventSink,
-                modifier = modifier,
-            )
-        }
     }
 }
+
+@Suppress("ModifierComposable")
+@Composable
+private fun Modifier.focusedEvent(
+    focusedEventOffset: Dp
+): Modifier {
+    val highlightedLineColor = ElementTheme.colors.textActionAccent
+    val gradientColors = listOf(
+        ElementTheme.colors.highlightedMessageBackgroundColor,
+        ElementTheme.materialColors.background
+    )
+    val verticalOffset = focusedEventOffset.toPx()
+    val verticalRatio = 0.7f
+    return drawWithCache {
+        val brush = Brush.verticalGradient(
+            colors = gradientColors,
+            endY = size.height * verticalRatio,
+        )
+        onDrawBehind {
+            drawRect(
+                brush,
+                topLeft = Offset(0f, verticalOffset),
+                size = Size(size.width, size.height * verticalRatio)
+            )
+            drawLine(
+                highlightedLineColor,
+                start = Offset(0f, verticalOffset),
+                end = Offset(size.width, verticalOffset)
+            )
+        }
+    }.padding(top = 4.dp)
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemVirtualRow.kt

@@ -16,24 +16,51 @@
 
 package io.element.android.features.messages.impl.timeline.components
 
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.rememberUpdatedState
 import androidx.compose.ui.Modifier
+import io.element.android.features.messages.impl.timeline.TimelineEvents
+import io.element.android.features.messages.impl.timeline.TimelineRoomInfo
 import io.element.android.features.messages.impl.timeline.components.virtual.TimelineEncryptedHistoryBannerView
 import io.element.android.features.messages.impl.timeline.components.virtual.TimelineItemDaySeparatorView
 import io.element.android.features.messages.impl.timeline.components.virtual.TimelineItemReadMarkerView
+import io.element.android.features.messages.impl.timeline.components.virtual.TimelineItemRoomBeginningView
+import io.element.android.features.messages.impl.timeline.components.virtual.TimelineLoadingMoreIndicator
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemDaySeparatorModel
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemEncryptedHistoryBannerVirtualModel
+import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemLastForwardIndicatorModel
+import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemLoadingIndicatorModel
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemReadMarkerModel
+import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemRoomBeginningModel
 
 @Composable
 fun TimelineItemVirtualRow(
     virtual: TimelineItem.Virtual,
+    timelineRoomInfo: TimelineRoomInfo,
+    eventSink: (TimelineEvents.EventFromTimelineItem) -> Unit,
     modifier: Modifier = Modifier
 ) {
-    when (virtual.model) {
-        is TimelineItemDaySeparatorModel -> TimelineItemDaySeparatorView(virtual.model, modifier)
-        TimelineItemReadMarkerModel -> TimelineItemReadMarkerView()
-        is TimelineItemEncryptedHistoryBannerVirtualModel -> TimelineEncryptedHistoryBannerView(modifier)
+    Box(modifier = modifier) {
+        when (virtual.model) {
+            is TimelineItemDaySeparatorModel -> TimelineItemDaySeparatorView(virtual.model)
+            TimelineItemReadMarkerModel -> TimelineItemReadMarkerView()
+            is TimelineItemEncryptedHistoryBannerVirtualModel -> TimelineEncryptedHistoryBannerView()
+            TimelineItemRoomBeginningModel -> TimelineItemRoomBeginningView(roomName = timelineRoomInfo.name)
+            is TimelineItemLoadingIndicatorModel -> {
+                TimelineLoadingMoreIndicator(virtual.model.direction)
+                val latestEventSink by rememberUpdatedState(eventSink)
+                LaunchedEffect(virtual.model.timestamp) {
+                    latestEventSink(TimelineEvents.LoadMore(virtual.model.direction))
+                }
+            }
+            is TimelineItemLastForwardIndicatorModel -> {
+                Spacer(modifier = Modifier)
+            }
+        }
     }
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/virtual/TimelineLoadingMoreIndicator.kt

@@ -16,10 +16,12 @@
 
 package io.element.android.features.messages.impl.timeline.components.virtual
 
+import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.wrapContentHeight
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -27,24 +29,45 @@ import androidx.compose.ui.unit.dp
 import io.element.android.libraries.designsystem.preview.ElementPreview
 import io.element.android.libraries.designsystem.preview.PreviewsDayNight
 import io.element.android.libraries.designsystem.theme.components.CircularProgressIndicator
+import io.element.android.libraries.designsystem.theme.components.LinearProgressIndicator
+import io.element.android.libraries.matrix.api.timeline.Timeline
 
 @Composable
-internal fun TimelineLoadingMoreIndicator(modifier: Modifier = Modifier) {
+internal fun TimelineLoadingMoreIndicator(
+    direction: Timeline.PaginationDirection,
+    modifier: Modifier = Modifier
+) {
     Box(
-        modifier
-            .fillMaxWidth()
-            .wrapContentHeight()
-            .padding(8.dp),
+        modifier = modifier.fillMaxWidth(),
         contentAlignment = Alignment.Center,
     ) {
-        CircularProgressIndicator(
-            strokeWidth = 2.dp,
-        )
+        when (direction) {
+            Timeline.PaginationDirection.FORWARDS -> {
+                LinearProgressIndicator(
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(top = 2.dp)
+                        .height(1.dp)
+                )
+            }
+            Timeline.PaginationDirection.BACKWARDS -> {
+                CircularProgressIndicator(
+                    strokeWidth = 2.dp,
+                    modifier = Modifier.padding(vertical = 8.dp)
+                )
+            }
+        }
     }
 }
 
 @PreviewsDayNight
 @Composable
 internal fun TimelineLoadingMoreIndicatorPreview() = ElementPreview {
-    TimelineLoadingMoreIndicator()
+    Column(
+        modifier = Modifier.padding(vertical = 2.dp),
+        verticalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        TimelineLoadingMoreIndicator(Timeline.PaginationDirection.BACKWARDS)
+        TimelineLoadingMoreIndicator(Timeline.PaginationDirection.FORWARDS)
+    }
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/factories/TimelineItemsFactory.kt

@@ -19,6 +19,7 @@ package io.element.android.features.messages.impl.timeline.factories
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.State
 import androidx.compose.runtime.collectAsState
+import io.element.android.features.messages.impl.timeline.TimelineItemIndexer
 import io.element.android.features.messages.impl.timeline.diff.TimelineItemsCacheInvalidator
 import io.element.android.features.messages.impl.timeline.factories.event.TimelineItemEventFactory
 import io.element.android.features.messages.impl.timeline.factories.virtual.TimelineItemVirtualFactory
@@ -43,9 +44,9 @@ class TimelineItemsFactory @Inject constructor(
     private val eventItemFactory: TimelineItemEventFactory,
     private val virtualItemFactory: TimelineItemVirtualFactory,
     private val timelineItemGrouper: TimelineItemGrouper,
+    private val timelineItemIndexer: TimelineItemIndexer,
 ) {
     private val timelineItems = MutableStateFlow(persistentListOf<TimelineItem>())
-
     private val lock = Mutex()
     private val diffCache = MutableListDiffCache<TimelineItem>()
     private val diffCacheUpdater = DiffCacheUpdater<MatrixTimelineItem, TimelineItem>(
@@ -100,6 +101,7 @@ class TimelineItemsFactory @Inject constructor(
             }
         }
         val result = timelineItemGrouper.group(newTimelineItemStates).toPersistentList()
+        timelineItemIndexer.process(result)
         this.timelineItems.emit(result)
     }
 
@@ -108,13 +110,13 @@ class TimelineItemsFactory @Inject constructor(
         index: Int,
         roomMembers: List<RoomMember>,
     ): TimelineItem? {
-        val timelineItemState =
+        val timelineItem =
             when (val currentTimelineItem = timelineItems[index]) {
                 is MatrixTimelineItem.Event -> eventItemFactory.create(currentTimelineItem, index, timelineItems, roomMembers)
                 is MatrixTimelineItem.Virtual -> virtualItemFactory.create(currentTimelineItem)
                 MatrixTimelineItem.Other -> null
             }
-        diffCache[index] = timelineItemState
-        return timelineItemState
+        diffCache[index] = timelineItem
+        return timelineItem
     }
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/factories/virtual/TimelineItemVirtualFactory.kt

@@ -18,7 +18,10 @@ package io.element.android.features.messages.impl.timeline.factories.virtual
 
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemEncryptedHistoryBannerVirtualModel
+import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemLastForwardIndicatorModel
+import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemLoadingIndicatorModel
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemReadMarkerModel
+import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemRoomBeginningModel
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemVirtualModel
 import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
 import io.element.android.libraries.matrix.api.timeline.item.virtual.VirtualTimelineItem
@@ -41,6 +44,12 @@ class TimelineItemVirtualFactory @Inject constructor(
             is VirtualTimelineItem.DayDivider -> daySeparatorFactory.create(inner)
             is VirtualTimelineItem.ReadMarker -> TimelineItemReadMarkerModel
             is VirtualTimelineItem.EncryptedHistoryBanner -> TimelineItemEncryptedHistoryBannerVirtualModel
+            is VirtualTimelineItem.RoomBeginning -> TimelineItemRoomBeginningModel
+            is VirtualTimelineItem.LoadingIndicator -> TimelineItemLoadingIndicatorModel(
+                direction = inner.direction,
+                timestamp = inner.timestamp
+            )
+            is VirtualTimelineItem.LastForwardIndicator -> TimelineItemLastForwardIndicatorModel
         }
     }
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/focus/FocusRequestStateProvider.kt

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline.focus
+
+import androidx.compose.ui.tooling.preview.PreviewParameterProvider
+import io.element.android.features.messages.impl.timeline.FocusRequestState
+import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.room.errors.FocusEventException
+
+open class FocusRequestStateProvider : PreviewParameterProvider<FocusRequestState> {
+    override val values: Sequence<FocusRequestState>
+        get() = sequenceOf(
+            FocusRequestState.Fetching,
+            FocusRequestState.Failure(
+                FocusEventException.EventNotFound(
+                    eventId = EventId("\$anEventId"),
+                )
+            ),
+            FocusRequestState.Failure(
+                FocusEventException.InvalidEventId(
+                    eventId = "invalid",
+                    err = "An error"
+                )
+            ),
+            FocusRequestState.Failure(
+                FocusEventException.Other(
+                    msg = "An error"
+                )
+            ),
+        )
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/focus/FocusRequestStateView.kt

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline.focus
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.PreviewParameter
+import io.element.android.features.messages.impl.timeline.FocusRequestState
+import io.element.android.libraries.designsystem.components.ProgressDialog
+import io.element.android.libraries.designsystem.components.dialogs.ErrorDialog
+import io.element.android.libraries.designsystem.preview.ElementPreview
+import io.element.android.libraries.designsystem.preview.PreviewsDayNight
+import io.element.android.libraries.matrix.api.room.errors.FocusEventException
+import io.element.android.libraries.ui.strings.CommonStrings
+
+@Composable
+fun FocusRequestStateView(
+    focusRequestState: FocusRequestState,
+    onClearFocusRequestState: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    when (focusRequestState) {
+        is FocusRequestState.Failure -> {
+            val errorMessage = when (focusRequestState.throwable) {
+                is FocusEventException.EventNotFound,
+                is FocusEventException.InvalidEventId -> stringResource(id = CommonStrings.error_message_not_found)
+                is FocusEventException.Other -> stringResource(id = CommonStrings.error_unknown)
+                else -> stringResource(id = CommonStrings.error_unknown)
+            }
+            ErrorDialog(
+                content = errorMessage,
+                onDismiss = onClearFocusRequestState,
+                modifier = modifier,
+            )
+        }
+        FocusRequestState.Fetching -> {
+            ProgressDialog(modifier = modifier, onDismissRequest = onClearFocusRequestState)
+        }
+        else -> Unit
+    }
+}
+
+@PreviewsDayNight
+@Composable
+internal fun FocusRequestStateViewPreview(
+    @PreviewParameter(FocusRequestStateProvider::class) state: FocusRequestState,
+) = ElementPreview {
+    FocusRequestStateView(
+        focusRequestState = state,
+        onClearFocusRequestState = {},
+    )
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/InReplyToDetails.kt

@@ -16,6 +16,7 @@
 
 package io.element.android.features.messages.impl.timeline.model
 
+import androidx.compose.runtime.Immutable
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.permalink.PermalinkParser
@@ -27,18 +28,30 @@ import io.element.android.libraries.matrix.api.timeline.item.event.StickerConten
 import io.element.android.libraries.matrix.api.timeline.item.event.TextMessageType
 import io.element.android.libraries.matrix.ui.messages.toPlainText
 
-data class InReplyToDetails(
-    val eventId: EventId,
-    val senderId: UserId,
-    val senderProfile: ProfileTimelineDetails,
-    val eventContent: EventContent?,
-    val textContent: String?,
-)
+@Immutable
+sealed interface InReplyToDetails {
+    data class Ready(
+        val eventId: EventId,
+        val senderId: UserId,
+        val senderProfile: ProfileTimelineDetails,
+        val eventContent: EventContent?,
+        val textContent: String?,
+    ) : InReplyToDetails
+
+    data class Loading(val eventId: EventId) : InReplyToDetails
+    data class Error(val eventId: EventId, val message: String) : InReplyToDetails
+}
+
+fun InReplyToDetails.eventId() = when (this) {
+    is InReplyToDetails.Ready -> eventId
+    is InReplyToDetails.Loading -> eventId
+    is InReplyToDetails.Error -> eventId
+}
 
 fun InReplyTo.map(
     permalinkParser: PermalinkParser,
 ) = when (this) {
-    is InReplyTo.Ready -> InReplyToDetails(
+    is InReplyTo.Ready -> InReplyToDetails.Ready(
         eventId = eventId,
         senderId = senderId,
         senderProfile = senderProfile,
@@ -55,5 +68,7 @@ fun InReplyTo.map(
             else -> null
         }
     )
-    else -> null
+    is InReplyTo.Error -> InReplyToDetails.Error(eventId, message)
+    is InReplyTo.NotLoaded -> InReplyToDetails.Loading(eventId)
+    is InReplyTo.Pending -> InReplyToDetails.Loading(eventId)
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/InReplyToMetadata.kt

@@ -66,7 +66,7 @@ internal sealed interface InReplyToMetadata {
  * Metadata can be either a thumbnail with a text OR just a text.
  */
 @Composable
-internal fun InReplyToDetails.metadata(): InReplyToMetadata? = when (eventContent) {
+internal fun InReplyToDetails.Ready.metadata(): InReplyToMetadata? = when (eventContent) {
     is MessageContent -> when (val type = eventContent.type) {
         is ImageMessageType -> InReplyToMetadata.Thumbnail(
             AttachmentThumbnailInfo(

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/TimelineItem.kt

@@ -40,6 +40,14 @@ sealed interface TimelineItem {
         is GroupedEvents -> id
     }
 
+    fun isEvent(eventId: EventId?): Boolean {
+        if (eventId == null) return false
+        return when (this) {
+            is Event -> this.eventId == eventId
+            else -> false
+        }
+    }
+
     fun contentType(): String = when (this) {
         is Event -> content.type
         is Virtual -> model.type

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/virtual/TimelineItemLastForwardIndicatorModel.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline.model.virtual
+
+data object TimelineItemLastForwardIndicatorModel : TimelineItemVirtualModel {
+    override val type: String = "TimelineItemLastForwardIndicatorModel"
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/virtual/TimelineItemLoadingIndicatorModel.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline.model.virtual
+
+import io.element.android.libraries.matrix.api.timeline.Timeline
+
+data class TimelineItemLoadingIndicatorModel(
+    val direction: Timeline.PaginationDirection,
+    val timestamp: Long,
+) : TimelineItemVirtualModel {
+    override val type: String = "TimelineItemLoadingIndicatorModel"
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/virtual/TimelineItemRoomBeginningModel.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline.model.virtual
+
+data object TimelineItemRoomBeginningModel : TimelineItemVirtualModel {
+    override val type: String = "TimelineItemRoomBeginningModel"
+}

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/MessagesPresenterTest.kt

@@ -31,6 +31,8 @@ import io.element.android.features.messages.impl.messagecomposer.MessageComposer
 import io.element.android.features.messages.impl.messagecomposer.MessageComposerPresenter
 import io.element.android.features.messages.impl.messagesummary.FakeMessageSummaryFormatter
 import io.element.android.features.messages.impl.textcomposer.TestRichTextEditorStateFactory
+import io.element.android.features.messages.impl.timeline.TimelineController
+import io.element.android.features.messages.impl.timeline.TimelineItemIndexer
 import io.element.android.features.messages.impl.timeline.TimelinePresenter
 import io.element.android.features.messages.impl.timeline.components.customreaction.CustomReactionPresenter
 import io.element.android.features.messages.impl.timeline.components.customreaction.FakeEmojibaseProvider
@@ -63,6 +65,7 @@ import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
 import io.element.android.libraries.featureflag.test.InMemoryAppPreferencesStore
 import io.element.android.libraries.featureflag.test.InMemorySessionPreferencesStore
+import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.media.MediaSource
 import io.element.android.libraries.matrix.api.room.MatrixRoom
 import io.element.android.libraries.matrix.api.room.MatrixRoomMembersState
@@ -81,6 +84,7 @@ import io.element.android.libraries.matrix.test.permalink.FakePermalinkParser
 import io.element.android.libraries.matrix.test.room.FakeMatrixRoom
 import io.element.android.libraries.matrix.test.room.aRoomInfo
 import io.element.android.libraries.matrix.test.room.aRoomMember
+import io.element.android.libraries.matrix.test.timeline.FakeTimeline
 import io.element.android.libraries.mediapickers.test.FakePickerProvider
 import io.element.android.libraries.mediaplayer.test.FakeMediaPlayer
 import io.element.android.libraries.mediaupload.api.MediaSender
@@ -95,6 +99,9 @@ import io.element.android.services.analytics.test.FakeAnalyticsService
 import io.element.android.tests.testutils.WarmUpRule
 import io.element.android.tests.testutils.consumeItemsUntilPredicate
 import io.element.android.tests.testutils.consumeItemsUntilTimeout
+import io.element.android.tests.testutils.lambda.assert
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
 import io.element.android.tests.testutils.testCoroutineDispatchers
 import io.mockk.mockk
 import kotlinx.collections.immutable.persistentListOf
@@ -167,7 +174,13 @@ class MessagesPresenterTest {
     @Test
     fun `present - handle toggling a reaction`() = runTest {
         val coroutineDispatchers = testCoroutineDispatchers(useUnconfinedTestDispatcher = true)
-        val room = FakeMatrixRoom()
+        val toggleReactionSuccess = lambdaRecorder { _: String, _: EventId -> Result.success(Unit) }
+        val toggleReactionFailure = lambdaRecorder { _: String, _: EventId -> Result.failure<Unit>(IllegalStateException("Failed to send reaction")) }
+
+        val timeline = FakeTimeline().apply {
+            this.toggleReactionLambda = toggleReactionSuccess
+        }
+        val room = FakeMatrixRoom(liveTimeline = timeline)
         val presenter = createMessagesPresenter(matrixRoom = room, coroutineDispatchers = coroutineDispatchers)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
@@ -175,29 +188,42 @@ class MessagesPresenterTest {
             skipItems(1)
             val initialState = awaitItem()
             initialState.eventSink.invoke(MessagesEvents.ToggleReaction("👍", AN_EVENT_ID))
-            assertThat(room.myReactions.count()).isEqualTo(1)
             // No crashes when sending a reaction failed
-            room.givenToggleReactionResult(Result.failure(IllegalStateException("Failed to send reaction")))
+            timeline.apply { toggleReactionLambda = toggleReactionFailure }
             initialState.eventSink.invoke(MessagesEvents.ToggleReaction("👍", AN_EVENT_ID))
-            assertThat(room.myReactions.count()).isEqualTo(1)
             assertThat(awaitItem().actionListState.target).isEqualTo(ActionListState.Target.None)
+
+            assert(toggleReactionSuccess)
+                .isCalledOnce()
+                .with(value("👍"), value(AN_EVENT_ID))
+            assert(toggleReactionFailure)
+                .isCalledOnce()
+                .with(value("👍"), value(AN_EVENT_ID))
         }
     }
 
     @Test
     fun `present - handle toggling a reaction twice`() = runTest {
         val coroutineDispatchers = testCoroutineDispatchers(useUnconfinedTestDispatcher = true)
-        val room = FakeMatrixRoom()
+        val toggleReactionSuccess = lambdaRecorder { _: String, _: EventId -> Result.success(Unit) }
+
+        val timeline = FakeTimeline().apply {
+            this.toggleReactionLambda = toggleReactionSuccess
+        }
+        val room = FakeMatrixRoom(liveTimeline = timeline)
         val presenter = createMessagesPresenter(matrixRoom = room, coroutineDispatchers = coroutineDispatchers)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
             val initialState = awaitFirstItem()
             initialState.eventSink.invoke(MessagesEvents.ToggleReaction("👍", AN_EVENT_ID))
-            assertThat(room.myReactions.count()).isEqualTo(1)
-
             initialState.eventSink.invoke(MessagesEvents.ToggleReaction("👍", AN_EVENT_ID))
-            assertThat(room.myReactions.count()).isEqualTo(0)
+            assert(toggleReactionSuccess)
+                .isCalledExactly(2)
+                .withSequence(
+                    listOf(value("👍"), value(AN_EVENT_ID)),
+                    listOf(value("👍"), value(AN_EVENT_ID)),
+                )
         }
     }
 
@@ -272,7 +298,7 @@ class MessagesPresenterTest {
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            skipItems(3)
+            skipItems(2)
             val initialState = awaitItem()
             initialState.eventSink.invoke(MessagesEvents.HandleAction(TimelineItemAction.Reply, aMessageEvent(eventId = null)))
             assertThat(awaitItem().actionListState.target).isEqualTo(ActionListState.Target.None)
@@ -428,7 +454,6 @@ class MessagesPresenterTest {
             initialState.eventSink.invoke(MessagesEvents.HandleAction(TimelineItemAction.Redact, aMessageEvent()))
             assertThat(matrixRoom.redactEventEventIdParam).isEqualTo(AN_EVENT_ID)
             assertThat(awaitItem().actionListState.target).isEqualTo(ActionListState.Target.None)
-            skipItems(1) // back paginating
         }
     }
 
@@ -748,6 +773,7 @@ class MessagesPresenterTest {
             currentSessionIdHolder = CurrentSessionIdHolder(FakeMatrixClient(A_SESSION_ID)),
             permalinkParser = FakePermalinkParser(),
             permalinkBuilder = FakePermalinkBuilder(),
+            timelineController = TimelineController(matrixRoom),
         )
         val voiceMessageComposerPresenter = VoiceMessageComposerPresenter(
             this,
@@ -768,6 +794,8 @@ class MessagesPresenterTest {
             endPollAction = endPollAction,
             sendPollResponseAction = FakeSendPollResponseAction(),
             sessionPreferencesStore = sessionPreferencesStore,
+            timelineItemIndexer = TimelineItemIndexer(),
+            timelineController = TimelineController(matrixRoom),
         )
         val timelinePresenterFactory = object : TimelinePresenter.Factory {
             override fun create(navigator: MessagesNavigator): TimelinePresenter {
@@ -804,6 +832,7 @@ class MessagesPresenterTest {
             buildMeta = aBuildMeta(),
             dispatchers = coroutineDispatchers,
             htmlConverterProvider = FakeHtmlConverterProvider(),
+            timelineController = TimelineController(matrixRoom),
         )
     }
 }

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/fixtures/TimelineItemsFactoryFixtures.kt

@@ -16,6 +16,7 @@
 
 package io.element.android.features.messages.impl.fixtures
 
+import io.element.android.features.messages.impl.timeline.TimelineItemIndexer
 import io.element.android.features.messages.impl.timeline.factories.TimelineItemsFactory
 import io.element.android.features.messages.impl.timeline.factories.event.TimelineItemContentFactory
 import io.element.android.features.messages.impl.timeline.factories.event.TimelineItemContentFailedToParseMessageFactory
@@ -46,7 +47,9 @@ import io.element.android.libraries.mediaviewer.api.util.FileExtensionExtractorW
 import io.element.android.tests.testutils.testCoroutineDispatchers
 import kotlinx.coroutines.test.TestScope
 
-internal fun TestScope.aTimelineItemsFactory(): TimelineItemsFactory {
+internal fun TestScope.aTimelineItemsFactory(
+    timelineItemIndexer: TimelineItemIndexer = TimelineItemIndexer()
+): TimelineItemsFactory {
     val timelineEventFormatter = aTimelineEventFormatter()
     val matrixClient = FakeMatrixClient()
     return TimelineItemsFactory(
@@ -83,6 +86,7 @@ internal fun TestScope.aTimelineItemsFactory(): TimelineItemsFactory {
             ),
         ),
         timelineItemGrouper = TimelineItemGrouper(),
+        timelineItemIndexer = timelineItemIndexer,
     )
 }
 

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/forward/ForwardMessagesPresenterTests.kt

@@ -21,14 +21,20 @@ import app.cash.molecule.moleculeFlow
 import app.cash.turbine.test
 import com.google.common.truth.Truth.assertThat
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.RoomId
 import io.element.android.libraries.matrix.test.AN_EVENT_ID
 import io.element.android.libraries.matrix.test.room.FakeMatrixRoom
 import io.element.android.libraries.matrix.test.room.aRoomSummaryDetails
+import io.element.android.libraries.matrix.test.timeline.FakeTimeline
+import io.element.android.libraries.matrix.test.timeline.LiveTimelineProvider
 import io.element.android.tests.testutils.WarmUpRule
+import io.element.android.tests.testutils.lambda.assert
+import io.element.android.tests.testutils.lambda.lambdaRecorder
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.test.runTest
 import org.junit.Rule
 import org.junit.Test
+import java.lang.IllegalStateException
 
 class ForwardMessagesPresenterTests {
     @get:Rule
@@ -36,7 +42,7 @@ class ForwardMessagesPresenterTests {
 
     @Test
     fun `present - initial state`() = runTest {
-        val presenter = aPresenter()
+        val presenter = aForwardMessagesPresenter()
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
@@ -49,7 +55,14 @@ class ForwardMessagesPresenterTests {
 
     @Test
     fun `present - forward successful`() = runTest {
-        val presenter = aPresenter()
+        val forwardEventLambda = lambdaRecorder { _: EventId, _: List<RoomId> ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline().apply {
+            this.forwardEventLambda = forwardEventLambda
+        }
+        val room = FakeMatrixRoom(liveTimeline = timeline)
+        val presenter = aForwardMessagesPresenter(fakeMatrixRoom = room)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
@@ -61,18 +74,23 @@ class ForwardMessagesPresenterTests {
             val successfulForwardState = awaitItem()
             assertThat(successfulForwardState.isForwarding).isFalse()
             assertThat(successfulForwardState.forwardingSucceeded).isNotNull()
+            assert(forwardEventLambda).isCalledOnce()
         }
     }
 
     @Test
     fun `present - select a room and forward failed, then clear`() = runTest {
-        val room = FakeMatrixRoom()
-        val presenter = aPresenter(fakeMatrixRoom = room)
+        val forwardEventLambda = lambdaRecorder { _: EventId, _: List<RoomId> ->
+            Result.failure<Unit>(IllegalStateException("error"))
+        }
+        val timeline = FakeTimeline().apply {
+            this.forwardEventLambda = forwardEventLambda
+        }
+        val room = FakeMatrixRoom(liveTimeline = timeline)
+        val presenter = aForwardMessagesPresenter(fakeMatrixRoom = room)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            // Test failed forwarding
-            room.givenForwardEventResult(Result.failure(Throwable("error")))
             skipItems(1)
             val summary = aRoomSummaryDetails()
             presenter.onRoomSelected(listOf(summary.roomId))
@@ -82,16 +100,17 @@ class ForwardMessagesPresenterTests {
             // Then clear error
             failedForwardState.eventSink(ForwardMessagesEvents.ClearError)
             assertThat(awaitItem().error).isNull()
+            assert(forwardEventLambda).isCalledOnce()
         }
     }
 
-    private fun CoroutineScope.aPresenter(
+    private fun CoroutineScope.aForwardMessagesPresenter(
         eventId: EventId = AN_EVENT_ID,
         fakeMatrixRoom: FakeMatrixRoom = FakeMatrixRoom(),
         coroutineScope: CoroutineScope = this,
     ) = ForwardMessagesPresenter(
         eventId = eventId.value,
-        room = fakeMatrixRoom,
+        timelineProvider = LiveTimelineProvider(fakeMatrixRoom),
         matrixCoroutineScope = coroutineScope,
     )
 }

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/textcomposer/MessageComposerPresenterTest.kt

@@ -32,6 +32,7 @@ import io.element.android.features.messages.impl.messagecomposer.MessageComposer
 import io.element.android.features.messages.impl.messagecomposer.MessageComposerEvents
 import io.element.android.features.messages.impl.messagecomposer.MessageComposerPresenter
 import io.element.android.features.messages.impl.messagecomposer.MessageComposerState
+import io.element.android.features.messages.impl.timeline.TimelineController
 import io.element.android.features.preferences.api.store.SessionPreferencesStore
 import io.element.android.libraries.core.mimetype.MimeTypes
 import io.element.android.libraries.designsystem.utils.snackbar.SnackbarDispatcher
@@ -65,6 +66,7 @@ import io.element.android.libraries.matrix.test.permalink.FakePermalinkBuilder
 import io.element.android.libraries.matrix.test.permalink.FakePermalinkParser
 import io.element.android.libraries.matrix.test.room.FakeMatrixRoom
 import io.element.android.libraries.matrix.test.room.aRoomMember
+import io.element.android.libraries.matrix.test.timeline.FakeTimeline
 import io.element.android.libraries.mediapickers.api.PickerProvider
 import io.element.android.libraries.mediapickers.test.FakePickerProvider
 import io.element.android.libraries.mediaupload.api.MediaPreProcessor
@@ -81,6 +83,10 @@ import io.element.android.libraries.textcomposer.model.Suggestion
 import io.element.android.libraries.textcomposer.model.SuggestionType
 import io.element.android.services.analytics.test.FakeAnalyticsService
 import io.element.android.tests.testutils.WarmUpRule
+import io.element.android.tests.testutils.lambda.any
+import io.element.android.tests.testutils.lambda.assert
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
 import io.element.android.tests.testutils.waitForPredicate
 import io.mockk.mockk
 import kotlinx.collections.immutable.persistentListOf
@@ -259,7 +265,13 @@ class MessageComposerPresenterTest {
 
     @Test
     fun `present - edit sent message`() = runTest {
-        val fakeMatrixRoom = FakeMatrixRoom()
+        val editMessageLambda = lambdaRecorder { _: EventId?, _: TransactionId?, _: String, _: String?, _: List<Mention> ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline().apply {
+            this.editMessageLambda = editMessageLambda
+        }
+        val fakeMatrixRoom = FakeMatrixRoom(liveTimeline = timeline)
         val presenter = createPresenter(
             this,
             fakeMatrixRoom,
@@ -283,7 +295,13 @@ class MessageComposerPresenterTest {
             skipItems(1)
             val messageSentState = awaitItem()
             assertThat(messageSentState.richTextEditorState.messageHtml).isEqualTo("")
-            assertThat(fakeMatrixRoom.editMessageCalls.first()).isEqualTo(ANOTHER_MESSAGE to ANOTHER_MESSAGE)
+
+            advanceUntilIdle()
+
+            assert(editMessageLambda)
+                .isCalledOnce()
+                .with(any(), any(), value(ANOTHER_MESSAGE), value(ANOTHER_MESSAGE), any())
+
             assertThat(analyticsService.capturedEvents).containsExactly(
                 Composer(
                     inThread = false,
@@ -297,7 +315,13 @@ class MessageComposerPresenterTest {
 
     @Test
     fun `present - edit not sent message`() = runTest {
-        val fakeMatrixRoom = FakeMatrixRoom()
+        val editMessageLambda = lambdaRecorder { _: EventId?, _: TransactionId?, _: String, _: String?, _: List<Mention> ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline().apply {
+            this.editMessageLambda = editMessageLambda
+        }
+        val fakeMatrixRoom = FakeMatrixRoom(liveTimeline = timeline)
         val presenter = createPresenter(
             this,
             fakeMatrixRoom,
@@ -321,7 +345,13 @@ class MessageComposerPresenterTest {
             skipItems(1)
             val messageSentState = awaitItem()
             assertThat(messageSentState.richTextEditorState.messageHtml).isEqualTo("")
-            assertThat(fakeMatrixRoom.editMessageCalls.first()).isEqualTo(ANOTHER_MESSAGE to ANOTHER_MESSAGE)
+
+            advanceUntilIdle()
+
+            assert(editMessageLambda)
+                .isCalledOnce()
+                .with(any(), any(), value(ANOTHER_MESSAGE), value(ANOTHER_MESSAGE), any())
+
             assertThat(analyticsService.capturedEvents).containsExactly(
                 Composer(
                     inThread = false,
@@ -335,7 +365,13 @@ class MessageComposerPresenterTest {
 
     @Test
     fun `present - reply message`() = runTest {
-        val fakeMatrixRoom = FakeMatrixRoom()
+        val replyMessageLambda = lambdaRecorder { _: EventId, _: String, _: String?, _: List<Mention> ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline().apply {
+            this.replyMessageLambda = replyMessageLambda
+        }
+        val fakeMatrixRoom = FakeMatrixRoom(liveTimeline = timeline)
         val presenter = createPresenter(
             this,
             fakeMatrixRoom,
@@ -355,7 +391,13 @@ class MessageComposerPresenterTest {
             state.eventSink.invoke(MessageComposerEvents.SendMessage(A_REPLY.toMessage()))
             val messageSentState = awaitItem()
             assertThat(messageSentState.richTextEditorState.messageHtml).isEqualTo("")
-            assertThat(fakeMatrixRoom.replyMessageParameter).isEqualTo(A_REPLY to A_REPLY)
+
+            advanceUntilIdle()
+
+            assert(replyMessageLambda)
+                .isCalledOnce()
+                .with(any(), value(A_REPLY), value(A_REPLY), any())
+
             assertThat(analyticsService.capturedEvents).containsExactly(
                 Composer(
                     inThread = false,
@@ -831,7 +873,17 @@ class MessageComposerPresenterTest {
     @OptIn(ExperimentalCoroutinesApi::class)
     @Test
     fun `present - send messages with intentional mentions`() = runTest {
-        val room = FakeMatrixRoom()
+        val replyMessageLambda = lambdaRecorder { _: EventId, _: String, _: String?, _: List<Mention> ->
+            Result.success(Unit)
+        }
+        val editMessageLambda = lambdaRecorder { _: EventId?, _: TransactionId?, _: String, _: String?, _: List<Mention> ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline().apply {
+            this.replyMessageLambda = replyMessageLambda
+            this.editMessageLambda = editMessageLambda
+        }
+        val room = FakeMatrixRoom(liveTimeline = timeline)
         val presenter = createPresenter(room = room, coroutineScope = this)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
@@ -866,7 +918,9 @@ class MessageComposerPresenterTest {
             initialState.eventSink(MessageComposerEvents.SendMessage(A_MESSAGE.toMessage()))
             advanceUntilIdle()
 
-            assertThat(room.sendMessageMentions).isEqualTo(listOf(Mention.User(A_USER_ID_2)))
+            assert(replyMessageLambda)
+                .isCalledOnce()
+                .with(any(), any(), any(), value(listOf(Mention.User(A_USER_ID_2))))
 
             // Check intentional mentions on edit message
             skipItems(1)
@@ -882,7 +936,9 @@ class MessageComposerPresenterTest {
             initialState.eventSink(MessageComposerEvents.SendMessage(A_MESSAGE.toMessage()))
             advanceUntilIdle()
 
-            assertThat(room.sendMessageMentions).isEqualTo(listOf(Mention.User(A_USER_ID_3)))
+            assert(editMessageLambda)
+                .isCalledOnce()
+                .with(any(), any(), any(), any(), value(listOf(Mention.User(A_USER_ID_3))))
 
             skipItems(1)
         }
@@ -968,6 +1024,7 @@ class MessageComposerPresenterTest {
         permissionsPresenterFactory = FakePermissionsPresenterFactory(permissionPresenter),
         permalinkParser = FakePermalinkParser(),
         permalinkBuilder = permalinkBuilder,
+        timelineController = TimelineController(room),
     )
 
     private suspend fun <T> ReceiveTurbine<T>.awaitFirstItem(): T {

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/TimelineControllerTest.kt

@@ -0,0 +1,217 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline
+
+import app.cash.turbine.test
+import com.google.common.truth.Truth.assertThat
+import io.element.android.libraries.matrix.api.room.Mention
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.Timeline
+import io.element.android.libraries.matrix.test.AN_EVENT_ID
+import io.element.android.libraries.matrix.test.A_UNIQUE_ID
+import io.element.android.libraries.matrix.test.room.FakeMatrixRoom
+import io.element.android.libraries.matrix.test.timeline.FakeTimeline
+import io.element.android.libraries.matrix.test.timeline.anEventTimelineItem
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.test.runTest
+import org.junit.Test
+
+class TimelineControllerTest {
+    @Test
+    fun `test switching between live and detached timeline`() = runTest {
+        val liveTimeline = FakeTimeline(name = "live")
+        val detachedTimeline = FakeTimeline(name = "detached")
+        val matrixRoom = FakeMatrixRoom(
+            liveTimeline = liveTimeline
+        )
+        matrixRoom.givenTimelineFocusedOnEventResult(Result.success(detachedTimeline))
+        val sut = TimelineController(matrixRoom)
+
+        sut.activeTimelineFlow().test {
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(liveTimeline)
+            }
+            assertThat(sut.isLive().first()).isTrue()
+            sut.focusOnEvent(AN_EVENT_ID)
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(detachedTimeline)
+            }
+            assertThat(sut.isLive().first()).isFalse()
+            assertThat(detachedTimeline.closeCounter).isEqualTo(0)
+            sut.focusOnLive()
+            assertThat(sut.isLive().first()).isTrue()
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(liveTimeline)
+            }
+            assertThat(detachedTimeline.closeCounter).isEqualTo(1)
+        }
+    }
+
+    @Test
+    fun `test switching between detached 1 and detached 2 should close detached 1`() = runTest {
+        val liveTimeline = FakeTimeline(name = "live")
+        val detachedTimeline1 = FakeTimeline(name = "detached 1")
+        val detachedTimeline2 = FakeTimeline(name = "detached 2")
+        val matrixRoom = FakeMatrixRoom(
+            liveTimeline = liveTimeline
+        )
+        val sut = TimelineController(matrixRoom)
+
+        sut.activeTimelineFlow().test {
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(liveTimeline)
+            }
+            matrixRoom.givenTimelineFocusedOnEventResult(Result.success(detachedTimeline1))
+            sut.focusOnEvent(AN_EVENT_ID)
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(detachedTimeline1)
+            }
+            assertThat(detachedTimeline1.closeCounter).isEqualTo(0)
+            assertThat(detachedTimeline2.closeCounter).isEqualTo(0)
+            // Focus on another event should close the previous detached timeline
+            matrixRoom.givenTimelineFocusedOnEventResult(Result.success(detachedTimeline2))
+            sut.focusOnEvent(AN_EVENT_ID)
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(detachedTimeline2)
+            }
+            assertThat(detachedTimeline1.closeCounter).isEqualTo(1)
+            assertThat(detachedTimeline2.closeCounter).isEqualTo(0)
+        }
+    }
+
+    @Test
+    fun `test switching to live when already in live should have no effect`() = runTest {
+        val liveTimeline = FakeTimeline(name = "live")
+        val matrixRoom = FakeMatrixRoom(
+            liveTimeline = liveTimeline
+        )
+        val sut = TimelineController(matrixRoom)
+        sut.activeTimelineFlow().test {
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(liveTimeline)
+            }
+            assertThat(sut.isLive().first()).isTrue()
+            sut.focusOnLive()
+            assertThat(sut.isLive().first()).isTrue()
+        }
+    }
+
+    @Test
+    fun `test closing the TimelineController should close the detached timeline`() = runTest {
+        val liveTimeline = FakeTimeline(name = "live")
+        val detachedTimeline = FakeTimeline(name = "detached")
+        val matrixRoom = FakeMatrixRoom(
+            liveTimeline = liveTimeline
+        )
+        matrixRoom.givenTimelineFocusedOnEventResult(Result.success(detachedTimeline))
+        val sut = TimelineController(matrixRoom)
+
+        sut.activeTimelineFlow().test {
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(liveTimeline)
+            }
+            sut.focusOnEvent(AN_EVENT_ID)
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(detachedTimeline)
+            }
+            assertThat(detachedTimeline.closeCounter).isEqualTo(0)
+            sut.close()
+            assertThat(detachedTimeline.closeCounter).isEqualTo(1)
+        }
+    }
+
+    @Test
+    fun `test getting timeline item`() = runTest {
+        val liveTimeline = FakeTimeline(
+            name = "live",
+            timelineItems = flowOf(
+                listOf(
+                    MatrixTimelineItem.Event(A_UNIQUE_ID, anEventTimelineItem())
+                )
+            )
+        )
+        val matrixRoom = FakeMatrixRoom(
+            liveTimeline = liveTimeline
+        )
+        val sut = TimelineController(matrixRoom)
+        assertThat(sut.timelineItems().first()).hasSize(1)
+    }
+
+    @Test
+    fun `test invokeOnCurrentTimeline use the detached timeline and not the live timeline`() = runTest {
+        val lambdaForDetached = lambdaRecorder { _: String, _: String?, _: List<Mention> ->
+            Result.success(Unit)
+        }
+        val lambdaForLive = lambdaRecorder(ensureNeverCalled = true) { _: String, _: String?, _: List<Mention> ->
+            Result.success(Unit)
+        }
+        val liveTimeline = FakeTimeline(name = "live").apply {
+            sendMessageLambda = lambdaForLive
+        }
+        val detachedTimeline = FakeTimeline(name = "detached").apply {
+            sendMessageLambda = lambdaForDetached
+        }
+        val matrixRoom = FakeMatrixRoom(
+            liveTimeline = liveTimeline
+        )
+        matrixRoom.givenTimelineFocusedOnEventResult(Result.success(detachedTimeline))
+        val sut = TimelineController(matrixRoom)
+        sut.focusOnEvent(AN_EVENT_ID)
+        sut.activeTimelineFlow().test {
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(detachedTimeline)
+            }
+            sut.invokeOnCurrentTimeline {
+                sendMessage("body", "htmlBody", emptyList())
+            }
+            lambdaForDetached.assertions().isCalledOnce()
+        }
+    }
+
+    @Test
+    fun `test last forward pagination on a detached timeline should switch to live timeline`() = runTest {
+        val liveTimeline = FakeTimeline(name = "live")
+        val detachedTimeline = FakeTimeline(name = "detached")
+        val matrixRoom = FakeMatrixRoom(
+            liveTimeline = liveTimeline
+        )
+        matrixRoom.givenTimelineFocusedOnEventResult(Result.success(detachedTimeline))
+        val sut = TimelineController(matrixRoom)
+
+        sut.activeTimelineFlow().test {
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(liveTimeline)
+            }
+            sut.focusOnEvent(AN_EVENT_ID)
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(detachedTimeline)
+            }
+            val paginateLambda = lambdaRecorder { _: Timeline.PaginationDirection ->
+                Result.success(true)
+            }
+            detachedTimeline.apply {
+                this.paginateLambda = paginateLambda
+            }
+            sut.paginate(Timeline.PaginationDirection.FORWARDS)
+            awaitItem().also { state ->
+                assertThat(state).isEqualTo(liveTimeline)
+            }
+        }
+    }
+}

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/TimelineItemIndexerTest.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline
+
+import com.google.common.truth.Truth.assertThat
+import io.element.android.features.messages.impl.timeline.model.TimelineItem
+import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemReadMarkerModel
+import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.test.AN_EVENT_ID
+import org.junit.Test
+
+class TimelineItemIndexerTest {
+    @Test
+    fun `test TimelineItemIndexer`() {
+        val eventIds = mutableListOf<EventId>()
+        val data = listOf(
+            aTimelineItemEvent().also { eventIds.add(it.eventId!!) },
+            aTimelineItemEvent().also { eventIds.add(it.eventId!!) },
+            aGroupedEvents().also { groupedEvents ->
+                groupedEvents.events.forEach { eventIds.add(it.eventId!!) }
+            },
+            TimelineItem.Virtual(
+                id = "dummy",
+                model = TimelineItemReadMarkerModel
+            ),
+        )
+        assertThat(eventIds.size).isEqualTo(4)
+        val sut = TimelineItemIndexer()
+        sut.process(data)
+        eventIds.forEach {
+            assertThat(sut.isKnown(it)).isTrue()
+        }
+        assertThat(sut.indexOf(eventIds[0])).isEqualTo(0)
+        assertThat(sut.indexOf(eventIds[1])).isEqualTo(1)
+        assertThat(sut.indexOf(eventIds[2])).isEqualTo(2)
+        assertThat(sut.indexOf(eventIds[3])).isEqualTo(2)
+
+        // Unknown event
+        assertThat(sut.isKnown(AN_EVENT_ID)).isFalse()
+        assertThat(sut.indexOf(AN_EVENT_ID)).isEqualTo(-1)
+    }
+}

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/TimelinePresenterTest.kt

@@ -22,6 +22,7 @@ import app.cash.turbine.ReceiveTurbine
 import app.cash.turbine.test
 import com.google.common.truth.Truth.assertThat
 import io.element.android.features.messages.impl.FakeMessagesNavigator
+import io.element.android.features.messages.impl.fixtures.aMessageEvent
 import io.element.android.features.messages.impl.fixtures.aTimelineItemsFactory
 import io.element.android.features.messages.impl.timeline.factories.TimelineItemsFactory
 import io.element.android.features.messages.impl.timeline.model.NewEventState
@@ -33,12 +34,12 @@ import io.element.android.features.poll.api.actions.EndPollAction
 import io.element.android.features.poll.api.actions.SendPollResponseAction
 import io.element.android.features.poll.test.actions.FakeEndPollAction
 import io.element.android.features.poll.test.actions.FakeSendPollResponseAction
-import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.featureflag.test.InMemorySessionPreferencesStore
+import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.room.MatrixRoomMembersState
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
 import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
 import io.element.android.libraries.matrix.api.timeline.ReceiptType
+import io.element.android.libraries.matrix.api.timeline.Timeline
 import io.element.android.libraries.matrix.api.timeline.item.event.EventReaction
 import io.element.android.libraries.matrix.api.timeline.item.event.ReactionSender
 import io.element.android.libraries.matrix.api.timeline.item.event.Receipt
@@ -48,20 +49,27 @@ import io.element.android.libraries.matrix.test.AN_EVENT_ID_2
 import io.element.android.libraries.matrix.test.A_USER_ID
 import io.element.android.libraries.matrix.test.room.FakeMatrixRoom
 import io.element.android.libraries.matrix.test.room.aRoomMember
-import io.element.android.libraries.matrix.test.timeline.FakeMatrixTimeline
+import io.element.android.libraries.matrix.test.timeline.FakeTimeline
 import io.element.android.libraries.matrix.test.timeline.aMessageContent
 import io.element.android.libraries.matrix.test.timeline.anEventTimelineItem
 import io.element.android.libraries.matrix.ui.components.aMatrixUserList
 import io.element.android.tests.testutils.WarmUpRule
 import io.element.android.tests.testutils.awaitLastSequentialItem
-import io.element.android.tests.testutils.awaitWithLatch
 import io.element.android.tests.testutils.consumeItemsUntilPredicate
+import io.element.android.tests.testutils.lambda.any
+import io.element.android.tests.testutils.lambda.assert
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
 import io.element.android.tests.testutils.testCoroutineDispatchers
 import kotlinx.collections.immutable.persistentListOf
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.getAndUpdate
 import kotlinx.coroutines.test.StandardTestDispatcher
 import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.advanceUntilIdle
 import kotlinx.coroutines.test.runCurrent
 import kotlinx.coroutines.test.runTest
 import org.junit.Rule
@@ -72,7 +80,7 @@ import kotlin.time.Duration.Companion.seconds
 private const val FAKE_UNIQUE_ID = "FAKE_UNIQUE_ID"
 private const val FAKE_UNIQUE_ID_2 = "FAKE_UNIQUE_ID_2"
 
-class TimelinePresenterTest {
+@OptIn(ExperimentalCoroutinesApi::class) class TimelinePresenterTest {
     @get:Rule
     val warmUpRule = WarmUpRule()
 
@@ -84,58 +92,49 @@ class TimelinePresenterTest {
         }.test {
             val initialState = awaitFirstItem()
             assertThat(initialState.timelineItems).isEmpty()
-            val loadedNoTimelineState = awaitItem()
-            assertThat(loadedNoTimelineState.timelineItems).isEmpty()
+            assertThat(initialState.isLive).isTrue()
+            assertThat(initialState.newEventState).isEqualTo(NewEventState.None)
+            assertThat(initialState.focusedEventId).isNull()
+            assertThat(initialState.focusRequestState).isEqualTo(FocusRequestState.None)
         }
     }
 
     @Test
     fun `present - load more`() = runTest {
-        val presenter = createTimelinePresenter()
+        val paginateLambda = lambdaRecorder { _: Timeline.PaginationDirection ->
+            Result.success(false)
+        }
+        val timeline = FakeTimeline().apply {
+            this.paginateLambda = paginateLambda
+        }
+        val presenter = createTimelinePresenter(timeline = timeline)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
             val initialState = awaitItem()
-            assertThat(initialState.paginationState.hasMoreToLoadBackwards).isTrue()
-            assertThat(initialState.paginationState.isBackPaginating).isFalse()
-            initialState.eventSink.invoke(TimelineEvents.LoadMore)
-            val inPaginationState = awaitItem()
-            assertThat(inPaginationState.paginationState.isBackPaginating).isTrue()
-            assertThat(inPaginationState.paginationState.hasMoreToLoadBackwards).isTrue()
-            val postPaginationState = awaitItem()
-            assertThat(postPaginationState.paginationState.hasMoreToLoadBackwards).isTrue()
-            assertThat(postPaginationState.paginationState.isBackPaginating).isFalse()
-        }
-    }
-
-    @Test
-    fun `present - set highlighted event`() = runTest {
-        val presenter = createTimelinePresenter()
-        moleculeFlow(RecompositionMode.Immediate) {
-            presenter.present()
-        }.test {
-            val initialState = awaitFirstItem()
-            skipItems(1)
-            assertThat(initialState.highlightedEventId).isNull()
-            initialState.eventSink.invoke(TimelineEvents.SetHighlightedEvent(AN_EVENT_ID))
-            val withHighlightedState = awaitItem()
-            assertThat(withHighlightedState.highlightedEventId).isEqualTo(AN_EVENT_ID)
-            initialState.eventSink.invoke(TimelineEvents.SetHighlightedEvent(null))
-            val withoutHighlightedState = awaitItem()
-            assertThat(withoutHighlightedState.highlightedEventId).isNull()
+            initialState.eventSink.invoke(TimelineEvents.LoadMore(Timeline.PaginationDirection.BACKWARDS))
+            initialState.eventSink.invoke(TimelineEvents.LoadMore(Timeline.PaginationDirection.FORWARDS))
+            assert(paginateLambda)
+                .isCalledExactly(2)
+                .withSequence(
+                    listOf(value(Timeline.PaginationDirection.BACKWARDS)),
+                    listOf(value(Timeline.PaginationDirection.FORWARDS))
+                )
         }
     }
 
     @OptIn(ExperimentalCoroutinesApi::class)
     @Test
     fun `present - on scroll finished mark a room as read if the first visible index is 0`() = runTest(StandardTestDispatcher()) {
-        val timeline = FakeMatrixTimeline(
-            initialTimelineItems = listOf(
-                MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem())
+        val timeline = FakeTimeline(
+            timelineItems = flowOf(
+                listOf(
+                    MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem())
+                )
             )
         )
+        val room = FakeMatrixRoom(liveTimeline = timeline)
         val sessionPreferencesStore = InMemorySessionPreferencesStore(isSendPublicReadReceiptsEnabled = false)
-        val room = FakeMatrixRoom(matrixTimeline = timeline)
         val presenter = createTimelinePresenter(
             timeline = timeline,
             room = room,
@@ -144,7 +143,6 @@ class TimelinePresenterTest {
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            assertThat(timeline.sentReadReceipts).isEmpty()
             val initialState = awaitFirstItem()
             initialState.eventSink.invoke(TimelineEvents.OnScrollFinished(0))
             runCurrent()
@@ -155,48 +153,62 @@ class TimelinePresenterTest {
 
     @Test
     fun `present - on scroll finished send read receipt if an event is before the index`() = runTest {
-        val timeline = FakeMatrixTimeline(
-            initialTimelineItems = listOf(
-                MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem()),
-                MatrixTimelineItem.Event(
-                    uniqueId = FAKE_UNIQUE_ID_2,
-                    event = anEventTimelineItem(
-                        eventId = AN_EVENT_ID_2,
-                        content = aMessageContent("Test message")
+        val sendReadReceiptsLambda = lambdaRecorder { _: EventId, _: ReceiptType ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline(
+            timelineItems = flowOf(
+                listOf(
+                    MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem()),
+                    MatrixTimelineItem.Event(
+                        uniqueId = FAKE_UNIQUE_ID_2,
+                        event = anEventTimelineItem(
+                            eventId = AN_EVENT_ID_2,
+                            content = aMessageContent("Test message")
+                        )
                     )
                 )
             )
-        )
+        ).apply {
+            this.sendReadReceiptLambda = sendReadReceiptsLambda
+        }
         val presenter = createTimelinePresenter(timeline)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            assertThat(timeline.sentReadReceipts).isEmpty()
-            val initialState = awaitFirstItem()
-            awaitWithLatch { latch ->
-                timeline.sendReadReceiptLatch = latch
-                initialState.eventSink.invoke(TimelineEvents.OnScrollFinished(1))
+            skipItems(1)
+            awaitItem().run {
+                eventSink.invoke(TimelineEvents.OnScrollFinished(1))
             }
-            assertThat(timeline.sentReadReceipts).isNotEmpty()
-            assertThat(timeline.sentReadReceipts.first().second).isEqualTo(ReceiptType.READ)
+            advanceUntilIdle()
+            assert(sendReadReceiptsLambda)
+                .isCalledOnce()
+                .with(any(), value(ReceiptType.READ))
             cancelAndIgnoreRemainingEvents()
         }
     }
 
     @Test
     fun `present - on scroll finished send a private read receipt if an event is at an index other than 0 and public read receipts are disabled`() = runTest {
-        val timeline = FakeMatrixTimeline(
-            initialTimelineItems = listOf(
-                MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem()),
-                MatrixTimelineItem.Event(
-                    uniqueId = FAKE_UNIQUE_ID_2,
-                    event = anEventTimelineItem(
-                        eventId = AN_EVENT_ID_2,
-                        content = aMessageContent("Test message")
+        val sendReadReceiptsLambda = lambdaRecorder { _: EventId, _: ReceiptType ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline(
+            timelineItems = flowOf(
+                listOf(
+                    MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem()),
+                    MatrixTimelineItem.Event(
+                        uniqueId = FAKE_UNIQUE_ID_2,
+                        event = anEventTimelineItem(
+                            eventId = AN_EVENT_ID_2,
+                            content = aMessageContent("Test message")
+                        )
                     )
                 )
             )
-        )
+        ).apply {
+            this.sendReadReceiptLambda = sendReadReceiptsLambda
+        }
         val sessionPreferencesStore = InMemorySessionPreferencesStore(isSendPublicReadReceiptsEnabled = false)
         val presenter = createTimelinePresenter(
             timeline = timeline,
@@ -205,75 +217,86 @@ class TimelinePresenterTest {
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            assertThat(timeline.sentReadReceipts).isEmpty()
-            val initialState = awaitFirstItem()
-            awaitWithLatch { latch ->
-                timeline.sendReadReceiptLatch = latch
-                initialState.eventSink.invoke(TimelineEvents.OnScrollFinished(0))
-                initialState.eventSink.invoke(TimelineEvents.OnScrollFinished(1))
+            skipItems(1)
+            awaitItem().run {
+                eventSink.invoke(TimelineEvents.OnScrollFinished(0))
+                eventSink.invoke(TimelineEvents.OnScrollFinished(1))
             }
-            assertThat(timeline.sentReadReceipts).isNotEmpty()
-            assertThat(timeline.sentReadReceipts.first().second).isEqualTo(ReceiptType.READ_PRIVATE)
+            advanceUntilIdle()
+            assert(sendReadReceiptsLambda)
+                .isCalledOnce()
+                .with(any(), value(ReceiptType.READ_PRIVATE))
             cancelAndIgnoreRemainingEvents()
         }
     }
 
     @Test
     fun `present - on scroll finished will not send read receipt the first visible event is the same as before`() = runTest {
-        val timeline = FakeMatrixTimeline(
-            initialTimelineItems = listOf(
-                MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem()),
-                MatrixTimelineItem.Event(
-                    uniqueId = FAKE_UNIQUE_ID_2,
-                    event = anEventTimelineItem(
-                        eventId = AN_EVENT_ID_2,
-                        content = aMessageContent("Test message")
+        val sendReadReceiptsLambda = lambdaRecorder { _: EventId, _: ReceiptType ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline(
+            timelineItems = flowOf(
+                listOf(
+                    MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem()),
+                    MatrixTimelineItem.Event(
+                        uniqueId = FAKE_UNIQUE_ID_2,
+                        event = anEventTimelineItem(
+                            eventId = AN_EVENT_ID_2,
+                            content = aMessageContent("Test message")
+                        )
                     )
                 )
             )
-        )
+        ).apply {
+            this.sendReadReceiptLambda = sendReadReceiptsLambda
+        }
         val presenter = createTimelinePresenter(timeline)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            assertThat(timeline.sentReadReceipts).isEmpty()
-            val initialState = awaitFirstItem()
-            awaitWithLatch { latch ->
-                timeline.sendReadReceiptLatch = latch
-                initialState.eventSink.invoke(TimelineEvents.OnScrollFinished(1))
-                initialState.eventSink.invoke(TimelineEvents.OnScrollFinished(1))
+            skipItems(1)
+            awaitItem().run {
+                eventSink.invoke(TimelineEvents.OnScrollFinished(1))
+                eventSink.invoke(TimelineEvents.OnScrollFinished(1))
             }
-            assertThat(timeline.sentReadReceipts).hasSize(1)
+            advanceUntilIdle()
             cancelAndIgnoreRemainingEvents()
+            assert(sendReadReceiptsLambda).isCalledOnce()
         }
     }
 
     @Test
     fun `present - on scroll finished will not send read receipt only virtual events exist before the index`() = runTest {
-        val timeline = FakeMatrixTimeline(
-            initialTimelineItems = listOf(
-                MatrixTimelineItem.Virtual(FAKE_UNIQUE_ID, VirtualTimelineItem.ReadMarker),
-                MatrixTimelineItem.Virtual(FAKE_UNIQUE_ID, VirtualTimelineItem.ReadMarker)
+        val sendReadReceiptsLambda = lambdaRecorder { _: EventId, _: ReceiptType ->
+            Result.success(Unit)
+        }
+        val timeline = FakeTimeline(
+            timelineItems = flowOf(
+                listOf(
+                    MatrixTimelineItem.Virtual(FAKE_UNIQUE_ID, VirtualTimelineItem.ReadMarker),
+                    MatrixTimelineItem.Virtual(FAKE_UNIQUE_ID, VirtualTimelineItem.ReadMarker)
+                )
             )
-        )
+        ).apply {
+            this.sendReadReceiptLambda = sendReadReceiptsLambda
+        }
         val presenter = createTimelinePresenter(timeline)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            assertThat(timeline.sentReadReceipts).isEmpty()
+            skipItems(1)
             val initialState = awaitFirstItem()
-            awaitWithLatch { latch ->
-                timeline.sendReadReceiptLatch = latch
-                initialState.eventSink.invoke(TimelineEvents.OnScrollFinished(1))
-            }
-            assertThat(timeline.sentReadReceipts).isEmpty()
+            initialState.eventSink.invoke(TimelineEvents.OnScrollFinished(1))
             cancelAndIgnoreRemainingEvents()
+            assert(sendReadReceiptsLambda).isNeverCalled()
         }
     }
 
     @Test
     fun `present - covers newEventState scenarios`() = runTest {
-        val timeline = FakeMatrixTimeline()
+        val timelineItems = MutableStateFlow(emptyList<MatrixTimelineItem>())
+        val timeline = FakeTimeline(timelineItems = timelineItems)
         val presenter = createTimelinePresenter(timeline)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
@@ -281,12 +304,12 @@ class TimelinePresenterTest {
             val initialState = awaitFirstItem()
             assertThat(initialState.newEventState).isEqualTo(NewEventState.None)
             assertThat(initialState.timelineItems.size).isEqualTo(0)
-            timeline.updateTimelineItems {
+            timelineItems.emit(
                 listOf(MatrixTimelineItem.Event("0", anEventTimelineItem(content = aMessageContent())))
-            }
+            )
             consumeItemsUntilPredicate { it.timelineItems.size == 1 }
             // Mimics sending a message, and assert newEventState is FromMe
-            timeline.updateTimelineItems { items ->
+            timelineItems.getAndUpdate { items ->
                 val event = anEventTimelineItem(content = aMessageContent(), isOwn = true)
                 items + listOf(MatrixTimelineItem.Event("1", event))
             }
@@ -295,7 +318,7 @@ class TimelinePresenterTest {
                 assertThat(state.newEventState).isEqualTo(NewEventState.FromMe)
             }
             // Mimics receiving a message without clearing the previous FromMe
-            timeline.updateTimelineItems { items ->
+            timelineItems.getAndUpdate { items ->
                 val event = anEventTimelineItem(content = aMessageContent())
                 items + listOf(MatrixTimelineItem.Event("2", event))
             }
@@ -307,7 +330,7 @@ class TimelinePresenterTest {
                 assertThat(state.newEventState).isEqualTo(NewEventState.None)
             }
             // Mimics receiving a message and assert newEventState is FromOther
-            timeline.updateTimelineItems { items ->
+            timelineItems.getAndUpdate { items ->
                 val event = anEventTimelineItem(content = aMessageContent())
                 items + listOf(MatrixTimelineItem.Event("3", event))
             }
@@ -321,7 +344,10 @@ class TimelinePresenterTest {
 
     @Test
     fun `present - reaction ordering`() = runTest {
-        val timeline = FakeMatrixTimeline()
+        val timelineItems = MutableStateFlow(emptyList<MatrixTimelineItem>())
+        val timeline = FakeTimeline(
+            timelineItems = timelineItems,
+        )
         val presenter = createTimelinePresenter(timeline)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
@@ -349,10 +375,9 @@ class TimelinePresenterTest {
                     senders = persistentListOf(charlie)
                 ),
             )
-            timeline.updateTimelineItems {
+            timelineItems.emit(
                 listOf(MatrixTimelineItem.Event(FAKE_UNIQUE_ID, anEventTimelineItem(reactions = oneReaction)))
-            }
-            skipItems(1)
+            )
             val item = awaitItem().timelineItems.first()
             assertThat(item).isInstanceOf(TimelineItem.Event::class.java)
             val event = item as TimelineItem.Event
@@ -424,8 +449,10 @@ class TimelinePresenterTest {
     fun `present - side effect on redacted items is invoked`() = runTest {
         val redactedVoiceMessageManager = FakeRedactedVoiceMessageManager()
         val presenter = createTimelinePresenter(
-            timeline = FakeMatrixTimeline(
-                initialTimelineItems = aRedactedMatrixTimeline(AN_EVENT_ID),
+            timeline = FakeTimeline(
+                timelineItems = flowOf(
+                    aRedactedMatrixTimeline(AN_EVENT_ID),
+                )
             ),
             redactedVoiceMessageManager = redactedVoiceMessageManager,
         )
@@ -433,32 +460,141 @@ class TimelinePresenterTest {
             presenter.present()
         }.test {
             assertThat(redactedVoiceMessageManager.invocations.size).isEqualTo(0)
-            awaitFirstItem().let {
-                assertThat(it.timelineItems).isNotEmpty()
-            }
+            skipItems(2)
             assertThat(redactedVoiceMessageManager.invocations.size).isEqualTo(1)
         }
     }
 
+    @Test
+    fun `present - focus on event and jump to live make the presenter update the state with the correct Events`() = runTest {
+        val detachedTimeline = FakeTimeline(
+            timelineItems = flowOf(
+                listOf(
+                    MatrixTimelineItem.Event(
+                        uniqueId = FAKE_UNIQUE_ID,
+                        event = anEventTimelineItem(),
+                    )
+                )
+            )
+        )
+        val liveTimeline = FakeTimeline(
+            timelineItems = flowOf(emptyList())
+        )
+        val room = FakeMatrixRoom(
+            liveTimeline = liveTimeline,
+        ).apply {
+            givenTimelineFocusedOnEventResult(Result.success(detachedTimeline))
+        }
+        val presenter = createTimelinePresenter(
+            room = room,
+        )
+        moleculeFlow(RecompositionMode.Immediate) {
+            presenter.present()
+        }.test {
+            val initialState = awaitFirstItem()
+            initialState.eventSink.invoke(TimelineEvents.FocusOnEvent(AN_EVENT_ID))
+            awaitItem().also { state ->
+                assertThat(state.focusedEventId).isEqualTo(AN_EVENT_ID)
+                assertThat(state.focusRequestState).isEqualTo(FocusRequestState.Fetching)
+            }
+            skipItems(2)
+            awaitItem().also { state ->
+                assertThat(state.focusRequestState).isEqualTo(FocusRequestState.Fetched)
+                assertThat(state.timelineItems).isNotEmpty()
+            }
+            initialState.eventSink.invoke(TimelineEvents.JumpToLive)
+            skipItems(1)
+            awaitItem().also { state ->
+                // Event stays focused
+                assertThat(state.focusedEventId).isEqualTo(AN_EVENT_ID)
+                assertThat(state.timelineItems).isEmpty()
+            }
+        }
+    }
+
+    @Test
+    fun `present - focus on known event retrieves the event from cache`() = runTest {
+        val timelineItemIndexer = TimelineItemIndexer().apply {
+            process(listOf(aMessageEvent(eventId = AN_EVENT_ID)))
+        }
+        val presenter = createTimelinePresenter(
+            room = FakeMatrixRoom(
+                liveTimeline = FakeTimeline(
+                    timelineItems = flowOf(
+                        listOf(
+                            MatrixTimelineItem.Event(
+                                uniqueId = FAKE_UNIQUE_ID,
+                                event = anEventTimelineItem(eventId = AN_EVENT_ID),
+                            )
+                        )
+                    )
+                ),
+            ),
+            timelineItemIndexer = timelineItemIndexer,
+        )
+        moleculeFlow(RecompositionMode.Immediate) {
+            presenter.present()
+        }.test {
+            val initialState = awaitFirstItem()
+            initialState.eventSink.invoke(TimelineEvents.FocusOnEvent(AN_EVENT_ID))
+            awaitItem().also { state ->
+                assertThat(state.focusedEventId).isEqualTo(AN_EVENT_ID)
+                assertThat(state.focusRequestState).isEqualTo(FocusRequestState.Cached(0))
+            }
+        }
+    }
+
+    @Test
+    fun `present - focus on event error case`() = runTest {
+        val presenter = createTimelinePresenter(
+            room = FakeMatrixRoom(
+                liveTimeline = FakeTimeline(
+                    timelineItems = flowOf(emptyList()),
+                ),
+            ).apply {
+                givenTimelineFocusedOnEventResult(Result.failure(Throwable("An error")))
+            },
+        )
+        moleculeFlow(RecompositionMode.Immediate) {
+            presenter.present()
+        }.test {
+            val initialState = awaitFirstItem()
+            initialState.eventSink(TimelineEvents.FocusOnEvent(AN_EVENT_ID))
+            awaitItem().also { state ->
+                assertThat(state.focusedEventId).isEqualTo(AN_EVENT_ID)
+                assertThat(state.focusRequestState).isEqualTo(FocusRequestState.Fetching)
+            }
+            awaitItem().also { state ->
+                assertThat(state.focusRequestState).isInstanceOf(FocusRequestState.Failure::class.java)
+                state.eventSink(TimelineEvents.ClearFocusRequestState)
+            }
+            awaitItem().also { state ->
+                assertThat(state.focusRequestState).isEqualTo(FocusRequestState.None)
+            }
+        }
+    }
+
     @Test
     fun `present - when room member info is loaded, read receipts info should be updated`() = runTest {
-        val timeline = FakeMatrixTimeline(
-            listOf(
-                MatrixTimelineItem.Event(
-                    FAKE_UNIQUE_ID,
-                    anEventTimelineItem(
-                        sender = A_USER_ID,
-                        receipts = persistentListOf(
-                            Receipt(
-                                userId = A_USER_ID,
-                                timestamp = 0L,
+        val timeline = FakeTimeline(
+            timelineItems = flowOf(
+                listOf(
+                    MatrixTimelineItem.Event(
+                        FAKE_UNIQUE_ID,
+                        anEventTimelineItem(
+                            sender = A_USER_ID,
+                            receipts = persistentListOf(
+                                Receipt(
+                                    userId = A_USER_ID,
+                                    timestamp = 0L,
+                                )
                             )
                         )
                     )
                 )
             )
         )
-        val room = FakeMatrixRoom(matrixTimeline = timeline).apply {
+        val room = FakeMatrixRoom(liveTimeline = timeline).apply {
             givenRoomMembersState(MatrixRoomMembersState.Unknown)
         }
 
@@ -485,22 +621,19 @@ class TimelinePresenterTest {
     }
 
     private suspend fun <T> ReceiveTurbine<T>.awaitFirstItem(): T {
-        // Skip 1 item if Mentions feature is enabled
-        if (FeatureFlags.Mentions.defaultValue) {
-            skipItems(1)
-        }
         return awaitItem()
     }
 
     private fun TestScope.createTimelinePresenter(
-        timeline: MatrixTimeline = FakeMatrixTimeline(),
-        room: FakeMatrixRoom = FakeMatrixRoom(matrixTimeline = timeline),
+        timeline: Timeline = FakeTimeline(),
+        room: FakeMatrixRoom = FakeMatrixRoom(liveTimeline = timeline),
         timelineItemsFactory: TimelineItemsFactory = aTimelineItemsFactory(),
         redactedVoiceMessageManager: RedactedVoiceMessageManager = FakeRedactedVoiceMessageManager(),
         messagesNavigator: FakeMessagesNavigator = FakeMessagesNavigator(),
         endPollAction: EndPollAction = FakeEndPollAction(),
         sendPollResponseAction: SendPollResponseAction = FakeSendPollResponseAction(),
         sessionPreferencesStore: InMemorySessionPreferencesStore = InMemorySessionPreferencesStore(),
+        timelineItemIndexer: TimelineItemIndexer = TimelineItemIndexer(),
     ): TimelinePresenter {
         return TimelinePresenter(
             timelineItemsFactory = timelineItemsFactory,
@@ -512,6 +645,8 @@ class TimelinePresenterTest {
             endPollAction = endPollAction,
             sendPollResponseAction = sendPollResponseAction,
             sessionPreferencesStore = sessionPreferencesStore,
+            timelineItemIndexer = timelineItemIndexer,
+            timelineController = TimelineController(room),
         )
     }
 }

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/TimelineViewTest.kt

@@ -17,14 +17,25 @@
 package io.element.android.features.messages.impl.timeline
 
 import androidx.activity.ComponentActivity
+import androidx.compose.ui.test.junit4.AndroidComposeTestRule
 import androidx.compose.ui.test.junit4.createAndroidComposeRule
+import androidx.compose.ui.test.onNodeWithContentDescription
+import androidx.compose.ui.test.performClick
 import androidx.test.ext.junit.runners.AndroidJUnit4
+import io.element.android.features.messages.impl.timeline.model.TimelineItem
+import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemLoadingIndicatorModel
+import io.element.android.features.messages.impl.typing.TypingNotificationState
 import io.element.android.features.messages.impl.typing.aTypingNotificationState
+import io.element.android.libraries.matrix.api.core.UserId
+import io.element.android.libraries.matrix.api.timeline.Timeline
+import io.element.android.libraries.ui.strings.CommonStrings
 import io.element.android.tests.testutils.EnsureNeverCalledWithParam
 import io.element.android.tests.testutils.EnsureNeverCalledWithTwoParams
 import io.element.android.tests.testutils.EventsRecorder
+import kotlinx.collections.immutable.persistentListOf
 import org.junit.Rule
 import org.junit.Test
+import org.junit.rules.TestRule
 import org.junit.runner.RunWith
 
 @RunWith(AndroidJUnit4::class)
@@ -34,55 +45,89 @@ class TimelineViewTest {
     @Test
     fun `reaching the end of the timeline with more events to load emits a LoadMore event`() {
         val eventsRecorder = EventsRecorder<TimelineEvents>()
-        rule.setContent {
-            TimelineView(
-                aTimelineState(
-                    eventSink = eventsRecorder,
-                    paginationState = aPaginationState(
-                        hasMoreToLoadBackwards = true,
-                    )
+        rule.setTimelineView(
+            state = aTimelineState(
+                timelineItems = persistentListOf<TimelineItem>(
+                    TimelineItem.Virtual(
+                        id = "backward_pagination",
+                        model = TimelineItemLoadingIndicatorModel(Timeline.PaginationDirection.BACKWARDS, 0)
+                    ),
                 ),
-                typingNotificationState = aTypingNotificationState(),
-                roomName = null,
-                onUserDataClicked = EnsureNeverCalledWithParam(),
-                onLinkClicked = EnsureNeverCalledWithParam(),
-                onMessageClicked = EnsureNeverCalledWithParam(),
-                onMessageLongClicked = EnsureNeverCalledWithParam(),
-                onTimestampClicked = EnsureNeverCalledWithParam(),
-                onSwipeToReply = EnsureNeverCalledWithParam(),
-                onReactionClicked = EnsureNeverCalledWithTwoParams(),
-                onReactionLongClicked = EnsureNeverCalledWithTwoParams(),
-                onMoreReactionsClicked = EnsureNeverCalledWithParam(),
-                onReadReceiptClick = EnsureNeverCalledWithParam(),
-            )
-        }
-        eventsRecorder.assertSingle(TimelineEvents.LoadMore)
+                eventSink = eventsRecorder,
+            ),
+        )
+        eventsRecorder.assertSingle(TimelineEvents.LoadMore(Timeline.PaginationDirection.BACKWARDS))
     }
 
     @Test
     fun `reaching the end of the timeline does not send a LoadMore event`() {
         val eventsRecorder = EventsRecorder<TimelineEvents>(expectEvents = false)
-        rule.setContent {
-            TimelineView(
-                aTimelineState(
-                    eventSink = eventsRecorder,
-                    paginationState = aPaginationState(
-                        hasMoreToLoadBackwards = false,
-                    )
-                ),
-                typingNotificationState = aTypingNotificationState(),
-                roomName = null,
-                onUserDataClicked = EnsureNeverCalledWithParam(),
-                onLinkClicked = EnsureNeverCalledWithParam(),
-                onMessageClicked = EnsureNeverCalledWithParam(),
-                onMessageLongClicked = EnsureNeverCalledWithParam(),
-                onTimestampClicked = EnsureNeverCalledWithParam(),
-                onSwipeToReply = EnsureNeverCalledWithParam(),
-                onReactionClicked = EnsureNeverCalledWithTwoParams(),
-                onReactionLongClicked = EnsureNeverCalledWithTwoParams(),
-                onMoreReactionsClicked = EnsureNeverCalledWithParam(),
-                onReadReceiptClick = EnsureNeverCalledWithParam(),
-            )
-        }
+        rule.setTimelineView(
+            state = aTimelineState(
+                eventSink = eventsRecorder,
+            ),
+        )
+    }
+
+    @Test
+    fun `scroll to bottom on live timeline does not emit the Event`() {
+        val eventsRecorder = EventsRecorder<TimelineEvents>(expectEvents = false)
+        rule.setTimelineView(
+            state = aTimelineState(
+                isLive = true,
+                eventSink = eventsRecorder,
+            ),
+            forceJumpToBottomVisibility = true,
+        )
+        val contentDescription = rule.activity.getString(CommonStrings.a11y_jump_to_bottom)
+        rule.onNodeWithContentDescription(contentDescription).performClick()
+    }
+
+    @Test
+    fun `scroll to bottom on detached timeline emits the expected Event`() {
+        val eventsRecorder = EventsRecorder<TimelineEvents>()
+        rule.setTimelineView(
+            state = aTimelineState(
+                isLive = false,
+                eventSink = eventsRecorder,
+            ),
+        )
+        val contentDescription = rule.activity.getString(CommonStrings.a11y_jump_to_bottom)
+        rule.onNodeWithContentDescription(contentDescription).performClick()
+        eventsRecorder.assertSingle(TimelineEvents.JumpToLive)
+    }
+}
+
+private fun <R : TestRule> AndroidComposeTestRule<R, ComponentActivity>.setTimelineView(
+    state: TimelineState,
+    typingNotificationState: TypingNotificationState = aTypingNotificationState(),
+    onUserDataClicked: (UserId) -> Unit = EnsureNeverCalledWithParam(),
+    onLinkClicked: (String) -> Unit = EnsureNeverCalledWithParam(),
+    onMessageClicked: (TimelineItem.Event) -> Unit = EnsureNeverCalledWithParam(),
+    onMessageLongClicked: (TimelineItem.Event) -> Unit = EnsureNeverCalledWithParam(),
+    onTimestampClicked: (TimelineItem.Event) -> Unit = EnsureNeverCalledWithParam(),
+    onSwipeToReply: (TimelineItem.Event) -> Unit = EnsureNeverCalledWithParam(),
+    onReactionClicked: (emoji: String, TimelineItem.Event) -> Unit = EnsureNeverCalledWithTwoParams(),
+    onReactionLongClicked: (emoji: String, TimelineItem.Event) -> Unit = EnsureNeverCalledWithTwoParams(),
+    onMoreReactionsClicked: (TimelineItem.Event) -> Unit = EnsureNeverCalledWithParam(),
+    onReadReceiptClick: (TimelineItem.Event) -> Unit = EnsureNeverCalledWithParam(),
+    forceJumpToBottomVisibility: Boolean = false,
+) {
+    setContent {
+        TimelineView(
+            state = state,
+            typingNotificationState = typingNotificationState,
+            onUserDataClicked = onUserDataClicked,
+            onLinkClicked = onLinkClicked,
+            onMessageClicked = onMessageClicked,
+            onMessageLongClicked = onMessageLongClicked,
+            onTimestampClicked = onTimestampClicked,
+            onSwipeToReply = onSwipeToReply,
+            onReactionClicked = onReactionClicked,
+            onReactionLongClicked = onReactionLongClicked,
+            onMoreReactionsClicked = onMoreReactionsClicked,
+            onReadReceiptClick = onReadReceiptClick,
+            forceJumpToBottomVisibility = forceJumpToBottomVisibility,
+        )
     }
 }

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/model/InReplyToDetailTest.kt

@@ -32,22 +32,22 @@ import org.junit.Test
 
 class InReplyToDetailTest {
     @Test
-    fun `map - with a not ready InReplyTo does not work`() {
+    fun `map - with a not ready InReplyTo return expected object`() {
         assertThat(
-            InReplyTo.Pending.map(
+            InReplyTo.Pending(AN_EVENT_ID).map(
                 permalinkParser = FakePermalinkParser()
             )
-        ).isNull()
+        ).isEqualTo(InReplyToDetails.Loading(AN_EVENT_ID))
         assertThat(
             InReplyTo.NotLoaded(AN_EVENT_ID).map(
                 permalinkParser = FakePermalinkParser()
             )
-        ).isNull()
+        ).isEqualTo(InReplyToDetails.Loading(AN_EVENT_ID))
         assertThat(
-            InReplyTo.Error.map(
+            InReplyTo.Error(AN_EVENT_ID, "a message").map(
                 permalinkParser = FakePermalinkParser()
             )
-        ).isNull()
+        ).isEqualTo(InReplyToDetails.Error(AN_EVENT_ID, "a message"))
     }
 
     @Test
@@ -65,7 +65,7 @@ class InReplyToDetailTest {
             permalinkParser = FakePermalinkParser()
         )
         assertThat(inReplyToDetails).isNotNull()
-        assertThat(inReplyToDetails?.textContent).isNull()
+        assertThat((inReplyToDetails as InReplyToDetails.Ready).textContent).isNull()
     }
 
     @Test
@@ -89,9 +89,7 @@ class InReplyToDetailTest {
             )
         )
         assertThat(
-            inReplyTo.map(
-                permalinkParser = FakePermalinkParser()
-            )?.textContent
+            (inReplyTo.map(permalinkParser = FakePermalinkParser()) as InReplyToDetails.Ready).textContent
         ).isEqualTo("Hello!")
     }
 
@@ -113,9 +111,7 @@ class InReplyToDetailTest {
             )
         )
         assertThat(
-            inReplyTo.map(
-                permalinkParser = FakePermalinkParser()
-            )?.textContent
+            (inReplyTo.map(permalinkParser = FakePermalinkParser()) as InReplyToDetails.Ready).textContent
         ).isEqualTo("**Hello!**")
     }
 }

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/model/InReplyToMetadataKtTest.kt

@@ -70,7 +70,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `any message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(eventContent = aMessageContent()).metadata()
+            anInReplyToDetailsReady(eventContent = aMessageContent()).metadata()
         }.test {
             awaitItem().let {
                 assertThat(it).isEqualTo(InReplyToMetadata.Text("textContent"))
@@ -81,7 +81,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `an image message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = aMessageContent(
                     messageType = ImageMessageType(
                         body = "body",
@@ -111,7 +111,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `a sticker message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = StickerContent(
                     body = "body",
                     info = anImageInfo(),
@@ -137,7 +137,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `a video message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = aMessageContent(
                     messageType = VideoMessageType(
                         body = "body",
@@ -167,7 +167,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `a file message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = aMessageContent(
                     messageType = FileMessageType(
                         body = "body",
@@ -200,7 +200,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `a audio message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = aMessageContent(
                     messageType = AudioMessageType(
                         body = "body",
@@ -232,7 +232,7 @@ class InReplyToMetadataKtTest {
     fun `a location message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
             testEnv {
-                anInReplyToDetails(
+                anInReplyToDetailsReady(
                     eventContent = aMessageContent(
                         messageType = LocationMessageType(
                             body = "body",
@@ -262,7 +262,7 @@ class InReplyToMetadataKtTest {
     fun `a voice message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
             testEnv {
-                anInReplyToDetails(
+                anInReplyToDetailsReady(
                     eventContent = aMessageContent(
                         messageType = VoiceMessageType(
                             body = "body",
@@ -292,7 +292,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `a poll content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = aPollContent()
             ).metadata()
         }.test {
@@ -314,7 +314,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `redacted content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = RedactedContent
             ).metadata()
         }.test {
@@ -327,7 +327,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `unable to decrypt content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = UnableToDecryptContent(UnableToDecryptContent.Data.Unknown)
             ).metadata()
         }.test {
@@ -340,7 +340,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `failed to parse message content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = FailedToParseMessageLikeContent("", "")
             ).metadata()
         }.test {
@@ -353,7 +353,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `failed to parse state content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = FailedToParseStateContent("", "", "")
             ).metadata()
         }.test {
@@ -366,7 +366,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `profile change content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = ProfileChangeContent("", "", "", "")
             ).metadata()
         }.test {
@@ -379,7 +379,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `room membership content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = RoomMembershipContent(A_USER_ID, null)
             ).metadata()
         }.test {
@@ -392,7 +392,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `state content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = StateContent("", OtherState.RoomJoinRules)
             ).metadata()
         }.test {
@@ -405,7 +405,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `unknown content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = UnknownContent
             ).metadata()
         }.test {
@@ -418,7 +418,7 @@ class InReplyToMetadataKtTest {
     @Test
     fun `null content`() = runTest {
         moleculeFlow(RecompositionMode.Immediate) {
-            anInReplyToDetails(
+            anInReplyToDetailsReady(
                 eventContent = null
             ).metadata()
         }.test {
@@ -429,13 +429,13 @@ class InReplyToMetadataKtTest {
     }
 }
 
-fun anInReplyToDetails(
+private fun anInReplyToDetailsReady(
     eventId: EventId = AN_EVENT_ID,
     senderId: UserId = A_USER_ID,
     senderProfile: ProfileTimelineDetails = aProfileTimelineDetails(),
     eventContent: EventContent? = aMessageContent(),
     textContent: String? = "textContent",
-) = InReplyToDetails(
+) = InReplyToDetails.Ready(
     eventId = eventId,
     senderId = senderId,
     senderProfile = senderProfile,

features/poll/impl/src/main/kotlin/io/element/android/features/poll/impl/data/PollRepository.kt

@@ -20,15 +20,19 @@ import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.poll.PollKind
 import io.element.android.libraries.matrix.api.room.MatrixRoom
 import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.TimelineProvider
+import io.element.android.libraries.matrix.api.timeline.getActiveTimeline
 import io.element.android.libraries.matrix.api.timeline.item.event.PollContent
 import kotlinx.coroutines.flow.first
 import javax.inject.Inject
 
 class PollRepository @Inject constructor(
     private val room: MatrixRoom,
+    private val timelineProvider: TimelineProvider,
 ) {
     suspend fun getPoll(eventId: EventId): Result<PollContent> = runCatching {
-        room.timeline
+        timelineProvider
+            .getActiveTimeline()
             .timelineItems
             .first()
             .asSequence()
@@ -51,13 +55,15 @@ class PollRepository @Inject constructor(
             maxSelections = maxSelections,
             pollKind = pollKind,
         )
-        else -> room.editPoll(
-            pollStartId = existingPollId,
-            question = question,
-            answers = answers,
-            maxSelections = maxSelections,
-            pollKind = pollKind,
-        )
+        else -> timelineProvider
+            .getActiveTimeline()
+            .editPoll(
+                pollStartId = existingPollId,
+                question = question,
+                answers = answers,
+                maxSelections = maxSelections,
+                pollKind = pollKind,
+            )
     }
 
     suspend fun deletePoll(

features/poll/impl/src/main/kotlin/io/element/android/features/poll/impl/history/PollHistoryPresenter.kt

@@ -32,25 +32,24 @@ import io.element.android.features.poll.impl.history.model.PollHistoryFilter
 import io.element.android.features.poll.impl.history.model.PollHistoryItems
 import io.element.android.features.poll.impl.history.model.PollHistoryItemsFactory
 import io.element.android.libraries.architecture.Presenter
-import io.element.android.libraries.matrix.api.room.MatrixRoom
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
+import io.element.android.libraries.matrix.api.timeline.Timeline
+import io.element.android.libraries.matrix.api.timeline.TimelineProvider
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
 class PollHistoryPresenter @Inject constructor(
-    private val room: MatrixRoom,
     private val appCoroutineScope: CoroutineScope,
     private val sendPollResponseAction: SendPollResponseAction,
     private val endPollAction: EndPollAction,
     private val pollHistoryItemFactory: PollHistoryItemsFactory,
+    private val timelineProvider: TimelineProvider,
 ) : Presenter<PollHistoryState> {
     @Composable
     override fun present(): PollHistoryState {
-        // TODO use room.rememberPollHistory() when working properly?
-        val timeline = room.timeline
-        val paginationState by timeline.paginationState.collectAsState()
+        val timeline by timelineProvider.activeTimelineFlow().collectAsState()
+        val paginationState by timeline.paginationStatus(Timeline.PaginationDirection.BACKWARDS).collectAsState()
         val pollHistoryItemsFlow = remember {
             timeline.timelineItems.map { items ->
                 pollHistoryItemFactory.create(items)
@@ -61,11 +60,11 @@ class PollHistoryPresenter @Inject constructor(
         }
         val pollHistoryItems by pollHistoryItemsFlow.collectAsState(initial = PollHistoryItems())
         LaunchedEffect(paginationState, pollHistoryItems.size) {
-            if (pollHistoryItems.size == 0 && paginationState.canBackPaginate) loadMore(timeline)
+            if (pollHistoryItems.size == 0 && paginationState.canPaginate) loadMore(timeline)
         }
         val isLoading by remember {
             derivedStateOf {
-                pollHistoryItems.size == 0 || paginationState.isBackPaginating
+                pollHistoryItems.size == 0 || paginationState.isPaginating
             }
         }
         val coroutineScope = rememberCoroutineScope()
@@ -88,14 +87,14 @@ class PollHistoryPresenter @Inject constructor(
 
         return PollHistoryState(
             isLoading = isLoading,
-            hasMoreToLoad = paginationState.hasMoreToLoadBackwards,
+            hasMoreToLoad = paginationState.hasMoreToLoad,
             pollHistoryItems = pollHistoryItems,
             activeFilter = activeFilter,
             eventSink = ::handleEvents,
         )
     }
 
-    private fun CoroutineScope.loadMore(pollHistory: MatrixTimeline) = launch {
-        pollHistory.paginateBackwards(200)
+    private fun CoroutineScope.loadMore(pollHistory: Timeline) = launch {
+        pollHistory.paginate(Timeline.PaginationDirection.BACKWARDS)
     }
 }

features/poll/impl/src/test/kotlin/io/element/android/features/poll/impl/PollFixtures.kt

@@ -20,16 +20,17 @@ import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.poll.PollAnswer
 import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
 import io.element.android.libraries.matrix.api.timeline.item.event.PollContent
-import io.element.android.libraries.matrix.test.timeline.FakeMatrixTimeline
 import io.element.android.libraries.matrix.test.timeline.aPollContent
 import io.element.android.libraries.matrix.test.timeline.anEventTimelineItem
 import kotlinx.collections.immutable.persistentListOf
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flowOf
 
-fun aPollTimeline(
+fun aPollTimelineItems(
     polls: Map<EventId, PollContent> = emptyMap(),
-): FakeMatrixTimeline {
-    return FakeMatrixTimeline(
-        initialTimelineItems = polls.map { entry ->
+): Flow<List<MatrixTimelineItem>> {
+    return flowOf(
+        polls.map { entry ->
             MatrixTimelineItem.Event(
                 entry.key.value,
                 anEventTimelineItem(

features/poll/impl/src/test/kotlin/io/element/android/features/poll/impl/create/CreatePollPresenterTest.kt

@@ -25,33 +25,42 @@ import im.vector.app.features.analytics.plan.Composer
 import im.vector.app.features.analytics.plan.PollCreation
 import io.element.android.features.messages.test.FakeMessageComposerContext
 import io.element.android.features.poll.api.create.CreatePollMode
-import io.element.android.features.poll.impl.aPollTimeline
+import io.element.android.features.poll.impl.aPollTimelineItems
 import io.element.android.features.poll.impl.anOngoingPollContent
 import io.element.android.features.poll.impl.data.PollRepository
+import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.poll.PollKind
 import io.element.android.libraries.matrix.api.room.MatrixRoom
 import io.element.android.libraries.matrix.api.timeline.item.event.PollContent
 import io.element.android.libraries.matrix.test.AN_EVENT_ID
 import io.element.android.libraries.matrix.test.room.FakeMatrixRoom
 import io.element.android.libraries.matrix.test.room.SavePollInvocation
+import io.element.android.libraries.matrix.test.timeline.FakeTimeline
+import io.element.android.libraries.matrix.test.timeline.LiveTimelineProvider
 import io.element.android.services.analytics.test.FakeAnalyticsService
 import io.element.android.tests.testutils.WarmUpRule
+import io.element.android.tests.testutils.lambda.assert
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
+import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.test.advanceUntilIdle
 import kotlinx.coroutines.test.runTest
 import org.junit.Rule
 import org.junit.Test
 
-class CreatePollPresenterTest {
+@OptIn(ExperimentalCoroutinesApi::class) class CreatePollPresenterTest {
     @get:Rule
     val warmUpRule = WarmUpRule()
 
     private val pollEventId = AN_EVENT_ID
     private var navUpInvocationsCount = 0
     private val existingPoll = anOngoingPollContent()
+    private val timeline = FakeTimeline(
+        timelineItems = aPollTimelineItems(mapOf(pollEventId to existingPoll))
+    )
     private val fakeMatrixRoom = FakeMatrixRoom(
-        matrixTimeline = aPollTimeline(
-            mapOf(pollEventId to existingPoll)
-        )
+        liveTimeline = timeline
     )
     private val fakeAnalyticsService = FakeAnalyticsService()
     private val fakeMessageComposerContext = FakeMessageComposerContext()
@@ -80,7 +89,7 @@ class CreatePollPresenterTest {
     @Test
     fun `in edit mode, if poll doesn't exist, error is tracked and screen is closed`() = runTest {
         val room = FakeMatrixRoom(
-            matrixTimeline = aPollTimeline()
+            liveTimeline = FakeTimeline()
         )
         val presenter = createCreatePollPresenter(mode = CreatePollMode.EditPoll(AN_EVENT_ID), room = room)
         moleculeFlow(RecompositionMode.Immediate) {
@@ -180,6 +189,12 @@ class CreatePollPresenterTest {
 
     @Test
     fun `edit poll sends a poll edit event`() = runTest {
+        val editPollLambda = lambdaRecorder { _: EventId, _: String, _: List<String>, _: Int, _: PollKind ->
+            Result.success(Unit)
+        }
+        timeline.apply {
+            this.editPollLambda = editPollLambda
+        }
         val presenter = createCreatePollPresenter(mode = CreatePollMode.EditPoll(pollEventId))
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
@@ -201,16 +216,18 @@ class CreatePollPresenterTest {
             ).apply {
                 eventSink(CreatePollEvents.Save)
             }
-            delay(1) // Wait for the coroutine to finish
-            assertThat(fakeMatrixRoom.editPollInvocations.size).isEqualTo(1)
-            assertThat(fakeMatrixRoom.editPollInvocations.last()).isEqualTo(
-                SavePollInvocation(
-                    question = "Changed question",
-                    answers = listOf("Changed answer 1", "Changed answer 2", "Maybe"),
-                    maxSelections = 1,
-                    pollKind = PollKind.Disclosed
+            advanceUntilIdle() // Wait for the coroutine to finish
+
+            assert(editPollLambda)
+                .isCalledOnce()
+                .with(
+                    value(pollEventId),
+                    value("Changed question"),
+                    value(listOf("Changed answer 1", "Changed answer 2", "Maybe")),
+                    value(1),
+                    value(PollKind.Disclosed)
                 )
-            )
+
             assertThat(fakeAnalyticsService.capturedEvents.size).isEqualTo(2)
             assertThat(fakeAnalyticsService.capturedEvents[0]).isEqualTo(
                 Composer(
@@ -233,6 +250,12 @@ class CreatePollPresenterTest {
     @Test
     fun `when edit poll fails, error is tracked`() = runTest {
         val error = Exception("cause")
+        val editPollLambda = lambdaRecorder { _: EventId, _: String, _: List<String>, _: Int, _: PollKind ->
+            Result.failure<Unit>(error)
+        }
+        timeline.apply {
+            this.editPollLambda = editPollLambda
+        }
         fakeMatrixRoom.givenEditPollResult(Result.failure(error))
         val presenter = createCreatePollPresenter(mode = CreatePollMode.EditPoll(pollEventId))
         moleculeFlow(RecompositionMode.Immediate) {
@@ -241,8 +264,8 @@ class CreatePollPresenterTest {
             awaitDefaultItem()
             awaitPollLoaded().eventSink(CreatePollEvents.SetAnswer(0, "A"))
             awaitPollLoaded(newAnswer1 = "A").eventSink(CreatePollEvents.Save)
-            delay(1) // Wait for the coroutine to finish
-            assertThat(fakeMatrixRoom.editPollInvocations).hasSize(1)
+            advanceUntilIdle() // Wait for the coroutine to finish
+            assert(editPollLambda).isCalledOnce()
             assertThat(fakeAnalyticsService.capturedEvents).isEmpty()
             assertThat(fakeAnalyticsService.trackedErrors).hasSize(1)
             assertThat(fakeAnalyticsService.trackedErrors).containsExactly(
@@ -497,22 +520,22 @@ class CreatePollPresenterTest {
         newAnswer1: String? = null,
         newAnswer2: String? = null,
     ) =
-        awaitItem().apply {
-            assertThat(canSave).isTrue()
-            assertThat(canAddAnswer).isTrue()
-            assertThat(question).isEqualTo(newQuestion ?: existingPoll.question)
-            assertThat(answers).isEqualTo(existingPoll.expectedAnswersState().toMutableList().apply {
+        awaitItem().also { state ->
+            assertThat(state.canSave).isTrue()
+            assertThat(state.canAddAnswer).isTrue()
+            assertThat(state.question).isEqualTo(newQuestion ?: existingPoll.question)
+            assertThat(state.answers).isEqualTo(existingPoll.expectedAnswersState().toMutableList().apply {
                 newAnswer1?.let { this[0] = Answer(it, true) }
                 newAnswer2?.let { this[1] = Answer(it, true) }
             })
-            assertThat(pollKind).isEqualTo(existingPoll.kind)
+            assertThat(state.pollKind).isEqualTo(existingPoll.kind)
         }
 
     private fun createCreatePollPresenter(
         mode: CreatePollMode = CreatePollMode.NewPoll,
         room: MatrixRoom = fakeMatrixRoom,
     ): CreatePollPresenter = CreatePollPresenter(
-        repository = PollRepository(room),
+        repository = PollRepository(room, LiveTimelineProvider(room)),
         analyticsService = fakeAnalyticsService,
         messageComposerContext = fakeMessageComposerContext,
         navigateUp = { navUpInvocationsCount++ },

features/poll/impl/src/test/kotlin/io/element/android/features/poll/impl/history/PollHistoryPresenterTest.kt

@@ -22,7 +22,7 @@ import app.cash.turbine.test
 import com.google.common.truth.Truth.assertThat
 import io.element.android.features.poll.api.actions.EndPollAction
 import io.element.android.features.poll.api.actions.SendPollResponseAction
-import io.element.android.features.poll.impl.aPollTimeline
+import io.element.android.features.poll.impl.aPollTimelineItems
 import io.element.android.features.poll.impl.anEndedPollContent
 import io.element.android.features.poll.impl.anOngoingPollContent
 import io.element.android.features.poll.impl.history.model.PollHistoryFilter
@@ -32,14 +32,21 @@ import io.element.android.features.poll.test.actions.FakeEndPollAction
 import io.element.android.features.poll.test.actions.FakeSendPollResponseAction
 import io.element.android.libraries.dateformatter.test.FakeDaySeparatorFormatter
 import io.element.android.libraries.matrix.api.room.MatrixRoom
+import io.element.android.libraries.matrix.api.timeline.Timeline
 import io.element.android.libraries.matrix.test.AN_EVENT_ID
 import io.element.android.libraries.matrix.test.AN_EVENT_ID_2
 import io.element.android.libraries.matrix.test.FakeMatrixClient
 import io.element.android.libraries.matrix.test.room.FakeMatrixRoom
+import io.element.android.libraries.matrix.test.timeline.FakeTimeline
+import io.element.android.libraries.matrix.test.timeline.LiveTimelineProvider
 import io.element.android.tests.testutils.WarmUpRule
+import io.element.android.tests.testutils.lambda.assert
+import io.element.android.tests.testutils.lambda.lambdaRecorder
 import io.element.android.tests.testutils.testCoroutineDispatchers
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.getAndUpdate
 import kotlinx.coroutines.test.TestScope
 import kotlinx.coroutines.test.runCurrent
 import kotlinx.coroutines.test.runTest
@@ -50,14 +57,18 @@ class PollHistoryPresenterTest {
     @get:Rule
     val warmUpRule = WarmUpRule()
 
-    private val timeline = aPollTimeline(
-        polls = mapOf(
-            AN_EVENT_ID to anOngoingPollContent(),
-            AN_EVENT_ID_2 to anEndedPollContent()
-        )
+    private val backwardPaginationStatus = MutableStateFlow(Timeline.PaginationStatus(isPaginating = false, hasMoreToLoad = true))
+    private val timeline = FakeTimeline(
+        timelineItems = aPollTimelineItems(
+            mapOf(
+                AN_EVENT_ID to anOngoingPollContent(),
+                AN_EVENT_ID_2 to anEndedPollContent()
+            )
+        ),
+        backwardPaginationStatus = backwardPaginationStatus
     )
     private val room = FakeMatrixRoom(
-        matrixTimeline = timeline
+        liveTimeline = timeline
     )
 
     @Test
@@ -66,7 +77,6 @@ class PollHistoryPresenterTest {
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            skipItems(1)
             awaitItem().also { state ->
                 assertThat(state.activeFilter).isEqualTo(PollHistoryFilter.ONGOING)
                 assertThat(state.pollHistoryItems.size).isEqualTo(0)
@@ -127,26 +137,30 @@ class PollHistoryPresenterTest {
 
     @Test
     fun `present - load more scenario`() = runTest {
+        val paginateLambda = lambdaRecorder { _: Timeline.PaginationDirection ->
+            Result.success(false)
+        }
+        timeline.apply {
+            this.paginateLambda = paginateLambda
+        }
         val presenter = createPollHistoryPresenter(room = room)
         moleculeFlow(RecompositionMode.Immediate) {
             presenter.present()
         }.test {
-            skipItems(2)
-            awaitItem().also { state ->
-                assertThat(state.pollHistoryItems.size).isEqualTo(2)
-            }
-            timeline.updatePaginationState {
-                copy(isBackPaginating = false)
-            }
+            skipItems(1)
             val loadedState = awaitItem()
             assertThat(loadedState.isLoading).isFalse()
             loadedState.eventSink(PollHistoryEvents.LoadMore)
+            backwardPaginationStatus.getAndUpdate { it.copy(isPaginating = true) }
             awaitItem().also { state ->
                 assertThat(state.isLoading).isTrue()
             }
+            backwardPaginationStatus.getAndUpdate { it.copy(isPaginating = false) }
             awaitItem().also { state ->
                 assertThat(state.isLoading).isFalse()
             }
+            // Called once by the initial load and once by the load more event
+            assert(paginateLambda).isCalledExactly(2)
         }
     }
 
@@ -162,11 +176,11 @@ class PollHistoryPresenterTest {
         ),
     ): PollHistoryPresenter {
         return PollHistoryPresenter(
-            room = room,
             appCoroutineScope = appCoroutineScope,
             sendPollResponseAction = sendPollResponseAction,
             endPollAction = endPollAction,
             pollHistoryItemFactory = pollHistoryItemFactory,
+            timelineProvider = LiveTimelineProvider(room),
         )
     }
 }

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/theme/ColorAliases.kt

@@ -149,6 +149,10 @@ val SemanticColors.bigIconDefaultBackgroundColor
 val SemanticColors.bigCheckmarkBorderColor
     get() = if (isLight) LightColorTokens.colorGray400 else DarkColorTokens.colorGray400
 
+@OptIn(CoreColorToken::class)
+val SemanticColors.highlightedMessageBackgroundColor
+    get() = if (isLight) LightColorTokens.colorGreen300 else DarkColorTokens.colorGreen300
+
 @PreviewsDayNight
 @Composable
 internal fun ColorAliasesPreview() = ElementPreview {
@@ -167,6 +171,8 @@ internal fun ColorAliasesPreview() = ElementPreview {
             "temporaryColorBgSpecial" to ElementTheme.colors.temporaryColorBgSpecial,
             "iconSuccessPrimaryBackground" to ElementTheme.colors.iconSuccessPrimaryBackground,
             "bigIconBackgroundColor" to ElementTheme.colors.bigIconDefaultBackgroundColor,
+            "bigCheckmarkBorderColor" to ElementTheme.colors.bigCheckmarkBorderColor,
+            "highlightedMessageBackgroundColor" to ElementTheme.colors.highlightedMessageBackgroundColor,
         )
     )
 }

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt

@@ -32,8 +32,8 @@ import io.element.android.libraries.matrix.api.poll.PollKind
 import io.element.android.libraries.matrix.api.room.location.AssetType
 import io.element.android.libraries.matrix.api.room.powerlevels.MatrixRoomPowerLevels
 import io.element.android.libraries.matrix.api.room.powerlevels.UserRoleChange
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
 import io.element.android.libraries.matrix.api.timeline.ReceiptType
+import io.element.android.libraries.matrix.api.timeline.Timeline
 import io.element.android.libraries.matrix.api.widget.MatrixWidgetDriver
 import io.element.android.libraries.matrix.api.widget.MatrixWidgetSettings
 import kotlinx.coroutines.flow.Flow
@@ -98,7 +98,16 @@ interface MatrixRoom : Closeable {
 
     val syncUpdateFlow: StateFlow<Long>
 
-    val timeline: MatrixTimeline
+    /**
+     * The live timeline of the room. Must be used to send Event to a room.
+     */
+    val liveTimeline: Timeline
+
+    /**
+     * Create a new timeline, focused on the provided Event.
+     * Should not be used directly, see `TimelineController` to manage the various timelines.
+     */
+    suspend fun timelineFocusedOnEvent(eventId: EventId): Result<Timeline>
 
     fun destroy()
 
@@ -122,12 +131,6 @@ interface MatrixRoom : Closeable {
 
     suspend fun sendMessage(body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit>
 
-    suspend fun editMessage(originalEventId: EventId?, transactionId: TransactionId?, body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit>
-
-    suspend fun enterSpecialMode(eventId: EventId?): Result<Unit>
-
-    suspend fun replyMessage(eventId: EventId, body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit>
-
     suspend fun redactEvent(eventId: EventId, reason: String? = null): Result<Unit>
 
     suspend fun sendImage(

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/errors/FocusEventException.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.api.room.errors
+
+import io.element.android.libraries.matrix.api.core.EventId
+
+sealed class FocusEventException : Exception() {
+    data class InvalidEventId(
+        val eventId: String,
+        val err: String
+    ) : FocusEventException()
+
+    data class EventNotFound(
+        val eventId: EventId
+    ) : FocusEventException()
+
+    data class Other(
+        val msg: String
+    ) : FocusEventException()
+}

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/MatrixTimeline.kt

@@ -1,48 +0,0 @@
-/*
- * Copyright (c) 2023 New Vector Ltd
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.element.android.libraries.matrix.api.timeline
-
-import io.element.android.libraries.matrix.api.core.EventId
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.StateFlow
-
-interface MatrixTimeline : AutoCloseable {
-    data class PaginationState(
-        val isBackPaginating: Boolean,
-        val hasMoreToLoadBackwards: Boolean,
-        val beginningOfRoomReached: Boolean,
-    ) {
-        val canBackPaginate = !isBackPaginating && hasMoreToLoadBackwards
-
-        companion object {
-            val Initial = PaginationState(
-                isBackPaginating = false,
-                hasMoreToLoadBackwards = true,
-                beginningOfRoomReached = false
-            )
-        }
-    }
-
-    val paginationState: StateFlow<PaginationState>
-    val timelineItems: Flow<List<MatrixTimelineItem>>
-    val membershipChangeEventReceived: Flow<Unit>
-
-    suspend fun paginateBackwards(requestSize: Int): Result<Unit>
-    suspend fun paginateBackwards(requestSize: Int, untilNumberOfItems: Int): Result<Unit>
-    suspend fun fetchDetailsForEvent(eventId: EventId): Result<Unit>
-    suspend fun sendReadReceipt(eventId: EventId, receiptType: ReceiptType): Result<Unit>
-}

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/Timeline.kt

@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.api.timeline
+
+import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.ProgressCallback
+import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.libraries.matrix.api.core.TransactionId
+import io.element.android.libraries.matrix.api.media.AudioInfo
+import io.element.android.libraries.matrix.api.media.FileInfo
+import io.element.android.libraries.matrix.api.media.ImageInfo
+import io.element.android.libraries.matrix.api.media.MediaUploadHandler
+import io.element.android.libraries.matrix.api.media.VideoInfo
+import io.element.android.libraries.matrix.api.poll.PollKind
+import io.element.android.libraries.matrix.api.room.Mention
+import io.element.android.libraries.matrix.api.room.location.AssetType
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.StateFlow
+import java.io.File
+
+interface Timeline : AutoCloseable {
+    data class PaginationStatus(
+        val isPaginating: Boolean,
+        val hasMoreToLoad: Boolean,
+    ) {
+        val canPaginate: Boolean = !isPaginating && hasMoreToLoad
+    }
+
+    enum class PaginationDirection {
+        BACKWARDS,
+        FORWARDS
+    }
+
+    val membershipChangeEventReceived: Flow<Unit>
+    suspend fun sendReadReceipt(eventId: EventId, receiptType: ReceiptType): Result<Unit>
+    suspend fun paginate(direction: PaginationDirection): Result<Boolean>
+    fun paginationStatus(direction: PaginationDirection): StateFlow<PaginationStatus>
+    val timelineItems: Flow<List<MatrixTimelineItem>>
+
+    suspend fun sendMessage(body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit>
+
+    suspend fun editMessage(originalEventId: EventId?, transactionId: TransactionId?, body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit>
+
+    suspend fun enterSpecialMode(eventId: EventId?): Result<Unit>
+
+    suspend fun replyMessage(eventId: EventId, body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit>
+
+    suspend fun sendImage(
+        file: File,
+        thumbnailFile: File?,
+        imageInfo: ImageInfo,
+        body: String?,
+        formattedBody: String?,
+        progressCallback: ProgressCallback?
+    ): Result<MediaUploadHandler>
+
+    suspend fun sendVideo(
+        file: File,
+        thumbnailFile: File?,
+        videoInfo: VideoInfo,
+        body: String?,
+        formattedBody: String?,
+        progressCallback: ProgressCallback?
+    ): Result<MediaUploadHandler>
+
+    suspend fun sendAudio(file: File, audioInfo: AudioInfo, progressCallback: ProgressCallback?): Result<MediaUploadHandler>
+
+    suspend fun sendFile(file: File, fileInfo: FileInfo, progressCallback: ProgressCallback?): Result<MediaUploadHandler>
+
+    suspend fun toggleReaction(emoji: String, eventId: EventId): Result<Unit>
+
+    suspend fun forwardEvent(eventId: EventId, roomIds: List<RoomId>): Result<Unit>
+
+    suspend fun retrySendMessage(transactionId: TransactionId): Result<Unit>
+
+    suspend fun cancelSend(transactionId: TransactionId): Result<Unit>
+
+    /**
+     * Share a location message in the room.
+     *
+     * @param body A human readable textual representation of the location.
+     * @param geoUri A geo URI (RFC 5870) representing the location e.g. `geo:51.5008,0.1247;u=35`.
+     *  Respectively: latitude, longitude, and (optional) uncertainty.
+     * @param description Optional description of the location to display to the user.
+     * @param zoomLevel Optional zoom level to display the map at.
+     * @param assetType Optional type of the location asset.
+     *  Set to SENDER if sharing own location. Set to PIN if sharing any location.
+     */
+    suspend fun sendLocation(
+        body: String,
+        geoUri: String,
+        description: String? = null,
+        zoomLevel: Int? = null,
+        assetType: AssetType? = null,
+    ): Result<Unit>
+
+    /**
+     * Create a poll in the room.
+     *
+     * @param question The question to ask.
+     * @param answers The list of answers.
+     * @param maxSelections The maximum number of answers that can be selected.
+     * @param pollKind The kind of poll to create.
+     */
+    suspend fun createPoll(
+        question: String,
+        answers: List<String>,
+        maxSelections: Int,
+        pollKind: PollKind,
+    ): Result<Unit>
+
+    /**
+     * Edit a poll in the room.
+     *
+     * @param pollStartId The event ID of the poll start event.
+     * @param question The question to ask.
+     * @param answers The list of answers.
+     * @param maxSelections The maximum number of answers that can be selected.
+     * @param pollKind The kind of poll to create.
+     */
+    suspend fun editPoll(
+        pollStartId: EventId,
+        question: String,
+        answers: List<String>,
+        maxSelections: Int,
+        pollKind: PollKind,
+    ): Result<Unit>
+
+    /**
+     * Send a response to a poll.
+     *
+     * @param pollStartId The event ID of the poll start event.
+     * @param answers The list of answer ids to send.
+     */
+    suspend fun sendPollResponse(pollStartId: EventId, answers: List<String>): Result<Unit>
+
+    /**
+     * Ends a poll in the room.
+     *
+     * @param pollStartId The event ID of the poll start event.
+     * @param text Fallback text of the poll end event.
+     */
+    suspend fun endPoll(pollStartId: EventId, text: String): Result<Unit>
+
+    suspend fun sendVoiceMessage(
+        file: File,
+        audioInfo: AudioInfo,
+        waveform: List<Float>,
+        progressCallback: ProgressCallback?
+    ): Result<MediaUploadHandler>
+}

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/TimelineProvider.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.api.timeline
+
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.first
+
+/**
+ * This interface defines a way to get the active timeline.
+ * It could be the current room timeline, or a timeline for a specific event.
+ */
+interface TimelineProvider {
+    fun activeTimelineFlow(): StateFlow<Timeline>
+}
+
+suspend fun TimelineProvider.getActiveTimeline(): Timeline = activeTimelineFlow().first()

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/InReplyTo.kt

@@ -26,7 +26,7 @@ sealed interface InReplyTo {
     data class NotLoaded(val eventId: EventId) : InReplyTo
 
     /** The event details are pending to be fetched. We should **not** fetch them again. */
-    data object Pending : InReplyTo
+    data class Pending(val eventId: EventId) : InReplyTo
 
     /** The event details are available. */
     data class Ready(
@@ -44,5 +44,8 @@ sealed interface InReplyTo {
      * If the reason for the failure is consistent on the server, we'd enter a loop
      * where we keep trying to fetch the same event.
      * */
-    data object Error : InReplyTo
+    data class Error(
+        val eventId: EventId,
+        val message: String,
+    ) : InReplyTo
 }

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/virtual/VirtualTimelineItem.kt

@@ -16,6 +16,8 @@
 
 package io.element.android.libraries.matrix.api.timeline.item.virtual
 
+import io.element.android.libraries.matrix.api.timeline.Timeline
+
 sealed interface VirtualTimelineItem {
     data class DayDivider(
         val timestamp: Long
@@ -24,4 +26,13 @@ sealed interface VirtualTimelineItem {
     data object ReadMarker : VirtualTimelineItem
 
     data object EncryptedHistoryBanner : VirtualTimelineItem
+
+    data object RoomBeginning : VirtualTimelineItem
+
+    data object LastForwardIndicator : VirtualTimelineItem
+
+    data class LoadingIndicator(
+        val direction: Timeline.PaginationDirection,
+        val timestamp: Long,
+    ) : VirtualTimelineItem
 }

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/room/FocusEventException.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.room
+
+import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.room.errors.FocusEventException
+import org.matrix.rustcomponents.sdk.FocusEventException as RustFocusEventException
+
+fun Throwable.toFocusEventException(): Throwable {
+    return when (this) {
+        is RustFocusEventException -> {
+            when (this) {
+                is RustFocusEventException.InvalidEventId -> {
+                    FocusEventException.InvalidEventId(eventId, err)
+                }
+                is RustFocusEventException.EventNotFound -> {
+                    FocusEventException.EventNotFound(EventId(eventId))
+                }
+                is RustFocusEventException.Other -> {
+                    FocusEventException.Other(msg)
+                }
+            }
+        }
+        else -> {
+            this
+        }
+    }
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/room/RustMatrixRoom.kt

@@ -18,6 +18,7 @@ package io.element.android.libraries.matrix.impl.room
 
 import io.element.android.libraries.core.coroutine.CoroutineDispatchers
 import io.element.android.libraries.core.coroutine.childScope
+import io.element.android.libraries.core.extensions.mapFailure
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.ProgressCallback
 import io.element.android.libraries.matrix.api.core.RoomAlias
@@ -43,21 +44,15 @@ import io.element.android.libraries.matrix.api.room.location.AssetType
 import io.element.android.libraries.matrix.api.room.powerlevels.MatrixRoomPowerLevels
 import io.element.android.libraries.matrix.api.room.powerlevels.UserRoleChange
 import io.element.android.libraries.matrix.api.room.roomNotificationSettings
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
 import io.element.android.libraries.matrix.api.timeline.ReceiptType
+import io.element.android.libraries.matrix.api.timeline.Timeline
 import io.element.android.libraries.matrix.api.widget.MatrixWidgetDriver
 import io.element.android.libraries.matrix.api.widget.MatrixWidgetSettings
-import io.element.android.libraries.matrix.impl.core.toProgressWatcher
-import io.element.android.libraries.matrix.impl.media.MediaUploadHandlerImpl
-import io.element.android.libraries.matrix.impl.media.map
-import io.element.android.libraries.matrix.impl.media.toMSC3246range
 import io.element.android.libraries.matrix.impl.notificationsettings.RustNotificationSettingsService
-import io.element.android.libraries.matrix.impl.poll.toInner
-import io.element.android.libraries.matrix.impl.room.location.toInner
 import io.element.android.libraries.matrix.impl.room.member.RoomMemberListFetcher
 import io.element.android.libraries.matrix.impl.room.member.RoomMemberMapper
 import io.element.android.libraries.matrix.impl.room.powerlevels.RoomPowerLevelsMapper
-import io.element.android.libraries.matrix.impl.timeline.RustMatrixTimeline
+import io.element.android.libraries.matrix.impl.timeline.RustTimeline
 import io.element.android.libraries.matrix.impl.timeline.toRustReceiptType
 import io.element.android.libraries.matrix.impl.util.mxCallbackFlow
 import io.element.android.libraries.matrix.impl.widget.RustWidgetDriver
@@ -80,24 +75,16 @@ import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
-import org.matrix.rustcomponents.sdk.EventTimelineItem
-import org.matrix.rustcomponents.sdk.MessageFormat
 import org.matrix.rustcomponents.sdk.RoomInfo
 import org.matrix.rustcomponents.sdk.RoomInfoListener
 import org.matrix.rustcomponents.sdk.RoomListItem
-import org.matrix.rustcomponents.sdk.RoomMessageEventContentWithoutRelation
-import org.matrix.rustcomponents.sdk.SendAttachmentJoinHandle
 import org.matrix.rustcomponents.sdk.TypingNotificationsListener
 import org.matrix.rustcomponents.sdk.UserPowerLevelUpdate
 import org.matrix.rustcomponents.sdk.WidgetCapabilities
 import org.matrix.rustcomponents.sdk.WidgetCapabilitiesProvider
-import org.matrix.rustcomponents.sdk.messageEventContentFromHtml
-import org.matrix.rustcomponents.sdk.messageEventContentFromMarkdown
 import org.matrix.rustcomponents.sdk.use
-import timber.log.Timber
 import uniffi.matrix_sdk.RoomPowerLevelChanges
 import java.io.File
-import org.matrix.rustcomponents.sdk.FormattedBody as RustFormattedBody
 import org.matrix.rustcomponents.sdk.Room as InnerRoom
 import org.matrix.rustcomponents.sdk.Timeline as InnerTimeline
 
@@ -107,7 +94,7 @@ class RustMatrixRoom(
     private val isKeyBackupEnabled: Boolean,
     private val roomListItem: RoomListItem,
     private val innerRoom: InnerRoom,
-    private val innerTimeline: InnerTimeline,
+    innerTimeline: InnerTimeline,
     private val roomNotificationSettingsService: RustNotificationSettingsService,
     sessionCoroutineScope: CoroutineScope,
     private val coroutineDispatchers: CoroutineDispatchers,
@@ -160,7 +147,7 @@ class RustMatrixRoom(
     private val _roomNotificationSettingsStateFlow = MutableStateFlow<MatrixRoomNotificationSettingsState>(MatrixRoomNotificationSettingsState.Unknown)
     override val roomNotificationSettingsStateFlow: StateFlow<MatrixRoomNotificationSettingsState> = _roomNotificationSettingsStateFlow
 
-    override val timeline = createMatrixTimeline(innerTimeline) {
+    override val liveTimeline = createTimeline(innerTimeline, isLive = true) {
         _syncUpdateFlow.value = systemClock.epochMillis()
     }
 
@@ -170,7 +157,7 @@ class RustMatrixRoom(
 
     init {
         val powerLevelChanges = roomInfoFlow.map { it.userPowerLevels }.distinctUntilChanged()
-        val membershipChanges = timeline.membershipChangeEventReceived.onStart { emit(Unit) }
+        val membershipChanges = liveTimeline.membershipChangeEventReceived.onStart { emit(Unit) }
         combine(membershipChanges, powerLevelChanges) { _, _ -> }
             // Skip initial one
             .drop(1)
@@ -183,12 +170,25 @@ class RustMatrixRoom(
 
     override suspend fun unsubscribeFromSync() = roomSyncSubscriber.unsubscribe(roomId)
 
+    override suspend fun timelineFocusedOnEvent(eventId: EventId): Result<Timeline> {
+        return runCatching {
+            innerRoom.timelineFocusedOnEvent(
+                eventId = eventId.value,
+                numContextEvents = 50u,
+                internalIdPrefix = "focus_$eventId",
+            ).let { inner ->
+                createTimeline(inner, isLive = false)
+            }
+        }.mapFailure {
+            it.toFocusEventException()
+        }
+    }
+
     override fun destroy() {
         roomCoroutineScope.cancel()
-        timeline.close()
+        liveTimeline.close()
         innerRoom.destroy()
         roomListItem.destroy()
-        specialModeEventTimelineItem?.destroy()
     }
 
     override val name: String?
@@ -322,59 +322,8 @@ class RustMatrixRoom(
         }
     }
 
-    override suspend fun sendMessage(body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit> = withContext(roomDispatcher) {
-        messageEventContentFromParts(body, htmlBody).withMentions(mentions.map()).use { content ->
-            runCatching {
-                innerTimeline.send(content)
-            }
-        }
-    }
-
-    override suspend fun editMessage(
-        originalEventId: EventId?,
-        transactionId: TransactionId?,
-        body: String,
-        htmlBody: String?,
-        mentions: List<Mention>,
-    ): Result<Unit> =
-        withContext(roomDispatcher) {
-            if (originalEventId != null) {
-                runCatching {
-                    val editedEvent = specialModeEventTimelineItem ?: innerTimeline.getEventTimelineItemByEventId(originalEventId.value)
-                    editedEvent.use {
-                        innerTimeline.edit(
-                            newContent = messageEventContentFromParts(body, htmlBody).withMentions(mentions.map()),
-                            editItem = it,
-                        )
-                    }
-                    specialModeEventTimelineItem = null
-                }
-            } else {
-                runCatching {
-                    transactionId?.let { cancelSend(it) }
-                    innerTimeline.send(messageEventContentFromParts(body, htmlBody))
-                }
-            }
-        }
-
-    private var specialModeEventTimelineItem: EventTimelineItem? = null
-
-    override suspend fun enterSpecialMode(eventId: EventId?): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            specialModeEventTimelineItem?.destroy()
-            specialModeEventTimelineItem = null
-            specialModeEventTimelineItem = eventId?.let { innerTimeline.getEventTimelineItemByEventId(it.value) }
-        }
-    }
-
-    override suspend fun replyMessage(eventId: EventId, body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            val inReplyTo = specialModeEventTimelineItem ?: innerTimeline.getEventTimelineItemByEventId(eventId.value)
-            inReplyTo.use { eventTimelineItem ->
-                innerTimeline.sendReply(messageEventContentFromParts(body, htmlBody).withMentions(mentions.map()), eventTimelineItem)
-            }
-            specialModeEventTimelineItem = null
-        }
+    override suspend fun sendMessage(body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit> {
+        return liveTimeline.sendMessage(body, htmlBody, mentions)
     }
 
     override suspend fun redactEvent(eventId: EventId, reason: String?) = withContext(roomDispatcher) {
@@ -457,18 +406,7 @@ class RustMatrixRoom(
         formattedBody: String?,
         progressCallback: ProgressCallback?,
     ): Result<MediaUploadHandler> {
-        return sendAttachment(listOfNotNull(file, thumbnailFile)) {
-            innerTimeline.sendImage(
-                url = file.path,
-                thumbnailUrl = thumbnailFile?.path,
-                imageInfo = imageInfo.map(),
-                caption = body,
-                formattedCaption = formattedBody?.let {
-                    RustFormattedBody(body = it, format = MessageFormat.Html)
-                },
-                progressWatcher = progressCallback?.toProgressWatcher()
-            )
-        }
+        return liveTimeline.sendImage(file, thumbnailFile, imageInfo, body, formattedBody, progressCallback)
     }
 
     override suspend fun sendVideo(
@@ -479,63 +417,31 @@ class RustMatrixRoom(
         formattedBody: String?,
         progressCallback: ProgressCallback?,
     ): Result<MediaUploadHandler> {
-        return sendAttachment(listOfNotNull(file, thumbnailFile)) {
-            innerTimeline.sendVideo(
-                url = file.path,
-                thumbnailUrl = thumbnailFile?.path,
-                videoInfo = videoInfo.map(),
-                caption = body,
-                formattedCaption = formattedBody?.let {
-                    RustFormattedBody(body = it, format = MessageFormat.Html)
-                },
-                progressWatcher = progressCallback?.toProgressWatcher()
-            )
-        }
+        return liveTimeline.sendVideo(file, thumbnailFile, videoInfo, body, formattedBody, progressCallback)
     }
 
     override suspend fun sendAudio(file: File, audioInfo: AudioInfo, progressCallback: ProgressCallback?): Result<MediaUploadHandler> {
-        return sendAttachment(listOf(file)) {
-            innerTimeline.sendAudio(
-                url = file.path,
-                audioInfo = audioInfo.map(),
-                // Maybe allow a caption in the future?
-                caption = null,
-                formattedCaption = null,
-                progressWatcher = progressCallback?.toProgressWatcher()
-            )
-        }
+        return liveTimeline.sendAudio(file, audioInfo, progressCallback)
     }
 
     override suspend fun sendFile(file: File, fileInfo: FileInfo, progressCallback: ProgressCallback?): Result<MediaUploadHandler> {
-        return sendAttachment(listOf(file)) {
-            innerTimeline.sendFile(file.path, fileInfo.map(), progressCallback?.toProgressWatcher())
-        }
+        return liveTimeline.sendFile(file, fileInfo, progressCallback)
     }
 
-    override suspend fun toggleReaction(emoji: String, eventId: EventId): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            innerTimeline.toggleReaction(key = emoji, eventId = eventId.value)
-        }
+    override suspend fun toggleReaction(emoji: String, eventId: EventId): Result<Unit> {
+        return liveTimeline.toggleReaction(emoji, eventId)
     }
 
-    override suspend fun forwardEvent(eventId: EventId, roomIds: List<RoomId>): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            roomContentForwarder.forward(fromTimeline = innerTimeline, eventId = eventId, toRoomIds = roomIds)
-        }.onFailure {
-            Timber.e(it)
-        }
+    override suspend fun forwardEvent(eventId: EventId, roomIds: List<RoomId>): Result<Unit> {
+        return liveTimeline.forwardEvent(eventId, roomIds)
     }
 
-    override suspend fun retrySendMessage(transactionId: TransactionId): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            innerTimeline.retrySend(transactionId.value)
-        }
+    override suspend fun retrySendMessage(transactionId: TransactionId): Result<Unit> {
+        return liveTimeline.retrySendMessage(transactionId)
     }
 
-    override suspend fun cancelSend(transactionId: TransactionId): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            innerTimeline.cancelSend(transactionId.value)
-        }
+    override suspend fun cancelSend(transactionId: TransactionId): Result<Unit> {
+        return liveTimeline.cancelSend(transactionId)
     }
 
     override suspend fun updateAvatar(mimeType: String, data: ByteArray): Result<Unit> = withContext(roomDispatcher) {
@@ -613,16 +519,8 @@ class RustMatrixRoom(
         description: String?,
         zoomLevel: Int?,
         assetType: AssetType?,
-    ): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            innerTimeline.sendLocation(
-                body = body,
-                geoUri = geoUri,
-                description = description,
-                zoomLevel = zoomLevel?.toUByte(),
-                assetType = assetType?.toInner(),
-            )
-        }
+    ): Result<Unit> {
+        return liveTimeline.sendLocation(body, geoUri, description, zoomLevel, assetType)
     }
 
     override suspend fun createPoll(
@@ -630,15 +528,8 @@ class RustMatrixRoom(
         answers: List<String>,
         maxSelections: Int,
         pollKind: PollKind,
-    ): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            innerTimeline.createPoll(
-                question = question,
-                answers = answers,
-                maxSelections = maxSelections.toUByte(),
-                pollKind = pollKind.toInner(),
-            )
-        }
+    ): Result<Unit> {
+        return liveTimeline.createPoll(question, answers, maxSelections, pollKind)
     }
 
     override suspend fun editPoll(
@@ -647,46 +538,22 @@ class RustMatrixRoom(
         answers: List<String>,
         maxSelections: Int,
         pollKind: PollKind,
-    ): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            val pollStartEvent =
-                innerTimeline.getEventTimelineItemByEventId(
-                    eventId = pollStartId.value
-                )
-            pollStartEvent.use {
-                innerTimeline.editPoll(
-                    question = question,
-                    answers = answers,
-                    maxSelections = maxSelections.toUByte(),
-                    pollKind = pollKind.toInner(),
-                    editItem = pollStartEvent,
-                )
-            }
-        }
+    ): Result<Unit> {
+        return liveTimeline.editPoll(pollStartId, question, answers, maxSelections, pollKind)
     }
 
     override suspend fun sendPollResponse(
         pollStartId: EventId,
         answers: List<String>
-    ): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            innerTimeline.sendPollResponse(
-                pollStartId = pollStartId.value,
-                answers = answers,
-            )
-        }
+    ): Result<Unit> {
+        return liveTimeline.sendPollResponse(pollStartId, answers)
     }
 
     override suspend fun endPoll(
         pollStartId: EventId,
         text: String
-    ): Result<Unit> = withContext(roomDispatcher) {
-        runCatching {
-            innerTimeline.endPoll(
-                pollStartId = pollStartId.value,
-                text = text,
-            )
-        }
+    ): Result<Unit> {
+        return liveTimeline.endPoll(pollStartId, text)
     }
 
     override suspend fun sendVoiceMessage(
@@ -694,16 +561,8 @@ class RustMatrixRoom(
         audioInfo: AudioInfo,
         waveform: List<Float>,
         progressCallback: ProgressCallback?,
-    ): Result<MediaUploadHandler> = sendAttachment(listOf(file)) {
-        innerTimeline.sendVoiceMessage(
-            url = file.path,
-            audioInfo = audioInfo.map(),
-            waveform = waveform.toMSC3246range(),
-            // Maybe allow a caption in the future?
-            caption = null,
-            formattedCaption = null,
-            progressWatcher = progressCallback?.toProgressWatcher(),
-        )
+    ): Result<MediaUploadHandler> {
+        return liveTimeline.sendVoiceMessage(file, audioInfo, waveform, progressCallback)
     }
 
     override suspend fun typingNotice(isTyping: Boolean) = runCatching {
@@ -739,31 +598,22 @@ class RustMatrixRoom(
         innerRoom.matrixToEventPermalink(eventId.value)
     }
 
-    private fun sendAttachment(files: List<File>, handle: () -> SendAttachmentJoinHandle): Result<MediaUploadHandler> {
-        return runCatching {
-            MediaUploadHandlerImpl(files, handle())
-        }
-    }
-
-    private fun createMatrixTimeline(
+    private fun createTimeline(
         timeline: InnerTimeline,
+        isLive: Boolean,
         onNewSyncedEvent: () -> Unit = {},
-    ): MatrixTimeline {
-        return RustMatrixTimeline(
+    ): Timeline {
+        return RustTimeline(
             isKeyBackupEnabled = isKeyBackupEnabled,
+            isLive = isLive,
             matrixRoom = this,
+            systemClock = systemClock,
             roomCoroutineScope = roomCoroutineScope,
             dispatcher = roomDispatcher,
             lastLoginTimestamp = sessionData.loginTimestamp,
             onNewSyncedEvent = onNewSyncedEvent,
-            innerTimeline = timeline,
+            roomContentForwarder = roomContentForwarder,
+            inner = timeline,
         )
     }
-
-    private fun messageEventContentFromParts(body: String, htmlBody: String?): RoomMessageEventContentWithoutRelation =
-        if (htmlBody != null) {
-            messageEventContentFromHtml(body, htmlBody)
-        } else {
-            messageEventContentFromMarkdown(body)
-        }
 }

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/AsyncMatrixTimeline.kt

@@ -1,106 +0,0 @@
-/*
- * Copyright (c) 2023 New Vector Ltd
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.element.android.libraries.matrix.impl.timeline
-
-import io.element.android.libraries.matrix.api.core.EventId
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
-import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
-import io.element.android.libraries.matrix.api.timeline.ReceiptType
-import kotlinx.coroutines.CompletableDeferred
-import kotlinx.coroutines.CoroutineDispatcher
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.CoroutineStart
-import kotlinx.coroutines.NonCancellable
-import kotlinx.coroutines.async
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.MutableSharedFlow
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.launchIn
-import kotlinx.coroutines.flow.onEach
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
-import timber.log.Timber
-
-/**
- * This class is a wrapper around a [MatrixTimeline] that will be created asynchronously.
- */
-@Suppress("unused")
-class AsyncMatrixTimeline(
-    coroutineScope: CoroutineScope,
-    dispatcher: CoroutineDispatcher,
-    private val timelineProvider: suspend () -> MatrixTimeline
-) : MatrixTimeline {
-    private val _timelineItems: MutableStateFlow<List<MatrixTimelineItem>> =
-        MutableStateFlow(emptyList())
-
-    private val _paginationState = MutableStateFlow(
-        MatrixTimeline.PaginationState.Initial
-    )
-    private val timeline = coroutineScope.async(context = dispatcher, start = CoroutineStart.LAZY) {
-        timelineProvider()
-    }
-    private val closeSignal = CompletableDeferred<Unit>()
-
-    override val membershipChangeEventReceived = MutableSharedFlow<Unit>(extraBufferCapacity = 1)
-
-    init {
-        coroutineScope.launch {
-            val delegateTimeline = timeline.await()
-            delegateTimeline.timelineItems
-                .onEach { _timelineItems.value = it }
-                .launchIn(this)
-            delegateTimeline.paginationState
-                .onEach { _paginationState.value = it }
-                .launchIn(this)
-            delegateTimeline.membershipChangeEventReceived
-                .onEach { membershipChangeEventReceived.emit(it) }
-                .launchIn(this)
-
-            launch {
-                withContext(NonCancellable) {
-                    closeSignal.await()
-                    Timber.d("Close delegate")
-                    delegateTimeline.close()
-                }
-            }
-        }
-    }
-
-    override val paginationState: StateFlow<MatrixTimeline.PaginationState> = _paginationState
-    override val timelineItems: Flow<List<MatrixTimelineItem>> = _timelineItems
-
-    override suspend fun paginateBackwards(requestSize: Int): Result<Unit> {
-        return timeline.await().paginateBackwards(requestSize)
-    }
-
-    override suspend fun paginateBackwards(requestSize: Int, untilNumberOfItems: Int): Result<Unit> {
-        return timeline.await().paginateBackwards(requestSize, untilNumberOfItems)
-    }
-
-    override suspend fun fetchDetailsForEvent(eventId: EventId): Result<Unit> {
-        return timeline.await().fetchDetailsForEvent(eventId)
-    }
-
-    override suspend fun sendReadReceipt(eventId: EventId, receiptType: ReceiptType): Result<Unit> {
-        return timeline.await().sendReadReceipt(eventId, receiptType)
-    }
-
-    override fun close() {
-        closeSignal.complete(Unit)
-    }
-}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/RoomTimelineExtensions.kt

@@ -16,10 +16,8 @@
 
 package io.element.android.libraries.matrix.impl.timeline
 
-import io.element.android.libraries.core.data.tryOrNull
 import io.element.android.libraries.matrix.impl.util.cancelAndDestroy
 import io.element.android.libraries.matrix.impl.util.destroyAll
-import io.element.android.libraries.matrix.impl.util.mxCallbackFlow
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.channels.trySendBlocking
@@ -27,13 +25,11 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.buffer
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.catch
-import org.matrix.rustcomponents.sdk.PaginationStatusListener
 import org.matrix.rustcomponents.sdk.Timeline
 import org.matrix.rustcomponents.sdk.TimelineDiff
 import org.matrix.rustcomponents.sdk.TimelineItem
 import org.matrix.rustcomponents.sdk.TimelineListener
 import timber.log.Timber
-import uniffi.matrix_sdk_ui.PaginationStatus
 
 internal fun Timeline.timelineDiffFlow(onInitialList: suspend (List<TimelineItem>) -> Unit): Flow<List<TimelineDiff>> =
     callbackFlow {
@@ -58,18 +54,6 @@ internal fun Timeline.timelineDiffFlow(onInitialList: suspend (List<TimelineItem
         Timber.d(it, "timelineDiffFlow() failed")
     }.buffer(Channel.UNLIMITED)
 
-internal fun Timeline.backPaginationStatusFlow(): Flow<PaginationStatus> =
-    mxCallbackFlow {
-        val listener = object : PaginationStatusListener {
-            override fun onUpdate(status: PaginationStatus) {
-                trySendBlocking(status)
-            }
-        }
-        tryOrNull {
-            subscribeToBackPaginationStatus(listener)
-        }
-    }.buffer(Channel.UNLIMITED)
-
 internal suspend fun Timeline.runWithTimelineListenerRegistered(action: suspend () -> Unit) {
     val result = addListener(NoOpTimelineListener)
     try {

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/RustMatrixTimeline.kt

@@ -1,278 +0,0 @@
-/*
- * Copyright (c) 2023 New Vector Ltd
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.element.android.libraries.matrix.impl.timeline
-
-import io.element.android.libraries.matrix.api.core.EventId
-import io.element.android.libraries.matrix.api.room.MatrixRoom
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
-import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
-import io.element.android.libraries.matrix.api.timeline.ReceiptType
-import io.element.android.libraries.matrix.api.timeline.TimelineException
-import io.element.android.libraries.matrix.api.timeline.item.virtual.VirtualTimelineItem
-import io.element.android.libraries.matrix.impl.timeline.item.event.EventMessageMapper
-import io.element.android.libraries.matrix.impl.timeline.item.event.EventTimelineItemMapper
-import io.element.android.libraries.matrix.impl.timeline.item.event.TimelineEventContentMapper
-import io.element.android.libraries.matrix.impl.timeline.item.virtual.VirtualTimelineItemMapper
-import io.element.android.libraries.matrix.impl.timeline.postprocessor.DmBeginningTimelineProcessor
-import io.element.android.libraries.matrix.impl.timeline.postprocessor.TimelineEncryptedHistoryPostProcessor
-import kotlinx.coroutines.CompletableDeferred
-import kotlinx.coroutines.CoroutineDispatcher
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.coroutineScope
-import kotlinx.coroutines.ensureActive
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.asStateFlow
-import kotlinx.coroutines.flow.combine
-import kotlinx.coroutines.flow.launchIn
-import kotlinx.coroutines.flow.mapLatest
-import kotlinx.coroutines.flow.onEach
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
-import org.matrix.rustcomponents.sdk.PaginationOptions
-import org.matrix.rustcomponents.sdk.Timeline
-import org.matrix.rustcomponents.sdk.TimelineDiff
-import org.matrix.rustcomponents.sdk.TimelineItem
-import timber.log.Timber
-import uniffi.matrix_sdk_ui.EventItemOrigin
-import uniffi.matrix_sdk_ui.PaginationStatus
-import java.util.Date
-import java.util.concurrent.atomic.AtomicBoolean
-
-private const val INITIAL_MAX_SIZE = 50
-
-class RustMatrixTimeline(
-    roomCoroutineScope: CoroutineScope,
-    isKeyBackupEnabled: Boolean,
-    private val matrixRoom: MatrixRoom,
-    private val innerTimeline: Timeline,
-    private val dispatcher: CoroutineDispatcher,
-    lastLoginTimestamp: Date?,
-    private val onNewSyncedEvent: () -> Unit,
-) : MatrixTimeline {
-    private val initLatch = CompletableDeferred<Unit>()
-    private val isInit = AtomicBoolean(false)
-
-    private val _timelineItems: MutableStateFlow<List<MatrixTimelineItem>> =
-        MutableStateFlow(emptyList())
-
-    private val _paginationState = MutableStateFlow(
-        MatrixTimeline.PaginationState.Initial
-    )
-
-    private val encryptedHistoryPostProcessor = TimelineEncryptedHistoryPostProcessor(
-        lastLoginTimestamp = lastLoginTimestamp,
-        isRoomEncrypted = matrixRoom.isEncrypted,
-        isKeyBackupEnabled = isKeyBackupEnabled,
-        dispatcher = dispatcher,
-    )
-
-    private val dmBeginningTimelineProcessor = DmBeginningTimelineProcessor()
-
-    private val timelineItemFactory = MatrixTimelineItemMapper(
-        fetchDetailsForEvent = this::fetchDetailsForEvent,
-        roomCoroutineScope = roomCoroutineScope,
-        virtualTimelineItemMapper = VirtualTimelineItemMapper(),
-        eventTimelineItemMapper = EventTimelineItemMapper(
-            contentMapper = TimelineEventContentMapper(
-                eventMessageMapper = EventMessageMapper()
-            )
-        )
-    )
-
-    private val timelineDiffProcessor = MatrixTimelineDiffProcessor(
-        timelineItems = _timelineItems,
-        timelineItemFactory = timelineItemFactory,
-    )
-
-    override val paginationState: StateFlow<MatrixTimeline.PaginationState> = _paginationState.asStateFlow()
-
-    @OptIn(ExperimentalCoroutinesApi::class)
-    override val timelineItems: Flow<List<MatrixTimelineItem>> = _timelineItems
-        .mapLatest { items -> encryptedHistoryPostProcessor.process(items) }
-        .mapLatest { items ->
-            dmBeginningTimelineProcessor.process(
-                items = items,
-                isDm = matrixRoom.isDirect && matrixRoom.isOneToOne,
-                isAtStartOfTimeline = paginationState.value.beginningOfRoomReached
-            )
-        }
-
-    override val membershipChangeEventReceived: Flow<Unit> = timelineDiffProcessor.membershipChangeEventReceived
-
-    init {
-        Timber.d("Initialize timeline for room ${matrixRoom.roomId}")
-
-        roomCoroutineScope.launch(dispatcher) {
-            innerTimeline.timelineDiffFlow { initialList ->
-                postItems(initialList)
-            }.onEach { diffs ->
-                if (diffs.any { diff -> diff.eventOrigin() == EventItemOrigin.SYNC }) {
-                    onNewSyncedEvent()
-                }
-                postDiffs(diffs)
-            }.launchIn(this)
-
-            paginationStateFlow()
-                .onEach {
-                    _paginationState.value = it
-                }
-                .launchIn(this)
-
-            fetchMembers()
-        }
-    }
-
-    private fun paginationStateFlow(): Flow<MatrixTimeline.PaginationState> {
-        return combine(
-            innerTimeline.backPaginationStatusFlow(),
-            timelineItems,
-        ) { paginationStatus, filteredItems ->
-            if (filteredItems.hasEncryptionHistoryBanner()) {
-                return@combine MatrixTimeline.PaginationState(
-                    isBackPaginating = false,
-                    hasMoreToLoadBackwards = false,
-                    beginningOfRoomReached = false,
-                )
-            }
-            when (paginationStatus) {
-                PaginationStatus.IDLE -> {
-                    MatrixTimeline.PaginationState(
-                        isBackPaginating = false,
-                        hasMoreToLoadBackwards = true,
-                        beginningOfRoomReached = false,
-                    )
-                }
-                PaginationStatus.PAGINATING -> {
-                    MatrixTimeline.PaginationState(
-                        isBackPaginating = true,
-                        hasMoreToLoadBackwards = true,
-                        beginningOfRoomReached = false,
-                    )
-                }
-                PaginationStatus.TIMELINE_END_REACHED -> {
-                    MatrixTimeline.PaginationState(
-                        isBackPaginating = false,
-                        hasMoreToLoadBackwards = false,
-                        beginningOfRoomReached = true,
-                    )
-                }
-            }
-        }
-    }
-
-    private suspend fun fetchMembers() = withContext(dispatcher) {
-        initLatch.await()
-        try {
-            innerTimeline.fetchMembers()
-        } catch (exception: Exception) {
-            Timber.e(exception, "Error fetching members for room ${matrixRoom.roomId}")
-        }
-    }
-
-    private suspend fun postItems(items: List<TimelineItem>) = coroutineScope {
-        // Split the initial items in multiple list as there is no pagination in the cached data, so we can post timelineItems asap.
-        items.chunked(INITIAL_MAX_SIZE).reversed().forEach {
-            ensureActive()
-            timelineDiffProcessor.postItems(it)
-        }
-        isInit.set(true)
-        initLatch.complete(Unit)
-    }
-
-    private suspend fun postDiffs(diffs: List<TimelineDiff>) {
-        initLatch.await()
-        timelineDiffProcessor.postDiffs(diffs)
-    }
-
-    override suspend fun fetchDetailsForEvent(eventId: EventId): Result<Unit> = withContext(dispatcher) {
-        runCatching {
-            innerTimeline.fetchDetailsForEvent(eventId.value)
-        }
-    }
-
-    override suspend fun paginateBackwards(requestSize: Int): Result<Unit> {
-        val paginationOptions = PaginationOptions.SimpleRequest(
-            eventLimit = requestSize.toUShort(),
-            waitForToken = true,
-        )
-        return paginateBackwards(paginationOptions)
-    }
-
-    override suspend fun paginateBackwards(requestSize: Int, untilNumberOfItems: Int): Result<Unit> {
-        val paginationOptions = PaginationOptions.UntilNumItems(
-            eventLimit = requestSize.toUShort(),
-            items = untilNumberOfItems.toUShort(),
-            waitForToken = true,
-        )
-        return paginateBackwards(paginationOptions)
-    }
-
-    private suspend fun paginateBackwards(paginationOptions: PaginationOptions): Result<Unit> = withContext(dispatcher) {
-        initLatch.await()
-        runCatching {
-            if (!canBackPaginate()) throw TimelineException.CannotPaginate
-            Timber.v("Start back paginating for room ${matrixRoom.roomId} ")
-            innerTimeline.paginateBackwards(
-                when (paginationOptions) {
-                    is PaginationOptions.SimpleRequest -> paginationOptions.eventLimit
-                    is PaginationOptions.UntilNumItems -> paginationOptions.eventLimit
-                }
-            )
-        }.onFailure { error ->
-            if (error is TimelineException.CannotPaginate) {
-                Timber.d("Can't paginate backwards on room ${matrixRoom.roomId}, we're already at the start")
-            } else {
-                Timber.e(error, "Error paginating backwards on room ${matrixRoom.roomId}")
-            }
-        }.onSuccess {
-            Timber.v("Success back paginating for room ${matrixRoom.roomId}")
-        }.map { }
-    }
-
-    private fun canBackPaginate(): Boolean {
-        return isInit.get() && paginationState.value.canBackPaginate
-    }
-
-    override suspend fun sendReadReceipt(
-        eventId: EventId,
-        receiptType: ReceiptType,
-    ) = withContext(dispatcher) {
-        runCatching {
-            innerTimeline.sendReadReceipt(
-                receiptType = receiptType.toRustReceiptType(),
-                eventId = eventId.value,
-            )
-        }
-    }
-
-    override fun close() {
-        innerTimeline.close()
-    }
-
-    fun getItemById(eventId: EventId): MatrixTimelineItem.Event? {
-        return _timelineItems.value.firstOrNull { (it as? MatrixTimelineItem.Event)?.eventId == eventId } as? MatrixTimelineItem.Event
-    }
-
-    private fun List<MatrixTimelineItem>.hasEncryptionHistoryBanner(): Boolean {
-        val firstItem = firstOrNull()
-        return firstItem is MatrixTimelineItem.Virtual &&
-            firstItem.virtual is VirtualTimelineItem.EncryptedHistoryBanner
-    }
-}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/RustTimeline.kt

@@ -0,0 +1,523 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.timeline
+
+import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.ProgressCallback
+import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.libraries.matrix.api.core.TransactionId
+import io.element.android.libraries.matrix.api.media.AudioInfo
+import io.element.android.libraries.matrix.api.media.FileInfo
+import io.element.android.libraries.matrix.api.media.ImageInfo
+import io.element.android.libraries.matrix.api.media.MediaUploadHandler
+import io.element.android.libraries.matrix.api.media.VideoInfo
+import io.element.android.libraries.matrix.api.poll.PollKind
+import io.element.android.libraries.matrix.api.room.MatrixRoom
+import io.element.android.libraries.matrix.api.room.Mention
+import io.element.android.libraries.matrix.api.room.location.AssetType
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.ReceiptType
+import io.element.android.libraries.matrix.api.timeline.Timeline
+import io.element.android.libraries.matrix.api.timeline.TimelineException
+import io.element.android.libraries.matrix.impl.core.toProgressWatcher
+import io.element.android.libraries.matrix.impl.media.MediaUploadHandlerImpl
+import io.element.android.libraries.matrix.impl.media.map
+import io.element.android.libraries.matrix.impl.media.toMSC3246range
+import io.element.android.libraries.matrix.impl.poll.toInner
+import io.element.android.libraries.matrix.impl.room.RoomContentForwarder
+import io.element.android.libraries.matrix.impl.room.location.toInner
+import io.element.android.libraries.matrix.impl.room.map
+import io.element.android.libraries.matrix.impl.timeline.item.event.EventMessageMapper
+import io.element.android.libraries.matrix.impl.timeline.item.event.EventTimelineItemMapper
+import io.element.android.libraries.matrix.impl.timeline.item.event.TimelineEventContentMapper
+import io.element.android.libraries.matrix.impl.timeline.item.virtual.VirtualTimelineItemMapper
+import io.element.android.libraries.matrix.impl.timeline.postprocessor.LastForwardIndicatorsPostProcessor
+import io.element.android.libraries.matrix.impl.timeline.postprocessor.LoadingIndicatorsPostProcessor
+import io.element.android.libraries.matrix.impl.timeline.postprocessor.RoomBeginningPostProcessor
+import io.element.android.libraries.matrix.impl.timeline.postprocessor.TimelineEncryptedHistoryPostProcessor
+import io.element.android.services.toolbox.api.systemclock.SystemClock
+import kotlinx.coroutines.CompletableDeferred
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.NonCancellable
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.ensureActive
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.getAndUpdate
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import org.matrix.rustcomponents.sdk.EventTimelineItem
+import org.matrix.rustcomponents.sdk.FormattedBody
+import org.matrix.rustcomponents.sdk.MessageFormat
+import org.matrix.rustcomponents.sdk.RoomMessageEventContentWithoutRelation
+import org.matrix.rustcomponents.sdk.SendAttachmentJoinHandle
+import org.matrix.rustcomponents.sdk.TimelineDiff
+import org.matrix.rustcomponents.sdk.TimelineItem
+import org.matrix.rustcomponents.sdk.messageEventContentFromHtml
+import org.matrix.rustcomponents.sdk.messageEventContentFromMarkdown
+import org.matrix.rustcomponents.sdk.use
+import timber.log.Timber
+import uniffi.matrix_sdk_ui.EventItemOrigin
+import java.io.File
+import java.util.Date
+import java.util.concurrent.atomic.AtomicBoolean
+import org.matrix.rustcomponents.sdk.Timeline as InnerTimeline
+
+private const val INITIAL_MAX_SIZE = 50
+private const val PAGINATION_SIZE = 50
+
+class RustTimeline(
+    private val inner: InnerTimeline,
+    isLive: Boolean,
+    systemClock: SystemClock,
+    roomCoroutineScope: CoroutineScope,
+    isKeyBackupEnabled: Boolean,
+    private val matrixRoom: MatrixRoom,
+    private val dispatcher: CoroutineDispatcher,
+    lastLoginTimestamp: Date?,
+    private val roomContentForwarder: RoomContentForwarder,
+    private val onNewSyncedEvent: () -> Unit,
+) : Timeline {
+    private val initLatch = CompletableDeferred<Unit>()
+    private val isInit = AtomicBoolean(false)
+
+    private val _timelineItems: MutableStateFlow<List<MatrixTimelineItem>> =
+        MutableStateFlow(emptyList())
+
+    private val encryptedHistoryPostProcessor = TimelineEncryptedHistoryPostProcessor(
+        lastLoginTimestamp = lastLoginTimestamp,
+        isRoomEncrypted = matrixRoom.isEncrypted,
+        isKeyBackupEnabled = isKeyBackupEnabled,
+        dispatcher = dispatcher,
+    )
+
+    private val roomBeginningPostProcessor = RoomBeginningPostProcessor()
+    private val loadingIndicatorsPostProcessor = LoadingIndicatorsPostProcessor(systemClock)
+    private val lastForwardIndicatorsPostProcessor = LastForwardIndicatorsPostProcessor(isLive)
+
+    private val timelineItemFactory = MatrixTimelineItemMapper(
+        fetchDetailsForEvent = this::fetchDetailsForEvent,
+        roomCoroutineScope = roomCoroutineScope,
+        virtualTimelineItemMapper = VirtualTimelineItemMapper(),
+        eventTimelineItemMapper = EventTimelineItemMapper(
+            contentMapper = TimelineEventContentMapper(
+                eventMessageMapper = EventMessageMapper()
+            )
+        )
+    )
+
+    private val timelineDiffProcessor = MatrixTimelineDiffProcessor(
+        timelineItems = _timelineItems,
+        timelineItemFactory = timelineItemFactory,
+    )
+
+    private val backPaginationStatus = MutableStateFlow(
+        Timeline.PaginationStatus(isPaginating = false, hasMoreToLoad = true)
+    )
+
+    private val forwardPaginationStatus = MutableStateFlow(
+        Timeline.PaginationStatus(isPaginating = false, hasMoreToLoad = !isLive)
+    )
+
+    init {
+        roomCoroutineScope.launch(dispatcher) {
+            inner.timelineDiffFlow { initialList ->
+                postItems(initialList)
+            }.onEach { diffs ->
+                if (diffs.any { diff -> diff.eventOrigin() == EventItemOrigin.SYNC }) {
+                    onNewSyncedEvent()
+                }
+                postDiffs(diffs)
+            }.launchIn(this)
+
+            launch {
+                fetchMembers()
+            }
+        }
+    }
+
+    override val membershipChangeEventReceived: Flow<Unit> = timelineDiffProcessor.membershipChangeEventReceived
+
+    override suspend fun sendReadReceipt(eventId: EventId, receiptType: ReceiptType): Result<Unit> {
+        return runCatching {
+            inner.sendReadReceipt(receiptType.toRustReceiptType(), eventId.value)
+        }
+    }
+
+    private fun updatePaginationStatus(direction: Timeline.PaginationDirection, update: (Timeline.PaginationStatus) -> Timeline.PaginationStatus) {
+        when (direction) {
+            Timeline.PaginationDirection.BACKWARDS -> backPaginationStatus.getAndUpdate(update)
+            Timeline.PaginationDirection.FORWARDS -> forwardPaginationStatus.getAndUpdate(update)
+        }
+    }
+
+    // Use NonCancellable to avoid breaking the timeline when the coroutine is cancelled.
+    override suspend fun paginate(direction: Timeline.PaginationDirection): Result<Boolean> = withContext(NonCancellable) {
+        initLatch.await()
+        runCatching {
+            if (!canPaginate(direction)) throw TimelineException.CannotPaginate
+            updatePaginationStatus(direction) { it.copy(isPaginating = true) }
+            when (direction) {
+                Timeline.PaginationDirection.BACKWARDS -> inner.paginateBackwards(PAGINATION_SIZE.toUShort())
+                Timeline.PaginationDirection.FORWARDS -> inner.focusedPaginateForwards(PAGINATION_SIZE.toUShort())
+            }
+        }.onFailure { error ->
+            updatePaginationStatus(direction) { it.copy(isPaginating = false) }
+            if (error is TimelineException.CannotPaginate) {
+                Timber.d("Can't paginate $direction on room ${matrixRoom.roomId} with paginationStatus: ${backPaginationStatus.value}")
+            } else {
+                Timber.e(error, "Error paginating $direction on room ${matrixRoom.roomId}")
+            }
+        }.onSuccess { hasReachedEnd ->
+            updatePaginationStatus(direction) { it.copy(isPaginating = false, hasMoreToLoad = !hasReachedEnd) }
+        }
+    }
+
+    private fun canPaginate(direction: Timeline.PaginationDirection): Boolean {
+        if (!isInit.get()) return false
+        return when (direction) {
+            Timeline.PaginationDirection.BACKWARDS -> backPaginationStatus.value.canPaginate
+            Timeline.PaginationDirection.FORWARDS -> forwardPaginationStatus.value.canPaginate
+        }
+    }
+
+    override fun paginationStatus(direction: Timeline.PaginationDirection): StateFlow<Timeline.PaginationStatus> {
+        return when (direction) {
+            Timeline.PaginationDirection.BACKWARDS -> backPaginationStatus
+            Timeline.PaginationDirection.FORWARDS -> forwardPaginationStatus
+        }
+    }
+
+    override val timelineItems: Flow<List<MatrixTimelineItem>> = combine(
+        _timelineItems,
+        backPaginationStatus.map { it.hasMoreToLoad }.distinctUntilChanged(),
+        forwardPaginationStatus.map { it.hasMoreToLoad }.distinctUntilChanged(),
+    ) { timelineItems, hasMoreToLoadBackward, hasMoreToLoadForward ->
+        timelineItems
+            .let { items -> encryptedHistoryPostProcessor.process(items) }
+            .let { items ->
+                roomBeginningPostProcessor.process(
+                    items = items,
+                    isDm = matrixRoom.isDm,
+                    hasMoreToLoadBackwards = hasMoreToLoadBackward
+                )
+            }
+            .let { items -> loadingIndicatorsPostProcessor.process(items, hasMoreToLoadBackward, hasMoreToLoadForward) }
+            // Keep lastForwardIndicatorsPostProcessor last
+            .let { items -> lastForwardIndicatorsPostProcessor.process(items) }
+    }
+
+    override fun close() {
+        inner.close()
+        specialModeEventTimelineItem?.destroy()
+    }
+
+    private suspend fun fetchMembers() = withContext(dispatcher) {
+        initLatch.await()
+        try {
+            inner.fetchMembers()
+        } catch (exception: Exception) {
+            Timber.e(exception, "Error fetching members for room ${matrixRoom.roomId}")
+        }
+    }
+
+    private suspend fun postItems(items: List<TimelineItem>) = coroutineScope {
+        // Split the initial items in multiple list as there is no pagination in the cached data, so we can post timelineItems asap.
+        items.chunked(INITIAL_MAX_SIZE).reversed().forEach {
+            ensureActive()
+            timelineDiffProcessor.postItems(it)
+        }
+        isInit.set(true)
+        initLatch.complete(Unit)
+    }
+
+    private suspend fun postDiffs(diffs: List<TimelineDiff>) {
+        initLatch.await()
+        timelineDiffProcessor.postDiffs(diffs)
+    }
+
+    override suspend fun sendMessage(body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit> = withContext(dispatcher) {
+        messageEventContentFromParts(body, htmlBody).withMentions(mentions.map()).use { content ->
+            runCatching {
+                inner.send(content)
+            }
+        }
+    }
+
+    override suspend fun editMessage(
+        originalEventId: EventId?,
+        transactionId: TransactionId?,
+        body: String,
+        htmlBody: String?,
+        mentions: List<Mention>,
+    ): Result<Unit> =
+        withContext(dispatcher) {
+            if (originalEventId != null) {
+                runCatching {
+                    val editedEvent = specialModeEventTimelineItem ?: inner.getEventTimelineItemByEventId(originalEventId.value)
+                    editedEvent.use {
+                        inner.edit(
+                            newContent = messageEventContentFromParts(body, htmlBody).withMentions(mentions.map()),
+                            editItem = it,
+                        )
+                    }
+                    specialModeEventTimelineItem = null
+                }
+            } else {
+                runCatching {
+                    transactionId?.let { cancelSend(it) }
+                    inner.send(messageEventContentFromParts(body, htmlBody))
+                }
+            }
+        }
+
+    private var specialModeEventTimelineItem: EventTimelineItem? = null
+
+    override suspend fun enterSpecialMode(eventId: EventId?): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            specialModeEventTimelineItem?.destroy()
+            specialModeEventTimelineItem = null
+            specialModeEventTimelineItem = eventId?.let { inner.getEventTimelineItemByEventId(it.value) }
+        }.onFailure {
+            Timber.e(it, "Unable to retrieve event for special mode. Are you using the correct timeline?")
+        }
+    }
+
+    override suspend fun replyMessage(eventId: EventId, body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            val inReplyTo = specialModeEventTimelineItem ?: inner.getEventTimelineItemByEventId(eventId.value)
+            inReplyTo.use { eventTimelineItem ->
+                inner.sendReply(messageEventContentFromParts(body, htmlBody).withMentions(mentions.map()), eventTimelineItem)
+            }
+            specialModeEventTimelineItem = null
+        }
+    }
+
+    override suspend fun sendImage(
+        file: File,
+        thumbnailFile: File?,
+        imageInfo: ImageInfo,
+        body: String?,
+        formattedBody: String?,
+        progressCallback: ProgressCallback?,
+    ): Result<MediaUploadHandler> {
+        return sendAttachment(listOfNotNull(file, thumbnailFile)) {
+            inner.sendImage(
+                url = file.path,
+                thumbnailUrl = thumbnailFile?.path,
+                imageInfo = imageInfo.map(),
+                caption = body,
+                formattedCaption = formattedBody?.let {
+                    FormattedBody(body = it, format = MessageFormat.Html)
+                },
+                progressWatcher = progressCallback?.toProgressWatcher()
+            )
+        }
+    }
+
+    override suspend fun sendVideo(
+        file: File,
+        thumbnailFile: File?,
+        videoInfo: VideoInfo,
+        body: String?,
+        formattedBody: String?,
+        progressCallback: ProgressCallback?,
+    ): Result<MediaUploadHandler> {
+        return sendAttachment(listOfNotNull(file, thumbnailFile)) {
+            inner.sendVideo(
+                url = file.path,
+                thumbnailUrl = thumbnailFile?.path,
+                videoInfo = videoInfo.map(),
+                caption = body,
+                formattedCaption = formattedBody?.let {
+                    FormattedBody(body = it, format = MessageFormat.Html)
+                },
+                progressWatcher = progressCallback?.toProgressWatcher()
+            )
+        }
+    }
+
+    override suspend fun sendAudio(file: File, audioInfo: AudioInfo, progressCallback: ProgressCallback?): Result<MediaUploadHandler> {
+        return sendAttachment(listOf(file)) {
+            inner.sendAudio(
+                url = file.path,
+                audioInfo = audioInfo.map(),
+                // Maybe allow a caption in the future?
+                caption = null,
+                formattedCaption = null,
+                progressWatcher = progressCallback?.toProgressWatcher()
+            )
+        }
+    }
+
+    override suspend fun sendFile(file: File, fileInfo: FileInfo, progressCallback: ProgressCallback?): Result<MediaUploadHandler> {
+        return sendAttachment(listOf(file)) {
+            inner.sendFile(file.path, fileInfo.map(), progressCallback?.toProgressWatcher())
+        }
+    }
+
+    override suspend fun toggleReaction(emoji: String, eventId: EventId): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            inner.toggleReaction(key = emoji, eventId = eventId.value)
+        }
+    }
+
+    override suspend fun forwardEvent(eventId: EventId, roomIds: List<RoomId>): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            roomContentForwarder.forward(fromTimeline = inner, eventId = eventId, toRoomIds = roomIds)
+        }.onFailure {
+            Timber.e(it)
+        }
+    }
+
+    override suspend fun retrySendMessage(transactionId: TransactionId): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            inner.retrySend(transactionId.value)
+        }
+    }
+
+    override suspend fun cancelSend(transactionId: TransactionId): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            inner.cancelSend(transactionId.value)
+        }
+    }
+
+    override suspend fun sendLocation(
+        body: String,
+        geoUri: String,
+        description: String?,
+        zoomLevel: Int?,
+        assetType: AssetType?,
+    ): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            inner.sendLocation(
+                body = body,
+                geoUri = geoUri,
+                description = description,
+                zoomLevel = zoomLevel?.toUByte(),
+                assetType = assetType?.toInner(),
+            )
+        }
+    }
+
+    override suspend fun createPoll(
+        question: String,
+        answers: List<String>,
+        maxSelections: Int,
+        pollKind: PollKind,
+    ): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            inner.createPoll(
+                question = question,
+                answers = answers,
+                maxSelections = maxSelections.toUByte(),
+                pollKind = pollKind.toInner(),
+            )
+        }
+    }
+
+    override suspend fun editPoll(
+        pollStartId: EventId,
+        question: String,
+        answers: List<String>,
+        maxSelections: Int,
+        pollKind: PollKind,
+    ): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            val pollStartEvent =
+                inner.getEventTimelineItemByEventId(
+                    eventId = pollStartId.value
+                )
+            pollStartEvent.use {
+                inner.editPoll(
+                    question = question,
+                    answers = answers,
+                    maxSelections = maxSelections.toUByte(),
+                    pollKind = pollKind.toInner(),
+                    editItem = pollStartEvent,
+                )
+            }
+        }
+    }
+
+    override suspend fun sendPollResponse(
+        pollStartId: EventId,
+        answers: List<String>
+    ): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            inner.sendPollResponse(
+                pollStartId = pollStartId.value,
+                answers = answers,
+            )
+        }
+    }
+
+    override suspend fun endPoll(
+        pollStartId: EventId,
+        text: String
+    ): Result<Unit> = withContext(dispatcher) {
+        runCatching {
+            inner.endPoll(
+                pollStartId = pollStartId.value,
+                text = text,
+            )
+        }
+    }
+
+    override suspend fun sendVoiceMessage(
+        file: File,
+        audioInfo: AudioInfo,
+        waveform: List<Float>,
+        progressCallback: ProgressCallback?,
+    ): Result<MediaUploadHandler> = sendAttachment(listOf(file)) {
+        inner.sendVoiceMessage(
+            url = file.path,
+            audioInfo = audioInfo.map(),
+            waveform = waveform.toMSC3246range(),
+            // Maybe allow a caption in the future?
+            caption = null,
+            formattedCaption = null,
+            progressWatcher = progressCallback?.toProgressWatcher(),
+        )
+    }
+
+    private fun messageEventContentFromParts(body: String, htmlBody: String?): RoomMessageEventContentWithoutRelation =
+        if (htmlBody != null) {
+            messageEventContentFromHtml(body, htmlBody)
+        } else {
+            messageEventContentFromMarkdown(body)
+        }
+
+    private fun sendAttachment(files: List<File>, handle: () -> SendAttachmentJoinHandle): Result<MediaUploadHandler> {
+        return runCatching {
+            MediaUploadHandlerImpl(files, handle())
+        }
+    }
+
+    private fun fetchDetailsForEvent(eventId: EventId): Result<Unit> {
+        return runCatching {
+            inner.fetchDetailsForEvent(eventId.value)
+        }
+    }
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/item/event/EventMessageMapper.kt

@@ -57,9 +57,16 @@ class EventMessageMapper {
                         senderProfile = event.senderProfile.map(),
                     )
                 }
-                is RepliedToEventDetails.Error -> InReplyTo.Error
-                is RepliedToEventDetails.Pending -> InReplyTo.Pending
-                is RepliedToEventDetails.Unavailable -> InReplyTo.NotLoaded(inReplyToId)
+                is RepliedToEventDetails.Error -> InReplyTo.Error(
+                    eventId = inReplyToId,
+                    message = event.message,
+                )
+                RepliedToEventDetails.Pending -> InReplyTo.Pending(
+                    eventId = inReplyToId,
+                )
+                is RepliedToEventDetails.Unavailable -> InReplyTo.NotLoaded(
+                    eventId = inReplyToId
+                )
             }
         }
         MessageContent(

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/postprocessor/HasEncryptionHistoryBanner.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.timeline.postprocessor
+
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.item.virtual.VirtualTimelineItem
+
+internal fun List<MatrixTimelineItem>.hasEncryptionHistoryBanner(): Boolean {
+    val firstItem = firstOrNull()
+    return firstItem is MatrixTimelineItem.Virtual &&
+        firstItem.virtual is VirtualTimelineItem.EncryptedHistoryBanner
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/postprocessor/LastForwardIndicatorsPostProcessor.kt

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.timeline.postprocessor
+
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.item.virtual.VirtualTimelineItem
+
+/**
+ * This post processor is responsible for adding virtual items to indicate all the previous last forward item.
+ */
+class LastForwardIndicatorsPostProcessor(
+    private val isTimelineLive: Boolean,
+) {
+    private val lastForwardIdentifiers = LinkedHashSet<String>()
+
+    fun process(
+        items: List<MatrixTimelineItem>,
+    ): List<MatrixTimelineItem> {
+        // If the timeline is live, we don't have any last forward indicator to display
+        if (isTimelineLive) {
+            return items
+        } else {
+            return buildList {
+                val latestEventIdentifier = items.latestEventIdentifier()
+                // Remove if it always exists (this should happen only when no new events are added)
+                lastForwardIdentifiers.remove(latestEventIdentifier)
+
+                items.forEach { item ->
+                    add(item)
+
+                    if (item is MatrixTimelineItem.Event) {
+                        if (lastForwardIdentifiers.contains(item.uniqueId)) {
+                            add(createLastForwardIndicator(item.uniqueId))
+                        }
+                    }
+                }
+                // This is important to always add this one at the end of the list so it's used to keep the scroll position.
+                add(createLastForwardIndicator(latestEventIdentifier))
+                lastForwardIdentifiers.add(latestEventIdentifier)
+            }
+        }
+    }
+}
+
+private fun createLastForwardIndicator(identifier: String): MatrixTimelineItem {
+    return MatrixTimelineItem.Virtual(
+        uniqueId = "last_forward_indicator_$identifier",
+        virtual = VirtualTimelineItem.LastForwardIndicator
+    )
+}
+
+private fun List<MatrixTimelineItem>.latestEventIdentifier(): String {
+    return findLast {
+        it is MatrixTimelineItem.Event
+    }?.let {
+        (it as MatrixTimelineItem.Event).uniqueId
+    } ?: "fake_id"
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/postprocessor/LoadingIndicatorsPostProcessor.kt

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.timeline.postprocessor
+
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.Timeline
+import io.element.android.libraries.matrix.api.timeline.item.virtual.VirtualTimelineItem
+import io.element.android.services.toolbox.api.systemclock.SystemClock
+
+class LoadingIndicatorsPostProcessor(private val systemClock: SystemClock) {
+    fun process(
+        items: List<MatrixTimelineItem>,
+        hasMoreToLoadBackward: Boolean,
+        hasMoreToLoadForward: Boolean,
+    ): List<MatrixTimelineItem> {
+        val shouldAddBackwardLoadingIndicator = hasMoreToLoadBackward && !items.hasEncryptionHistoryBanner()
+        val shouldAddForwardLoadingIndicator = hasMoreToLoadForward && items.isNotEmpty()
+        val currentTimestamp = systemClock.epochMillis()
+        return buildList {
+            if (shouldAddBackwardLoadingIndicator) {
+                val backwardLoadingIndicator = MatrixTimelineItem.Virtual(
+                    uniqueId = "BackwardLoadingIndicator",
+                    virtual = VirtualTimelineItem.LoadingIndicator(
+                        direction = Timeline.PaginationDirection.BACKWARDS,
+                        timestamp = currentTimestamp
+                    )
+                )
+                add(backwardLoadingIndicator)
+            }
+            addAll(items)
+            if (shouldAddForwardLoadingIndicator) {
+                val forwardLoadingIndicator = MatrixTimelineItem.Virtual(
+                    uniqueId = "ForwardLoadingIndicator",
+                    virtual = VirtualTimelineItem.LoadingIndicator(
+                        direction = Timeline.PaginationDirection.FORWARDS,
+                        timestamp = currentTimestamp
+                    )
+                )
+                add(forwardLoadingIndicator)
+            }
+        }
+    }
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/postprocessor/RoomBeginningPostProcessor.kt

@@ -16,23 +16,38 @@
 
 package io.element.android.libraries.matrix.impl.timeline.postprocessor
 
+import androidx.annotation.VisibleForTesting
 import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
 import io.element.android.libraries.matrix.api.timeline.item.event.MembershipChange
 import io.element.android.libraries.matrix.api.timeline.item.event.OtherState
 import io.element.android.libraries.matrix.api.timeline.item.event.RoomMembershipContent
 import io.element.android.libraries.matrix.api.timeline.item.event.StateContent
+import io.element.android.libraries.matrix.api.timeline.item.virtual.VirtualTimelineItem
 
 /**
- * This timeline post-processor removes the room creation event and the self-join event from the timeline for DMs.
+ * This timeline post-processor removes the room creation event and the self-join event from the timeline for DMs
+ * or add the RoomBeginning item for non DM room.
  */
-class DmBeginningTimelineProcessor {
+class RoomBeginningPostProcessor {
     fun process(
         items: List<MatrixTimelineItem>,
         isDm: Boolean,
-        isAtStartOfTimeline: Boolean
+        hasMoreToLoadBackwards: Boolean
     ): List<MatrixTimelineItem> {
-        if (!isDm || !isAtStartOfTimeline) return items
+        return when {
+            hasMoreToLoadBackwards -> items
+            isDm -> processForDM(items)
+            else -> processForRoom(items)
+        }
+    }
 
+    private fun processForRoom(items: List<MatrixTimelineItem>): List<MatrixTimelineItem> {
+        if (items.hasEncryptionHistoryBanner()) return items
+        val roomBeginningItem = createRoomBeginningItem()
+        return listOf(roomBeginningItem) + items
+    }
+
+    private fun processForDM(items: List<MatrixTimelineItem>): List<MatrixTimelineItem> {
         // Find room creation event. This is usually index 0
         val roomCreationEventIndex = items.indexOfFirst {
             val stateEventContent = (it as? MatrixTimelineItem.Event)?.event?.content as? StateContent
@@ -58,4 +73,12 @@ class DmBeginningTimelineProcessor {
         }
         return newItems
     }
+
+    @VisibleForTesting
+    fun createRoomBeginningItem(): MatrixTimelineItem.Virtual {
+        return MatrixTimelineItem.Virtual(
+            uniqueId = VirtualTimelineItem.RoomBeginning.toString(),
+            virtual = VirtualTimelineItem.RoomBeginning
+        )
+    }
 }

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/timeline/postprocessor/RoomBeginningPostProcessorTest.kt

@@ -22,21 +22,22 @@ import io.element.android.libraries.matrix.api.timeline.item.event.MembershipCha
 import io.element.android.libraries.matrix.api.timeline.item.event.OtherState
 import io.element.android.libraries.matrix.api.timeline.item.event.RoomMembershipContent
 import io.element.android.libraries.matrix.api.timeline.item.event.StateContent
+import io.element.android.libraries.matrix.api.timeline.item.virtual.VirtualTimelineItem
 import io.element.android.libraries.matrix.test.A_USER_ID
 import io.element.android.libraries.matrix.test.A_USER_ID_2
 import io.element.android.libraries.matrix.test.timeline.aMessageContent
 import io.element.android.libraries.matrix.test.timeline.anEventTimelineItem
 import org.junit.Test
 
-class DmBeginningTimelineProcessorTest {
+class RoomBeginningPostProcessorTest {
     @Test
     fun `processor removes room creation event and self-join event from DM timeline`() {
         val timelineItems = listOf(
             MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
             MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
         )
-        val processor = DmBeginningTimelineProcessor()
-        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = true)
+        val processor = RoomBeginningPostProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, hasMoreToLoadBackwards = false)
         assertThat(processedItems).isEmpty()
     }
 
@@ -52,19 +53,31 @@ class DmBeginningTimelineProcessorTest {
             MatrixTimelineItem.Event("m.room.member_other", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID_2, MembershipChange.JOINED))),
             MatrixTimelineItem.Event("m.room.message", anEventTimelineItem(content = aMessageContent("hi"))),
         )
-        val processor = DmBeginningTimelineProcessor()
-        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = true)
+        val processor = RoomBeginningPostProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, hasMoreToLoadBackwards = false)
         assertThat(processedItems).isEqualTo(expected)
     }
 
     @Test
-    fun `processor won't remove items if it's not a DM`() {
+    fun `processor will add beginning of room item if it's not a DM`() {
         val timelineItems = listOf(
             MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
             MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
         )
-        val processor = DmBeginningTimelineProcessor()
-        val processedItems = processor.process(timelineItems, isDm = false, isAtStartOfTimeline = true)
+        val processor = RoomBeginningPostProcessor()
+        val processedItems = processor.process(timelineItems, isDm = false, hasMoreToLoadBackwards = false)
+        assertThat(processedItems).isEqualTo(
+            listOf(processor.createRoomBeginningItem()) + timelineItems
+        )
+    }
+
+    @Test
+    fun `processor will not add beginning of room item if it's not a DM and EncryptedHistoryBanner item is found`() {
+        val timelineItems = listOf(
+            MatrixTimelineItem.Virtual("EncryptedHistoryBanner", VirtualTimelineItem.EncryptedHistoryBanner),
+        )
+        val processor = RoomBeginningPostProcessor()
+        val processedItems = processor.process(timelineItems, isDm = false, hasMoreToLoadBackwards = false)
         assertThat(processedItems).isEqualTo(timelineItems)
     }
 
@@ -74,8 +87,8 @@ class DmBeginningTimelineProcessorTest {
             MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
             MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
         )
-        val processor = DmBeginningTimelineProcessor()
-        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = false)
+        val processor = RoomBeginningPostProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, hasMoreToLoadBackwards = true)
         assertThat(processedItems).isEqualTo(timelineItems)
     }
 
@@ -84,8 +97,8 @@ class DmBeginningTimelineProcessorTest {
         val timelineItems = listOf(
             MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
         )
-        val processor = DmBeginningTimelineProcessor()
-        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = false)
+        val processor = RoomBeginningPostProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, hasMoreToLoadBackwards = true)
         assertThat(processedItems).isEqualTo(timelineItems)
     }
 
@@ -95,8 +108,8 @@ class DmBeginningTimelineProcessorTest {
             MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
             MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID_2, MembershipChange.JOINED))),
         )
-        val processor = DmBeginningTimelineProcessor()
-        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = false)
+        val processor = RoomBeginningPostProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, hasMoreToLoadBackwards = true)
         assertThat(processedItems).isEqualTo(timelineItems)
     }
 }

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt

@@ -43,8 +43,8 @@ import io.element.android.libraries.matrix.api.room.StateEventType
 import io.element.android.libraries.matrix.api.room.location.AssetType
 import io.element.android.libraries.matrix.api.room.powerlevels.MatrixRoomPowerLevels
 import io.element.android.libraries.matrix.api.room.powerlevels.UserRoleChange
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
 import io.element.android.libraries.matrix.api.timeline.ReceiptType
+import io.element.android.libraries.matrix.api.timeline.Timeline
 import io.element.android.libraries.matrix.api.timeline.item.event.EventTimelineItem
 import io.element.android.libraries.matrix.api.widget.MatrixWidgetDriver
 import io.element.android.libraries.matrix.api.widget.MatrixWidgetSettings
@@ -54,7 +54,7 @@ import io.element.android.libraries.matrix.test.A_ROOM_NAME
 import io.element.android.libraries.matrix.test.A_SESSION_ID
 import io.element.android.libraries.matrix.test.media.FakeMediaUploadHandler
 import io.element.android.libraries.matrix.test.notificationsettings.FakeNotificationSettingsService
-import io.element.android.libraries.matrix.test.timeline.FakeMatrixTimeline
+import io.element.android.libraries.matrix.test.timeline.FakeTimeline
 import io.element.android.libraries.matrix.test.widget.FakeWidgetDriver
 import io.element.android.tests.testutils.simulateLongTask
 import kotlinx.collections.immutable.ImmutableMap
@@ -84,7 +84,7 @@ class FakeMatrixRoom(
     override val joinedMemberCount: Long = 123L,
     override val activeMemberCount: Long = 234L,
     val notificationSettingsService: NotificationSettingsService = FakeNotificationSettingsService(),
-    private val matrixTimeline: MatrixTimeline = FakeMatrixTimeline(),
+    override val liveTimeline: Timeline = FakeTimeline(),
     private var roomPermalinkResult: () -> Result<String> = { Result.success("room link") },
     private var eventPermalinkResult: (EventId) -> Result<String> = { Result.success("event link") },
     canRedactOwn: Boolean = false,
@@ -134,7 +134,6 @@ class FakeMatrixRoom(
     private var updatePowerLevelsResult = Result.success(Unit)
     private var resetPowerLevelsResult = Result.success(defaultRoomPowerLevels())
     var sendMessageMentions = emptyList<Mention>()
-    val editMessageCalls = mutableListOf<Pair<String, String?>>()
     private val _typingRecord = mutableListOf<Boolean>()
     val typingRecord: List<Boolean>
         get() = _typingRecord
@@ -215,7 +214,15 @@ class FakeMatrixRoom(
 
     override val syncUpdateFlow: StateFlow<Long> = MutableStateFlow(0L)
 
-    override val timeline: MatrixTimeline = matrixTimeline
+    private var timelineFocusedOnEventResult: Result<Timeline> = Result.success(FakeTimeline())
+
+    fun givenTimelineFocusedOnEventResult(result: Result<Timeline>) {
+        timelineFocusedOnEventResult = result
+    }
+
+    override suspend fun timelineFocusedOnEvent(eventId: EventId): Result<Timeline> = simulateLongTask {
+        timelineFocusedOnEventResult
+    }
 
     override suspend fun subscribeToSync() = Unit
 
@@ -288,31 +295,6 @@ class FakeMatrixRoom(
         return eventPermalinkResult(eventId)
     }
 
-    override suspend fun editMessage(
-        originalEventId: EventId?,
-        transactionId: TransactionId?,
-        body: String,
-        htmlBody: String?,
-        mentions: List<Mention>
-    ): Result<Unit> {
-        sendMessageMentions = mentions
-        editMessageCalls += body to htmlBody
-        return Result.success(Unit)
-    }
-
-    var replyMessageParameter: Pair<String, String?>? = null
-        private set
-
-    override suspend fun enterSpecialMode(eventId: EventId?): Result<Unit> {
-        return Result.success(Unit)
-    }
-
-    override suspend fun replyMessage(eventId: EventId, body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit> {
-        sendMessageMentions = mentions
-        replyMessageParameter = body to htmlBody
-        return Result.success(Unit)
-    }
-
     var redactEventEventIdParam: EventId? = null
         private set
 

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/timeline/FakeMatrixTimeline.kt

@@ -1,97 +0,0 @@
-/*
- * Copyright (c) 2023 New Vector Ltd
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.element.android.libraries.matrix.test.timeline
-
-import io.element.android.libraries.matrix.api.core.EventId
-import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
-import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
-import io.element.android.libraries.matrix.api.timeline.ReceiptType
-import io.element.android.tests.testutils.simulateLongTask
-import kotlinx.coroutines.CompletableDeferred
-import kotlinx.coroutines.delay
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.MutableSharedFlow
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.getAndUpdate
-
-class FakeMatrixTimeline(
-    initialTimelineItems: List<MatrixTimelineItem> = emptyList(),
-    initialPaginationState: MatrixTimeline.PaginationState = MatrixTimeline.PaginationState(
-        hasMoreToLoadBackwards = true,
-        isBackPaginating = false,
-        beginningOfRoomReached = false,
-    )
-) : MatrixTimeline {
-    private val _paginationState: MutableStateFlow<MatrixTimeline.PaginationState> = MutableStateFlow(initialPaginationState)
-    private val _timelineItems: MutableStateFlow<List<MatrixTimelineItem>> = MutableStateFlow(initialTimelineItems)
-
-    var sentReadReceipts = mutableListOf<Pair<EventId, ReceiptType>>()
-        private set
-
-    var sendReadReceiptLatch: CompletableDeferred<Unit>? = null
-
-    fun updatePaginationState(update: (MatrixTimeline.PaginationState.() -> MatrixTimeline.PaginationState)) {
-        _paginationState.getAndUpdate(update)
-    }
-
-    fun updateTimelineItems(update: (items: List<MatrixTimelineItem>) -> List<MatrixTimelineItem>) {
-        _timelineItems.getAndUpdate(update)
-    }
-
-    override val paginationState: StateFlow<MatrixTimeline.PaginationState> = _paginationState
-
-    override val timelineItems: Flow<List<MatrixTimelineItem>> = _timelineItems
-
-    override suspend fun paginateBackwards(requestSize: Int) = paginateBackwards()
-    override suspend fun paginateBackwards(requestSize: Int, untilNumberOfItems: Int) = paginateBackwards()
-
-    override val membershipChangeEventReceived = MutableSharedFlow<Unit>()
-
-    private suspend fun paginateBackwards(): Result<Unit> {
-        updatePaginationState {
-            copy(isBackPaginating = true)
-        }
-        delay(100)
-        updatePaginationState {
-            copy(isBackPaginating = false)
-        }
-        updateTimelineItems { timelineItems ->
-            timelineItems
-        }
-        return Result.success(Unit)
-    }
-
-    fun givenMembershipChangeEventReceived() {
-        membershipChangeEventReceived.tryEmit(Unit)
-    }
-
-    override suspend fun fetchDetailsForEvent(eventId: EventId): Result<Unit> = simulateLongTask {
-        Result.success(Unit)
-    }
-
-    override suspend fun sendReadReceipt(
-        eventId: EventId,
-        receiptType: ReceiptType,
-    ): Result<Unit> = simulateLongTask {
-        sentReadReceipts.add(eventId to receiptType)
-        sendReadReceiptLatch?.complete(Unit)
-        Result.success(Unit)
-    }
-
-    override fun close() = Unit
-}

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/timeline/FakeTimeline.kt

@@ -0,0 +1,372 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.test.timeline
+
+import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.ProgressCallback
+import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.libraries.matrix.api.core.TransactionId
+import io.element.android.libraries.matrix.api.media.AudioInfo
+import io.element.android.libraries.matrix.api.media.FileInfo
+import io.element.android.libraries.matrix.api.media.ImageInfo
+import io.element.android.libraries.matrix.api.media.MediaUploadHandler
+import io.element.android.libraries.matrix.api.media.VideoInfo
+import io.element.android.libraries.matrix.api.poll.PollKind
+import io.element.android.libraries.matrix.api.room.Mention
+import io.element.android.libraries.matrix.api.room.location.AssetType
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.ReceiptType
+import io.element.android.libraries.matrix.api.timeline.Timeline
+import io.element.android.libraries.matrix.test.media.FakeMediaUploadHandler
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import java.io.File
+
+class FakeTimeline(
+    private val name: String = "FakeTimeline",
+    override val timelineItems: Flow<List<MatrixTimelineItem>> = MutableStateFlow(emptyList()),
+    private val backwardPaginationStatus: MutableStateFlow<Timeline.PaginationStatus> = MutableStateFlow(
+        Timeline.PaginationStatus(
+            isPaginating = false,
+            hasMoreToLoad = true
+        )
+    ),
+    private val forwardPaginationStatus: MutableStateFlow<Timeline.PaginationStatus> = MutableStateFlow(
+        Timeline.PaginationStatus(
+            isPaginating = false,
+            hasMoreToLoad = false
+        )
+    ),
+    override val membershipChangeEventReceived: Flow<Unit> = MutableSharedFlow(),
+) : Timeline {
+    var sendMessageLambda: (
+        body: String,
+        htmlBody: String?,
+        mentions: List<Mention>,
+    ) -> Result<Unit> = { _, _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun sendMessage(
+        body: String,
+        htmlBody: String?,
+        mentions: List<Mention>,
+    ): Result<Unit> = sendMessageLambda(body, htmlBody, mentions)
+
+    var editMessageLambda: (
+        originalEventId: EventId?,
+        transactionId: TransactionId?,
+        body: String,
+        htmlBody: String?,
+        mentions: List<Mention>,
+    ) -> Result<Unit> = { _, _, _, _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun editMessage(
+        originalEventId: EventId?,
+        transactionId: TransactionId?,
+        body: String,
+        htmlBody: String?,
+        mentions: List<Mention>,
+    ): Result<Unit> = editMessageLambda(
+        originalEventId,
+        transactionId,
+        body,
+        htmlBody,
+        mentions
+    )
+
+    var enterSpecialModeLambda: (eventId: EventId?) -> Result<Unit> = {
+        Result.success(Unit)
+    }
+
+    override suspend fun enterSpecialMode(eventId: EventId?): Result<Unit> = enterSpecialModeLambda(eventId)
+
+    var replyMessageLambda: (
+        eventId: EventId,
+        body: String,
+        htmlBody: String?,
+        mentions: List<Mention>,
+    ) -> Result<Unit> = { _, _, _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun replyMessage(
+        eventId: EventId,
+        body: String,
+        htmlBody: String?,
+        mentions: List<Mention>,
+    ): Result<Unit> = replyMessageLambda(
+        eventId,
+        body,
+        htmlBody,
+        mentions
+    )
+
+    var sendImageLambda: (
+        file: File,
+        thumbnailFile: File?,
+        imageInfo: ImageInfo,
+        body: String?,
+        formattedBody: String?,
+        progressCallback: ProgressCallback?,
+    ) -> Result<MediaUploadHandler> = { _, _, _, _, _, _ ->
+        Result.success(FakeMediaUploadHandler())
+    }
+
+    override suspend fun sendImage(
+        file: File,
+        thumbnailFile: File?,
+        imageInfo: ImageInfo,
+        body: String?,
+        formattedBody: String?,
+        progressCallback: ProgressCallback?,
+    ): Result<MediaUploadHandler> = sendImageLambda(
+        file,
+        thumbnailFile,
+        imageInfo,
+        body,
+        formattedBody,
+        progressCallback
+    )
+
+    var sendVideoLambda: (
+        file: File,
+        thumbnailFile: File?,
+        videoInfo: VideoInfo,
+        body: String?,
+        formattedBody: String?,
+        progressCallback: ProgressCallback?,
+    ) -> Result<MediaUploadHandler> = { _, _, _, _, _, _ ->
+        Result.success(FakeMediaUploadHandler())
+    }
+
+    override suspend fun sendVideo(
+        file: File,
+        thumbnailFile: File?,
+        videoInfo: VideoInfo,
+        body: String?,
+        formattedBody: String?,
+        progressCallback: ProgressCallback?,
+    ): Result<MediaUploadHandler> = sendVideoLambda(
+        file,
+        thumbnailFile,
+        videoInfo,
+        body,
+        formattedBody,
+        progressCallback
+    )
+
+    var sendAudioLambda: (
+        file: File,
+        audioInfo: AudioInfo,
+        progressCallback: ProgressCallback?,
+    ) -> Result<MediaUploadHandler> = { _, _, _ ->
+        Result.success(FakeMediaUploadHandler())
+    }
+
+    override suspend fun sendAudio(
+        file: File,
+        audioInfo: AudioInfo,
+        progressCallback: ProgressCallback?,
+    ): Result<MediaUploadHandler> = sendAudioLambda(
+        file,
+        audioInfo,
+        progressCallback
+    )
+
+    var sendFileLambda: (
+        file: File,
+        fileInfo: FileInfo,
+        progressCallback: ProgressCallback?,
+    ) -> Result<MediaUploadHandler> = { _, _, _ ->
+        Result.success(FakeMediaUploadHandler())
+    }
+
+    override suspend fun sendFile(
+        file: File,
+        fileInfo: FileInfo,
+        progressCallback: ProgressCallback?,
+    ): Result<MediaUploadHandler> = sendFileLambda(
+        file,
+        fileInfo,
+        progressCallback
+    )
+
+    var toggleReactionLambda: (emoji: String, eventId: EventId) -> Result<Unit> = { _, _ -> Result.success(Unit) }
+    override suspend fun toggleReaction(emoji: String, eventId: EventId): Result<Unit> = toggleReactionLambda(emoji, eventId)
+
+    var forwardEventLambda: (eventId: EventId, roomIds: List<RoomId>) -> Result<Unit> = { _, _ -> Result.success(Unit) }
+    override suspend fun forwardEvent(eventId: EventId, roomIds: List<RoomId>): Result<Unit> = forwardEventLambda(eventId, roomIds)
+
+    var retrySendMessageLambda: (transactionId: TransactionId) -> Result<Unit> = { Result.success(Unit) }
+    override suspend fun retrySendMessage(transactionId: TransactionId): Result<Unit> = retrySendMessageLambda(transactionId)
+
+    var cancelSendLambda: (transactionId: TransactionId) -> Result<Unit> = { Result.success(Unit) }
+    override suspend fun cancelSend(transactionId: TransactionId): Result<Unit> = cancelSendLambda(transactionId)
+
+    var sendLocationLambda: (
+        body: String,
+        geoUri: String,
+        description: String?,
+        zoomLevel: Int?,
+        assetType: AssetType?,
+    ) -> Result<Unit> = { _, _, _, _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun sendLocation(
+        body: String,
+        geoUri: String,
+        description: String?,
+        zoomLevel: Int?,
+        assetType: AssetType?,
+    ): Result<Unit> = sendLocationLambda(
+        body,
+        geoUri,
+        description,
+        zoomLevel,
+        assetType
+    )
+
+    var createPollLambda: (
+        question: String,
+        answers: List<String>,
+        maxSelections: Int,
+        pollKind: PollKind,
+    ) -> Result<Unit> = { _, _, _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun createPoll(
+        question: String,
+        answers: List<String>,
+        maxSelections: Int,
+        pollKind: PollKind,
+    ): Result<Unit> = createPollLambda(
+        question,
+        answers,
+        maxSelections,
+        pollKind
+    )
+
+    var editPollLambda: (
+        pollStartId: EventId,
+        question: String,
+        answers: List<String>,
+        maxSelections: Int,
+        pollKind: PollKind,
+    ) -> Result<Unit> = { _, _, _, _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun editPoll(
+        pollStartId: EventId,
+        question: String,
+        answers: List<String>,
+        maxSelections: Int,
+        pollKind: PollKind,
+    ): Result<Unit> = editPollLambda(
+        pollStartId,
+        question,
+        answers,
+        maxSelections,
+        pollKind
+    )
+
+    var sendPollResponseLambda: (
+        pollStartId: EventId,
+        answers: List<String>,
+    ) -> Result<Unit> = { _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun sendPollResponse(
+        pollStartId: EventId,
+        answers: List<String>,
+    ): Result<Unit> = sendPollResponseLambda(pollStartId, answers)
+
+    var endPollLambda: (
+        pollStartId: EventId,
+        text: String,
+    ) -> Result<Unit> = { _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun endPoll(
+        pollStartId: EventId,
+        text: String,
+    ): Result<Unit> = endPollLambda(pollStartId, text)
+
+    var sendVoiceMessageLambda: (
+        file: File,
+        audioInfo: AudioInfo,
+        waveform: List<Float>,
+        progressCallback: ProgressCallback?,
+    ) -> Result<MediaUploadHandler> = { _, _, _, _ ->
+        Result.success(FakeMediaUploadHandler())
+    }
+
+    override suspend fun sendVoiceMessage(
+        file: File,
+        audioInfo: AudioInfo,
+        waveform: List<Float>,
+        progressCallback: ProgressCallback?,
+    ): Result<MediaUploadHandler> = sendVoiceMessageLambda(
+        file,
+        audioInfo,
+        waveform,
+        progressCallback
+    )
+
+    var sendReadReceiptLambda: (
+        eventId: EventId,
+        receiptType: ReceiptType,
+    ) -> Result<Unit> = { _, _ ->
+        Result.success(Unit)
+    }
+
+    override suspend fun sendReadReceipt(
+        eventId: EventId,
+        receiptType: ReceiptType,
+    ): Result<Unit> = sendReadReceiptLambda(eventId, receiptType)
+
+    var paginateLambda: (direction: Timeline.PaginationDirection) -> Result<Boolean> = {
+        Result.success(false)
+    }
+
+    override suspend fun paginate(direction: Timeline.PaginationDirection): Result<Boolean> = paginateLambda(direction)
+
+    override fun paginationStatus(direction: Timeline.PaginationDirection): StateFlow<Timeline.PaginationStatus> {
+        return when (direction) {
+            Timeline.PaginationDirection.BACKWARDS -> backwardPaginationStatus
+            Timeline.PaginationDirection.FORWARDS -> forwardPaginationStatus
+        }
+    }
+
+    var closeCounter = 0
+        private set
+
+    override fun close() {
+        closeCounter++
+    }
+
+    override fun toString() = "FakeTimeline: $name"
+}

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/timeline/LiveTimelineProvider.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.test.timeline
+
+import io.element.android.libraries.matrix.api.room.MatrixRoom
+import io.element.android.libraries.matrix.api.timeline.Timeline
+import io.element.android.libraries.matrix.api.timeline.TimelineProvider
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+
+class LiveTimelineProvider(
+    private val room: MatrixRoom,
+) : TimelineProvider {
+    override fun activeTimelineFlow(): StateFlow<Timeline> = MutableStateFlow(room.liveTimeline)
+}

samples/minimal/src/main/kotlin/io/element/android/samples/minimal/RoomListScreen.kt

@@ -49,6 +49,7 @@ import io.element.android.libraries.indicator.impl.DefaultIndicatorService
 import io.element.android.libraries.matrix.api.MatrixClient
 import io.element.android.libraries.matrix.api.core.RoomId
 import io.element.android.libraries.matrix.api.room.RoomMembershipObserver
+import io.element.android.libraries.matrix.api.timeline.Timeline
 import io.element.android.libraries.preferences.impl.store.DefaultSessionPreferencesStore
 import io.element.android.libraries.push.test.notifications.FakeNotificationDrawerManager
 import io.element.android.services.analytics.noop.NoopAnalyticsService
@@ -145,7 +146,7 @@ class RoomListScreen(
             Singleton.appScope.launch {
                 withContext(coroutineDispatchers.io) {
                     matrixClient.getRoom(roomId)!!.use { room ->
-                        room.timeline.paginateBackwards(20, 50)
+                        room.liveTimeline.paginate(Timeline.PaginationDirection.BACKWARDS)
                     }
                 }
             }

tests/testutils/src/main/kotlin/io/element/android/tests/testutils/lambda/LambdaRecorder.kt

@@ -71,6 +71,13 @@ inline fun <reified T1, reified T2, reified T3, reified T4, reified R> lambdaRec
     return LambdaFourParamsRecorder(ensureNeverCalled, block)
 }
 
+inline fun <reified T1, reified T2, reified T3, reified T4, reified T5, reified R> lambdaRecorder(
+    ensureNeverCalled: Boolean = false,
+    noinline block: (T1, T2, T3, T4, T5) -> R
+): LambdaFiveParamsRecorder<T1, T2, T3, T4, T5, R> {
+    return LambdaFiveParamsRecorder(ensureNeverCalled, block)
+}
+
 class LambdaNoParamRecorder<out R>(ensureNeverCalled: Boolean, val block: () -> R) : LambdaRecorder(ensureNeverCalled), () -> R {
     override fun invoke(): R {
         onInvoke()
@@ -109,3 +116,12 @@ class LambdaFourParamsRecorder<in T1, in T2, in T3, in T4, out R>(ensureNeverCal
         return block(p1, p2, p3, p4)
     }
 }
+
+class LambdaFiveParamsRecorder<in T1, in T2, in T3, in T4, in T5, out R>(ensureNeverCalled: Boolean, val block: (T1, T2, T3, T4, T5) -> R) : LambdaRecorder(
+    ensureNeverCalled
+), (T1, T2, T3, T4, T5) -> R {
+    override fun invoke(p1: T1, p2: T2, p3: T3, p4: T4, p5: T5): R {
+        onInvoke(p1, p2, p3, p4, p5)
+        return block(p1, p2, p3, p4, p5)
+    }
+}