From 82d833b4349b4f760d175b5286d9c76e0d69b4e4 Mon Sep 17 00:00:00 2001
From: ganfra <francoisg@matrix.org>
Date: Thu, 25 Apr 2024 17:41:10 +0200
Subject: [PATCH] Timeline permalink : scroll to fetched event when known

---
 .../messages/impl/timeline/TimelinePresenter.kt | 17 +++++++++++------
 .../messages/impl/timeline/TimelineState.kt     |  1 +
 .../messages/impl/timeline/TimelineView.kt      |  4 ++--
 .../components/TimelineItemVirtualRow.kt        |  2 +-
 4 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelinePresenter.kt b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelinePresenter.kt
index f3ba877888..61b2add5cb 100644
--- a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelinePresenter.kt
+++ b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelinePresenter.kt
@@ -146,7 +146,7 @@ class TimelinePresenter @AssistedInject constructor(
                         timelineController.focusOnEvent(event.eventId)
                             .fold(
                                 onSuccess = {
-                                    focusRequestState.value = FocusRequestState.None
+                                    focusRequestState.value = FocusRequestState.Fetched
                                 },
                                 onFailure = {
                                     focusRequestState.value = FocusRequestState.Failure(it)
@@ -165,15 +165,20 @@ class TimelinePresenter @AssistedInject constructor(
             }
         }
 
-        // Makes sure to get back to live when there is nothing more to load forwards
-        LaunchedEffect(isLive) {
-
-        }
-
         LaunchedEffect(timelineItems.size) {
             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(timelineController.timelineItems(), room.membersStateFlow) { items, membersState ->
                 timelineItemsFactory.replaceWith(
diff --git a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineState.kt b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineState.kt
index 4a345af90c..67a7dac574 100644
--- a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineState.kt
+++ b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineState.kt
@@ -40,6 +40,7 @@ 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
 }
 
diff --git a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineView.kt b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineView.kt
index db7b89833b..101ad58703 100644
--- a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineView.kt
+++ b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineView.kt
@@ -195,7 +195,7 @@ private fun FocusRequestStateView(
         FocusRequestState.Fetching -> {
             ProgressDialog(modifier = modifier, onDismissRequest = onClearFocusRequestState)
         }
-        is FocusRequestState.Cached, FocusRequestState.None -> Unit
+        else -> Unit
     }
 }
 
@@ -237,7 +237,7 @@ private fun BoxScope.TimelineScrollHelper(
         }
     }
 
-    LaunchedEffect(key1 = focusRequestState) {
+    LaunchedEffect(focusRequestState) {
         if (focusRequestState is FocusRequestState.Cached) {
             if (abs(lazyListState.firstVisibleItemIndex - focusRequestState.index) < 10) {
                 lazyListState.animateScrollToItem(focusRequestState.index)
diff --git a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemVirtualRow.kt b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemVirtualRow.kt
index 9dd1210af0..df9d355dbf 100644
--- a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemVirtualRow.kt
+++ b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemVirtualRow.kt
@@ -51,7 +51,7 @@ fun TimelineItemVirtualRow(
             TimelineItemRoomBeginningModel -> TimelineItemRoomBeginningView(roomName = timelineRoomInfo.name)
             is TimelineItemLoadingIndicatorModel -> {
                 TimelineLoadingMoreIndicator()
-                LaunchedEffect(key1 = virtual.model.timestamp) {
+                LaunchedEffect(virtual.model.timestamp) {
                     eventSink(TimelineEvents.LoadMore(virtual.model.direction))
                 }
             }