TimelineItemPresenterFactories (#1609)

DI infrastructure to allow injection of presenters into the timeline.
Add an `@AssistedFactory` of type `TimelineItemPresenterFactory` to a `Presenter` class and bind this factory into the TimelineItemPresenterFactory map multi binding using:

```
@Binds
@IntoMap
@TimelineItemEventContentKey(MyTimelineItemContent::class)
```

A map multibinding of such factories will be available in the `LocalTimelineItemPresenterFactories` composition local for further use down the UI tree.

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

@@ -17,6 +17,7 @@
 package io.element.android.features.messages.impl
 
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.ui.Modifier
 import com.bumble.appyx.core.lifecycle.subscribe
 import com.bumble.appyx.core.modality.BuildContext
@@ -28,6 +29,8 @@ 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.model.TimelineItem
+import io.element.android.features.messages.impl.timeline.di.LocalTimelineItemPresenterFactories
+import io.element.android.features.messages.impl.timeline.di.TimelineItemPresenterFactories
 import io.element.android.libraries.di.RoomScope
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.UserId
@@ -44,6 +47,7 @@ class MessagesNode @AssistedInject constructor(
     private val room: MatrixRoom,
     private val analyticsService: AnalyticsService,
     private val presenterFactory: MessagesPresenter.Factory,
+    private val timelineItemPresenterFactories: TimelineItemPresenterFactories,
 ) : Node(buildContext, plugins = plugins), MessagesNavigator {
 
     private val presenter = presenterFactory.create(this)
@@ -106,17 +110,21 @@ class MessagesNode @AssistedInject constructor(
 
     @Composable
     override fun View(modifier: Modifier) {
-        val state = presenter.present()
-        MessagesView(
-            state = state,
-            onBackPressed = this::navigateUp,
-            onRoomDetailsClicked = this::onRoomDetailsClicked,
-            onEventClicked = this::onEventClicked,
-            onPreviewAttachments = this::onPreviewAttachments,
-            onUserDataClicked = this::onUserDataClicked,
-            onSendLocationClicked = this::onSendLocationClicked,
-            onCreatePollClicked = this::onCreatePollClicked,
-            modifier = modifier,
-        )
+        CompositionLocalProvider(
+            LocalTimelineItemPresenterFactories provides timelineItemPresenterFactories,
+        ) {
+            val state = presenter.present()
+            MessagesView(
+                state = state,
+                onBackPressed = this::navigateUp,
+                onRoomDetailsClicked = this::onRoomDetailsClicked,
+                onEventClicked = this::onEventClicked,
+                onPreviewAttachments = this::onPreviewAttachments,
+                onUserDataClicked = this::onUserDataClicked,
+                onSendLocationClicked = this::onSendLocationClicked,
+                onCreatePollClicked = this::onCreatePollClicked,
+                modifier = modifier,
+            )
+        }
     }
 }

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

@@ -0,0 +1,29 @@
+/*
+ * 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.features.messages.impl.timeline.di
+
+import dagger.MapKey
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEventContent
+import kotlin.reflect.KClass
+
+/**
+ * Annotation to add a factory of type [TimelineItemPresenterFactory] to a
+ * Dagger map multi binding keyed with a subclass of [TimelineItemEventContent].
+ */
+@Retention(AnnotationRetention.RUNTIME)
+@MapKey
+annotation class TimelineItemEventContentKey(val value: KClass<out TimelineItemEventContent>)

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

@@ -0,0 +1,77 @@
+/*
+ * 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.features.messages.impl.timeline.di
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.staticCompositionLocalOf
+import com.squareup.anvil.annotations.ContributesTo
+import dagger.Module
+import dagger.multibindings.Multibinds
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEventContent
+import io.element.android.libraries.architecture.Presenter
+import io.element.android.libraries.di.RoomScope
+import javax.inject.Inject
+
+/**
+ * Dagger module that declares the [TimelineItemPresenterFactory] map multi binding.
+ *
+ * Its sole purpose is to support the case of an empty map multibinding.
+ */
+@Module
+@ContributesTo(RoomScope::class)
+interface TimelineItemPresenterFactoriesModule {
+    @Multibinds
+    fun multiBindTimelineItemPresenterFactories(): @JvmSuppressWildcards Map<Class<out TimelineItemEventContent>, TimelineItemPresenterFactory<*, *>>
+}
+
+/**
+ * Wrapper around the [TimelineItemPresenterFactory] map multi binding.
+ *
+ * Its only purpose is to provide a nicer type name than:
+ * `@JvmSuppressWildcards Map<Class<out TimelineItemEventContent>, TimelineItemPresenterFactory<*, *>>`.
+ *
+ * A typealias would have been better but typealiases on Dagger types which use @JvmSuppressWildcards
+ * currently make Dagger crash.
+ *
+ * Request this type from Dagger to access the [TimelineItemPresenterFactory] map multibinding.
+ */
+data class TimelineItemPresenterFactories @Inject constructor(
+    val factories: @JvmSuppressWildcards Map<Class<out TimelineItemEventContent>, TimelineItemPresenterFactory<*, *>>,
+)
+
+/**
+ * Provides a [TimelineItemPresenterFactories] to the composition.
+ */
+val LocalTimelineItemPresenterFactories = staticCompositionLocalOf {
+    TimelineItemPresenterFactories(emptyMap())
+}
+
+/**
+ * Creates and remembers a presenter for the given content.
+ *
+ * Will throw if the presenter is not found in the [TimelineItemPresenterFactory] map multi binding.
+ */
+@Composable
+inline fun <reified C : TimelineItemEventContent, reified S : Any> TimelineItemPresenterFactories.rememberPresenter(
+    content: C
+): Presenter<S> = remember(content) {
+    factories.getValue(C::class.java).let {
+        @Suppress("UNCHECKED_CAST")
+        (it as TimelineItemPresenterFactory<C, S>).create(content)
+    }
+}

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

@@ -0,0 +1,33 @@
+/*
+ * 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.features.messages.impl.timeline.di
+
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEventContent
+import io.element.android.libraries.architecture.Presenter
+
+/**
+ * A factory for a [Presenter] associated with a timeline item.
+ *
+ * Implementations should be annotated with [AssistedFactory] to be created by Dagger.
+ *
+ * @param C The timeline item's [TimelineItemEventContent] subtype.
+ * @param S The [Presenter]'s state class.
+ * @return A [Presenter] that produces a state of type [S] for the given content of type [C].
+ */
+fun interface TimelineItemPresenterFactory<C : TimelineItemEventContent, S : Any> {
+    fun create(content: C): Presenter<S>
+}

tools/detekt/detekt.yml

@@ -219,7 +219,7 @@ Compose:
   CompositionLocalAllowlist:
     active: true
     # You can optionally define a list of CompositionLocals that are allowed here
-    allowedCompositionLocals: LocalCompoundColors, LocalSnackbarDispatcher, LocalCameraPositionState
+    allowedCompositionLocals: LocalCompoundColors, LocalSnackbarDispatcher, LocalCameraPositionState, LocalTimelineItemPresenterFactories
   CompositionLocalNaming:
     active: true
   ContentEmitterReturningValues: