Fix pinned events banner reappearing when loading (#3519)

* Fix pinned events banner reappearing when loading.

Make the `RustTimelineItem.timelineItems` property a `SharedFlow` so we don't always incorrectly load an empty state by default.

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/pinned/banner/PinnedMessagesBannerPresenter.kt

@@ -24,7 +24,6 @@ import io.element.android.libraries.matrix.api.room.MatrixRoom
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.toImmutableList
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.flow.launchIn
@@ -106,7 +105,7 @@ class PinnedMessagesBannerPresenter @Inject constructor(
         }
     }
 
-    @OptIn(FlowPreview::class, ExperimentalCoroutinesApi::class)
+    @OptIn(ExperimentalCoroutinesApi::class)
     @Composable
     private fun PinnedMessagesBannerItemsEffect(
         onItemsChange: (AsyncData<ImmutableList<PinnedMessagesBannerItem>>) -> Unit,

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/pinned/list/PinnedMessagesListPresenter.kt

@@ -41,7 +41,6 @@ import io.element.android.libraries.matrix.api.room.roomMembers
 import io.element.android.libraries.ui.strings.CommonStrings
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.flow.launchIn
@@ -161,7 +160,6 @@ class PinnedMessagesListPresenter @AssistedInject constructor(
         }
     }
 
-    @OptIn(FlowPreview::class)
     @Composable
     private fun PinnedMessagesListEffect(onItemsChange: (AsyncData<ImmutableList<TimelineItem>>) -> Unit) {
         val updatedOnItemsChange by rememberUpdatedState(onItemsChange)

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

@@ -11,7 +11,7 @@ import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
 import io.element.android.libraries.matrix.api.timeline.item.event.RoomMembershipContent
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
-import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import org.matrix.rustcomponents.sdk.TimelineChange
@@ -20,7 +20,7 @@ import org.matrix.rustcomponents.sdk.TimelineItem
 import timber.log.Timber
 
 internal class MatrixTimelineDiffProcessor(
-    private val timelineItems: MutableStateFlow<List<MatrixTimelineItem>>,
+    private val timelineItems: MutableSharedFlow<List<MatrixTimelineItem>>,
     private val timelineItemFactory: MatrixTimelineItemMapper,
 ) {
     private val mutex = Mutex()
@@ -47,9 +47,13 @@ internal class MatrixTimelineDiffProcessor(
 
     private suspend fun updateTimelineItems(block: MutableList<MatrixTimelineItem>.() -> Unit) =
         mutex.withLock {
-            val mutableTimelineItems = timelineItems.value.toMutableList()
+            val mutableTimelineItems = if (timelineItems.replayCache.isNotEmpty()) {
+                timelineItems.first().toMutableList()
+            } else {
+                mutableListOf()
+            }
             block(mutableTimelineItems)
-            timelineItems.value = mutableTimelineItems
+            timelineItems.tryEmit(mutableTimelineItems)
         }
 
     private fun MutableList<MatrixTimelineItem>.applyDiff(diff: TimelineDiff) {

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

@@ -49,10 +49,12 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.NonCancellable
 import kotlinx.coroutines.cancel
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.getAndUpdate
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.map
@@ -88,8 +90,8 @@ class RustTimeline(
     private val initLatch = CompletableDeferred<Unit>()
     private val isTimelineInitialized = MutableStateFlow(false)
 
-    private val _timelineItems: MutableStateFlow<List<MatrixTimelineItem>> =
+    private val _timelineItems: MutableSharedFlow<List<MatrixTimelineItem>> =
-        MutableStateFlow(emptyList())
+        MutableSharedFlow(replay = 1, extraBufferCapacity = Int.MAX_VALUE)
 
     private val timelineEventContentMapper = TimelineEventContentMapper()
     private val inReplyToMapper = InReplyToMapper(timelineEventContentMapper)
@@ -522,7 +524,7 @@ class RustTimeline(
     }
 
     override suspend fun loadReplyDetails(eventId: EventId): InReplyTo = withContext(dispatcher) {
-        val timelineItem = _timelineItems.value.firstOrNull { timelineItem ->
+        val timelineItem = _timelineItems.first().firstOrNull { timelineItem ->
             timelineItem is MatrixTimelineItem.Event && timelineItem.eventId == eventId
         } as? MatrixTimelineItem.Event