Read marker: handle the jump to read marker

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultGetContextOfEventTask.kt

@@ -26,7 +26,8 @@ internal interface GetContextOfEventTask : Task<GetContextOfEventTask.Params, To
 
     data class Params(
             val roomId: String,
-            val eventId: String
+            val eventId: String,
+            val limit: Int
     )
 }
 
@@ -38,7 +39,7 @@ internal class DefaultGetContextOfEventTask @Inject constructor(private val room
     override suspend fun execute(params: GetContextOfEventTask.Params): TokenChunkEventPersistor.Result {
         val filter = filterRepository.getRoomFilter()
         val response = executeRequest<EventContextResponse> {
-            apiCall = roomAPI.getContextOfEvent(params.roomId, params.eventId, 0, filter)
+            apiCall = roomAPI.getContextOfEvent(params.roomId, params.eventId, params.limit, filter)
         }
         return tokenChunkEventPersistor.insertInDb(response, params.roomId, PaginationDirection.BACKWARDS)
     }

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt

@@ -633,7 +633,7 @@ internal class DefaultTimeline(
     }
 
     private fun fetchEvent(eventId: String) {
-        val params = GetContextOfEventTask.Params(roomId, eventId)
+        val params = GetContextOfEventTask.Params(roomId, eventId, settings.initialSize)
         cancelableBag += contextOfEventTask.configureWith(params).executeBy(taskExecutor)
     }
 

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/EventContextResponse.kt

@@ -30,6 +30,7 @@ data class EventContextResponse(
         @Json(name = "state") override val stateEvents: List<Event> = emptyList()
 ) : TokenChunkEvent {
 
-    override val events: List<Event>
+    override val events: List<Event> by lazy {
-        get() = listOf(event)
+        eventsAfter.reversed() + listOf(event) + eventsBefore
+    }
 }

vector/src/main/java/im/vector/riotx/features/home/room/detail/RoomDetailFragment.kt

@@ -474,7 +474,8 @@ class RoomDetailFragment @Inject constructor(
             it.dispatchTo(stateRestorer)
             it.dispatchTo(scrollOnNewMessageCallback)
             it.dispatchTo(scrollOnHighlightedEventCallback)
-            checkJumpToUnreadBanner()
+            updateJumpToReadMarkerViewVisibility()
+            updateJumpToBottomViewVisibility()
         }
         recyclerView.adapter = timelineEventController.adapter
 
@@ -520,19 +521,24 @@ class RoomDetailFragment @Inject constructor(
         }
     }
 
-    private fun checkJumpToUnreadBanner() = jumpToReadMarkerView.post {
+    private fun updateJumpToReadMarkerViewVisibility() = jumpToReadMarkerView.post {
         withState(roomDetailViewModel) {
             val showJumpToUnreadBanner = when (it.unreadState) {
                 UnreadState.Unknown,
                 UnreadState.HasNoUnread            -> false
+                is UnreadState.ReadMarkerNotLoaded -> true
                 is UnreadState.HasUnread           -> {
+                    if (it.canShowJumpToReadMarker) {
                         val lastVisibleItem = layoutManager.findLastVisibleItemPosition()
                         val positionOfReadMarker = timelineEventController.getPositionOfReadMarker()
                         if (positionOfReadMarker == null) {
-                        it.timeline?.isLive == true && lastVisibleItem > 0
+                            false
                         } else {
                             positionOfReadMarker > lastVisibleItem
                         }
+                    } else {
+                        false
+                    }
                 }
             }
             jumpToReadMarkerView.isVisible = showJumpToUnreadBanner
@@ -1031,14 +1037,10 @@ class RoomDetailFragment @Inject constructor(
     }
 
     override fun onReadMarkerVisible() {
-        checkJumpToUnreadBanner()
+        updateJumpToReadMarkerViewVisibility()
         roomDetailViewModel.handle(RoomDetailAction.EnterTrackingUnreadMessagesState)
     }
 
-    override fun onReadMarkerInvisible() {
-        checkJumpToUnreadBanner()
-    }
-
     // AutocompleteUserPresenter.Callback
 
     override fun onQueryUsers(query: CharSequence?) {
@@ -1244,8 +1246,12 @@ class RoomDetailFragment @Inject constructor(
     // JumpToReadMarkerView.Callback
 
     override fun onJumpToReadMarkerClicked() = withState(roomDetailViewModel) {
+        jumpToReadMarkerView.isVisible = false
         if (it.unreadState is UnreadState.HasUnread) {
-            roomDetailViewModel.handle(RoomDetailAction.NavigateToEvent(it.unreadState.eventId, false))
+            roomDetailViewModel.handle(RoomDetailAction.NavigateToEvent(it.unreadState.firstUnreadEventId, false))
+        }
+        if (it.unreadState is UnreadState.ReadMarkerNotLoaded) {
+            roomDetailViewModel.handle(RoomDetailAction.NavigateToEvent(it.unreadState.readMarkerId, false))
         }
     }
 

vector/src/main/java/im/vector/riotx/features/home/room/detail/RoomDetailViewModel.kt

@@ -65,6 +65,7 @@ import im.vector.riotx.features.settings.VectorPreferences
 import io.reactivex.Observable
 import io.reactivex.functions.BiFunction
 import io.reactivex.rxkotlin.subscribeBy
+import io.reactivex.schedulers.Schedulers
 import org.commonmark.parser.Parser
 import org.commonmark.renderer.html.HtmlRenderer
 import timber.log.Timber
@@ -179,6 +180,7 @@ class RoomDetailViewModel @AssistedInject constructor(@Assisted initialState: Ro
 
     private fun startTrackingUnreadMessages() {
         trackUnreadMessages.set(true)
+        setState { copy(canShowJumpToReadMarker = false) }
     }
 
     private fun stopTrackingUnreadMessages() {
@@ -188,6 +190,7 @@ class RoomDetailViewModel @AssistedInject constructor(@Assisted initialState: Ro
             }
             mostRecentDisplayedEvent = null
         }
+        setState { copy(canShowJumpToReadMarker = true) }
     }
 
     private fun handleEventInvisible(action: RoomDetailAction.TimelineEventTurnsInvisible) {
@@ -788,29 +791,33 @@ class RoomDetailViewModel @AssistedInject constructor(@Assisted initialState: Ro
     private fun getUnreadState() {
         Observable
                 .combineLatest<List<TimelineEvent>, RoomSummary, UnreadState>(
-                        timelineEvents,
+                        timelineEvents.observeOn(Schedulers.computation()),
                         room.rx().liveRoomSummary().unwrap(),
                         BiFunction { timelineEvents, roomSummary ->
                             computeUnreadState(timelineEvents, roomSummary)
                         }
                 )
-                .takeUntil {
+                // We don't want live update of unread so we skip when we already had a HasUnread or HasNoUnread
-                    it != UnreadState.Unknown
+                .distinctUntilChanged { previous, current ->
+                    when {
+                        previous is UnreadState.Unknown || previous is UnreadState.ReadMarkerNotLoaded -> false
+                        current is UnreadState.HasUnread || current is UnreadState.HasNoUnread         -> true
+                        else                                                                           -> false
                     }
-                .subscribe { unreadState ->
-                    setState {
-                        copy(unreadState = unreadState)
                 }
+                .subscribe {
+                    setState { copy(unreadState = it) }
                 }
                 .disposeOnClear()
     }
 
     private fun computeUnreadState(events: List<TimelineEvent>, roomSummary: RoomSummary): UnreadState {
+        if (events.isEmpty()) return UnreadState.Unknown
         val readMarkerIdSnapshot = roomSummary.readMarkerId ?: return UnreadState.Unknown
         val firstDisplayableEventId = timeline.getFirstDisplayableEventId(readMarkerIdSnapshot)
-                                      ?: return UnreadState.Unknown
+                ?: return UnreadState.ReadMarkerNotLoaded(readMarkerIdSnapshot)
         val firstDisplayableEventIndex = timeline.getIndexOfEvent(firstDisplayableEventId)
-                                         ?: return UnreadState.Unknown
+                ?: return UnreadState.ReadMarkerNotLoaded(readMarkerIdSnapshot)
         for (i in (firstDisplayableEventIndex - 1) downTo 0) {
             val timelineEvent = events.getOrNull(i) ?: return UnreadState.Unknown
             val eventId = timelineEvent.root.eventId ?: return UnreadState.Unknown
@@ -849,7 +856,6 @@ class RoomDetailViewModel @AssistedInject constructor(@Assisted initialState: Ro
 
     override fun onUpdated(snapshot: List<TimelineEvent>) {
         timelineEvents.accept(snapshot)
-        setState { copy(currentSnapshot = snapshot) }
     }
 
     override fun onCleared() {

vector/src/main/java/im/vector/riotx/features/home/room/detail/RoomDetailViewState.kt

@@ -44,7 +44,8 @@ sealed class SendMode(open val text: String) {
 sealed class UnreadState {
     object Unknown : UnreadState()
     object HasNoUnread : UnreadState()
-    data class HasUnread(val eventId: String) : UnreadState()
+    data class ReadMarkerNotLoaded(val readMarkerId: String): UnreadState()
+    data class HasUnread(val firstUnreadEventId: String) : UnreadState()
 }
 
 data class RoomDetailViewState(
@@ -59,10 +60,8 @@ data class RoomDetailViewState(
         val tombstoneEventHandling: Async<String> = Uninitialized,
         val syncState: SyncState = SyncState.IDLE,
         val highlightedEventId: String? = null,
-        val currentSnapshot: List<TimelineEvent> = emptyList(),
+        val unreadState: UnreadState = UnreadState.Unknown,
-        val hasMoreToLoadForward: Boolean = false,
+        val canShowJumpToReadMarker: Boolean = true
-        val hasMoreToLoadBackward: Boolean = false,
-        val unreadState: UnreadState = UnreadState.Unknown
 ) : MvRxState {
 
     constructor(args: RoomDetailArgs) : this(roomId = args.roomId, eventId = args.eventId)

vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/TimelineEventController.kt

@@ -83,7 +83,6 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
     interface ReadReceiptsCallback {
         fun onReadReceiptsClicked(readReceipts: List<ReadReceiptData>)
         fun onReadMarkerVisible()
-        fun onReadMarkerInvisible()
     }
 
     interface UrlClickCallback {
@@ -297,7 +296,7 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
     private fun buildReadMarkerItem(event: TimelineEvent, currentUnreadState: UnreadState): TimelineReadMarkerItem? {
         return when (currentUnreadState) {
             is UnreadState.HasUnread -> {
-                if (event.root.eventId == currentUnreadState.eventId) {
+                if (event.root.eventId == currentUnreadState.firstUnreadEventId) {
                     TimelineReadMarkerItem_()
                             .also {
                                 it.id("read_marker")
@@ -307,8 +306,7 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
                     null
                 }
             }
-            UnreadState.Unknown,
+            else                     -> null
-            UnreadState.HasNoUnread  -> null
         }
     }
 
@@ -359,6 +357,11 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
             val formattedDayModel: DaySeparatorItem? = null,
             val readMarkerModel: TimelineReadMarkerItem? = null
     ) {
-        fun shouldTriggerBuild(unreadState: UnreadState) = mergedHeaderModel != null || formattedDayModel != null || readMarkerModel != null || (unreadState is UnreadState.HasUnread && unreadState.eventId == eventId)
+        fun shouldTriggerBuild(unreadState: UnreadState): Boolean {
+            return mergedHeaderModel != null
+                    || formattedDayModel != null
+                    || readMarkerModel != null
+                    || (unreadState is UnreadState.HasUnread && unreadState.firstUnreadEventId == eventId)
+        }
     }
 }

vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/helper/TimelineVisibilityStateChangedListeners.kt

@@ -27,8 +27,6 @@ class ReadMarkerVisibilityStateChangedListener(private val callback: TimelineEve
     override fun onVisibilityStateChanged(visibilityState: Int) {
         if (visibilityState == VisibilityState.VISIBLE) {
             callback?.onReadMarkerVisible()
-        } else if (visibilityState == VisibilityState.INVISIBLE) {
-            callback?.onReadMarkerInvisible()
         }
     }
 }