VoiceBroadcastPlayer - Fetch playlist in dedicated use case and improve player

Author: Florian Renaud

vector/src/main/java/im/vector/app/features/voicebroadcast/listening/VoiceBroadcastPlayerImpl.kt

@@ -23,53 +23,42 @@ import im.vector.app.core.di.ActiveSessionHolder
 import im.vector.app.features.home.room.detail.timeline.helper.AudioMessagePlaybackTracker
 import im.vector.app.features.voice.VoiceFailure
 import im.vector.app.features.voicebroadcast.getVoiceBroadcastChunk
-import im.vector.app.features.voicebroadcast.getVoiceBroadcastEventId
-import im.vector.app.features.voicebroadcast.isVoiceBroadcast
 import im.vector.app.features.voicebroadcast.listening.VoiceBroadcastPlayer.Listener
 import im.vector.app.features.voicebroadcast.listening.VoiceBroadcastPlayer.State
+import im.vector.app.features.voicebroadcast.listening.usecase.GetLiveVoiceBroadcastChunksUseCase
 import im.vector.app.features.voicebroadcast.model.VoiceBroadcastState
-import im.vector.app.features.voicebroadcast.model.asVoiceBroadcastEvent
 import im.vector.app.features.voicebroadcast.sequence
 import im.vector.app.features.voicebroadcast.usecase.GetVoiceBroadcastUseCase
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
-import org.matrix.android.sdk.api.session.events.model.RelationType
-import org.matrix.android.sdk.api.session.getRoom
-import org.matrix.android.sdk.api.session.room.Room
 import org.matrix.android.sdk.api.session.room.model.message.MessageAudioContent
 import org.matrix.android.sdk.api.session.room.model.message.MessageAudioEvent
-import org.matrix.android.sdk.api.session.room.model.message.asMessageAudioEvent
-import org.matrix.android.sdk.api.session.room.timeline.Timeline
-import org.matrix.android.sdk.api.session.room.timeline.TimelineEvent
-import org.matrix.android.sdk.api.session.room.timeline.TimelineSettings
 import timber.log.Timber
 import java.util.concurrent.CopyOnWriteArrayList
 import javax.inject.Inject
+import javax.inject.Singleton
 
 @Singleton
 class VoiceBroadcastPlayerImpl @Inject constructor(
         private val sessionHolder: ActiveSessionHolder,
         private val playbackTracker: AudioMessagePlaybackTracker,
         private val getVoiceBroadcastUseCase: GetVoiceBroadcastUseCase,
+        private val getLiveVoiceBroadcastChunksUseCase: GetLiveVoiceBroadcastChunksUseCase
 ) : VoiceBroadcastPlayer {
+
     private val session
         get() = sessionHolder.getActiveSession()
 
     private val coroutineScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
     private var voiceBroadcastStateJob: Job? = null
-    private var currentTimeline: Timeline? = null
-        set(value) {
-            field?.removeAllListeners()
-            field?.dispose()
-            field = value
-        }
 
     private val mediaPlayerListener = MediaPlayerListener()
-    private var timelineListener: TimelineListener? = null
 
     private var currentMediaPlayer: MediaPlayer? = null
     private var nextMediaPlayer: MediaPlayer? = null
@@ -79,7 +68,10 @@ class VoiceBroadcastPlayerImpl @Inject constructor(
         }
     private var currentSequence: Int? = null
 
+    private var fetchPlaylistJob: Job? = null
     private var playlist = emptyList<MessageAudioEvent>()
+    private var isLive: Boolean = false
+
     override var currentVoiceBroadcastId: String? = null
 
     override var playingState = State.IDLE
@@ -118,6 +110,7 @@ class VoiceBroadcastPlayerImpl @Inject constructor(
         // Stop playback
         currentMediaPlayer?.stop()
         currentVoiceBroadcastId?.let { playbackTracker.stopPlayback(it) }
+        isLive = false
 
         // Release current player
         release(currentMediaPlayer)
@@ -131,39 +124,33 @@ class VoiceBroadcastPlayerImpl @Inject constructor(
         voiceBroadcastStateJob?.cancel()
         voiceBroadcastStateJob = null
 
-        // In case of live broadcast, stop observing new chunks
-        currentTimeline = null
-        timelineListener = null
+        // Do not fetch the playlist anymore
+        fetchPlaylistJob?.cancel()
+        fetchPlaylistJob = null
 
         // Update state
         playingState = State.IDLE
 
         // Clear playlist
         playlist = emptyList()
         currentSequence = null
+
         currentRoomId = null
         currentVoiceBroadcastId = null
     }
 
-    /**
-     * Add a [Listener] to the given voice broadcast id.
-     */
     override fun addListener(voiceBroadcastId: String, listener: Listener) {
         listeners[voiceBroadcastId]?.add(listener) ?: run {
             listeners[voiceBroadcastId] = CopyOnWriteArrayList<Listener>().apply { add(listener) }
         }
         if (voiceBroadcastId == currentVoiceBroadcastId) listener.onStateChanged(playingState) else listener.onStateChanged(State.IDLE)
     }
 
-    /**
-     * Remove a [Listener] from the given voice broadcast id.
-     */
     override fun removeListener(voiceBroadcastId: String, listener: Listener) {
         listeners[voiceBroadcastId]?.remove(listener)
     }
 
     private fun startPlayback(roomId: String, eventId: String) {
-        val room = session.getRoom(roomId) ?: error("Unknown roomId: $roomId")
         // Stop listening previous voice broadcast if any
         if (playingState != State.IDLE) stop()
 
@@ -173,16 +160,11 @@ class VoiceBroadcastPlayerImpl @Inject constructor(
         playingState = State.BUFFERING
 
         val voiceBroadcastState = getVoiceBroadcastUseCase.execute(roomId, eventId)?.content?.voiceBroadcastState
-        if (voiceBroadcastState == VoiceBroadcastState.STOPPED) {
-            // Get static playlist
-            updatePlaylist(getExistingChunks(room, eventId))
-            startPlayback(false)
-        } else {
-            playLiveVoiceBroadcast(room, eventId)
-        }
+        isLive = voiceBroadcastState != null && voiceBroadcastState != VoiceBroadcastState.STOPPED
+        observeIncomingEvents(roomId, eventId)
     }
 
-    private fun startPlayback(isLive: Boolean) {
+    private fun startPlayback() {
         val event = if (isLive) playlist.lastOrNull() else playlist.firstOrNull()
         val content = event?.content ?: run { Timber.w("## VoiceBroadcastPlayer: No content to play"); return }
         val sequence = event.getVoiceBroadcastChunk()?.sequence
@@ -201,24 +183,10 @@ class VoiceBroadcastPlayerImpl @Inject constructor(
         }
     }
 
-    private fun playLiveVoiceBroadcast(room: Room, eventId: String) {
-        room.timelineService().getTimelineEvent(eventId)?.root?.asVoiceBroadcastEvent() ?: error("Cannot retrieve voice broadcast $eventId")
-        updatePlaylist(getExistingChunks(room, eventId))
-        startPlayback(true)
-        observeIncomingEvents(room, eventId)
-    }
-
-    private fun getExistingChunks(room: Room, eventId: String): List<MessageAudioEvent> {
-        return room.timelineService().getTimelineEventsRelatedTo(RelationType.REFERENCE, eventId)
-                .mapNotNull { it.root.asMessageAudioEvent() }
-                .filter { it.isVoiceBroadcast() }
-    }
-
-    private fun observeIncomingEvents(room: Room, eventId: String) {
-        currentTimeline = room.timelineService().createTimeline(null, TimelineSettings(5)).also { timeline ->
-            timelineListener = TimelineListener(eventId).also { timeline.addListener(it) }
-            timeline.start()
-        }
+    private fun observeIncomingEvents(roomId: String, voiceBroadcastId: String) {
+        fetchPlaylistJob = getLiveVoiceBroadcastChunksUseCase.execute(roomId, voiceBroadcastId)
+                .onEach(this::updatePlaylist)
+                .launchIn(coroutineScope)
     }
 
     private fun resumePlayback() {
@@ -229,11 +197,32 @@ class VoiceBroadcastPlayerImpl @Inject constructor(
 
     private fun updatePlaylist(playlist: List<MessageAudioEvent>) {
         this.playlist = playlist.sortedBy { it.getVoiceBroadcastChunk()?.sequence?.toLong() ?: it.root.originServerTs }
+        onPlaylistUpdated()
+    }
+
+    private fun onPlaylistUpdated() {
+        when (playingState) {
+            State.PLAYING -> {
+                if (nextMediaPlayer == null) {
+                    coroutineScope.launch { nextMediaPlayer = prepareNextMediaPlayer() }
+                }
+            }
+            State.PAUSED -> {
+                if (nextMediaPlayer == null) {
+                    coroutineScope.launch { nextMediaPlayer = prepareNextMediaPlayer() }
+                }
+            }
+            State.BUFFERING -> {
+                val newMediaContent = getNextAudioContent()
+                if (newMediaContent != null) startPlayback()
+            }
+            State.IDLE -> startPlayback()
+        }
     }
 
     private fun getNextAudioContent(): MessageAudioContent? {
         val nextSequence = currentSequence?.plus(1)
-                ?: timelineListener?.let { playlist.lastOrNull()?.sequence }
+                ?: playlist.lastOrNull()?.sequence
                 ?: 1
         return playlist.find { it.getVoiceBroadcastChunk()?.sequence == nextSequence }?.content
     }
@@ -279,37 +268,6 @@ class VoiceBroadcastPlayerImpl @Inject constructor(
         }
     }
 
-    private inner class TimelineListener(private val voiceBroadcastId: String) : Timeline.Listener {
-        override fun onTimelineUpdated(snapshot: List<TimelineEvent>) {
-            val currentSequences = playlist.map { it.sequence }
-            val newChunks = snapshot
-                    .mapNotNull { timelineEvent ->
-                        timelineEvent.root.asMessageAudioEvent()
-                                ?.takeIf { it.isVoiceBroadcast() && it.getVoiceBroadcastEventId() == voiceBroadcastId && it.sequence !in currentSequences }
-                    }
-            if (newChunks.isEmpty()) return
-            updatePlaylist(playlist + newChunks)
-
-            when (playingState) {
-                State.PLAYING -> {
-                    if (nextMediaPlayer == null) {
-                        coroutineScope.launch { nextMediaPlayer = prepareNextMediaPlayer() }
-                    }
-                }
-                State.PAUSED -> {
-                    if (nextMediaPlayer == null) {
-                        coroutineScope.launch { nextMediaPlayer = prepareNextMediaPlayer() }
-                    }
-                }
-                State.BUFFERING -> {
-                    val newMediaContent = getNextAudioContent()
-                    if (newMediaContent != null) startPlayback(true)
-                }
-                State.IDLE -> startPlayback(true)
-            }
-        }
-    }
-
     private inner class MediaPlayerListener : MediaPlayer.OnInfoListener, MediaPlayer.OnCompletionListener, MediaPlayer.OnErrorListener {
 
         override fun onInfo(mp: MediaPlayer, what: Int, extra: Int): Boolean {
@@ -329,7 +287,7 @@ class VoiceBroadcastPlayerImpl @Inject constructor(
             val roomId = currentRoomId ?: return
             val voiceBroadcastId = currentVoiceBroadcastId ?: return
             val voiceBroadcastEventContent = getVoiceBroadcastUseCase.execute(roomId, voiceBroadcastId)?.content ?: return
-            val isLive = voiceBroadcastEventContent.voiceBroadcastState != null && voiceBroadcastEventContent.voiceBroadcastState != VoiceBroadcastState.STOPPED
+            isLive = voiceBroadcastEventContent.voiceBroadcastState != null && voiceBroadcastEventContent.voiceBroadcastState != VoiceBroadcastState.STOPPED
 
             if (!isLive && voiceBroadcastEventContent.lastChunkSequence == currentSequence) {
                 // We'll not receive new chunks anymore so we can stop the live listening

vector/src/main/java/im/vector/app/features/voicebroadcast/listening/usecase/GetLiveVoiceBroadcastChunksUseCase.kt

@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 2022 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 im.vector.app.features.voicebroadcast.listening.usecase
+
+import im.vector.app.core.di.ActiveSessionHolder
+import im.vector.app.features.voicebroadcast.getVoiceBroadcastEventId
+import im.vector.app.features.voicebroadcast.isVoiceBroadcast
+import im.vector.app.features.voicebroadcast.model.VoiceBroadcastEvent
+import im.vector.app.features.voicebroadcast.model.VoiceBroadcastState
+import im.vector.app.features.voicebroadcast.model.asVoiceBroadcastEvent
+import im.vector.app.features.voicebroadcast.sequence
+import im.vector.app.features.voicebroadcast.usecase.GetVoiceBroadcastUseCase
+import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.emptyFlow
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.runningReduce
+import org.matrix.android.sdk.api.session.events.model.RelationType
+import org.matrix.android.sdk.api.session.room.model.message.MessageAudioEvent
+import org.matrix.android.sdk.api.session.room.model.message.asMessageAudioEvent
+import org.matrix.android.sdk.api.session.room.timeline.Timeline
+import org.matrix.android.sdk.api.session.room.timeline.TimelineEvent
+import org.matrix.android.sdk.api.session.room.timeline.TimelineSettings
+import javax.inject.Inject
+
+/**
+ * Get a [Flow] of [MessageAudioEvent]s related to the given voice broadcast.
+ */
+class GetLiveVoiceBroadcastChunksUseCase @Inject constructor(
+        private val activeSessionHolder: ActiveSessionHolder,
+        private val getVoiceBroadcastUseCase: GetVoiceBroadcastUseCase,
+) {
+
+    fun execute(roomId: String, voiceBroadcastId: String): Flow<List<MessageAudioEvent>> {
+        val session = activeSessionHolder.getSafeActiveSession() ?: return emptyFlow()
+        val room = session.roomService().getRoom(roomId) ?: return emptyFlow()
+        val timeline = room.timelineService().createTimeline(null, TimelineSettings(5))
+
+        // Get initial chunks
+        val existingChunks = room.timelineService().getTimelineEventsRelatedTo(RelationType.REFERENCE, voiceBroadcastId)
+                .mapNotNull { timelineEvent -> timelineEvent.root.asMessageAudioEvent().takeIf { it.isVoiceBroadcast() } }
+
+        val voiceBroadcastEvent = getVoiceBroadcastUseCase.execute(roomId, voiceBroadcastId)
+        val voiceBroadcastState = voiceBroadcastEvent?.content?.voiceBroadcastState
+
+        return if (voiceBroadcastState == null || voiceBroadcastState == VoiceBroadcastState.STOPPED) {
+            // Just send the existing chunks if voice broadcast is stopped
+            flowOf(existingChunks)
+        } else {
+            // Observe new timeline events if voice broadcast is ongoing
+            callbackFlow {
+                // Init with existing chunks
+                send(existingChunks)
+
+                // Observe new timeline events
+                val listener = object : Timeline.Listener {
+                    private var lastEventId: String? = null
+                    private var lastSequence: Int? = null
+
+                    override fun onTimelineUpdated(snapshot: List<TimelineEvent>) {
+                        val newEvents = lastEventId?.let { eventId -> snapshot.subList(0, snapshot.indexOfFirst { it.eventId == eventId }) } ?: snapshot
+
+                        // Detect a potential stopped voice broadcast state event
+                        val stopEvent = newEvents.findStopEvent()
+                        if (stopEvent != null) {
+                            lastSequence = stopEvent.content?.lastChunkSequence
+                        }
+
+                        val newChunks = newEvents.mapToChunkEvents(voiceBroadcastId, voiceBroadcastEvent.root.senderId)
+
+                        // Notify about new chunks
+                        if (newChunks.isNotEmpty()) {
+                            trySend(newChunks)
+                        }
+
+                        // Automatically stop observing the timeline if the last chunk has been received
+                        if (lastSequence != null && newChunks.any { it.sequence == lastSequence }) {
+                            timeline.removeListener(this)
+                            timeline.dispose()
+                        }
+
+                        lastEventId = snapshot.firstOrNull()?.eventId
+                    }
+                }
+
+                timeline.addListener(listener)
+                timeline.start()
+                awaitClose {
+                    timeline.removeListener(listener)
+                    timeline.dispose()
+                }
+            }
+                    .runningReduce { accumulator: List<MessageAudioEvent>, value: List<MessageAudioEvent> -> accumulator.plus(value) }
+        }
+    }
+
+    /**
+     * Find a [VoiceBroadcastEvent] with a [VoiceBroadcastState.STOPPED] state.
+     */
+    private fun List<TimelineEvent>.findStopEvent(): VoiceBroadcastEvent? =
+            this.mapNotNull { it.root.asVoiceBroadcastEvent() }
+                    .find { it.content?.voiceBroadcastState == VoiceBroadcastState.STOPPED }
+
+    /**
+     * Transform the list of [TimelineEvent] to a mapped list of [MessageAudioEvent] related to a given voice broadcast.
+     */
+    private fun List<TimelineEvent>.mapToChunkEvents(voiceBroadcastId: String, senderId: String?): List<MessageAudioEvent> =
+            this.mapNotNull { timelineEvent ->
+                timelineEvent.root.asMessageAudioEvent()
+                        ?.takeIf {
+                            it.isVoiceBroadcast() && it.getVoiceBroadcastEventId() == voiceBroadcastId &&
+                                    it.root.senderId == senderId
+                        }
+            }
+}