[Room member list] Display room member list (#276)

* Implement room member list

* Move timeline initialization back to `TimelinePresenter`.

* Fix crash when the `innerRoom` inside a `RustMatrixRoom` is destroyed but `syncUpdateFlow` is still running.

* Address review comments

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt

@@ -31,9 +31,11 @@ interface MatrixRoom: Closeable {
     val alternativeAliases: List<String>
     val topic: String?
     val avatarUrl: String?
-    val members: List<RoomMember>
     val isEncrypted: Boolean
 
+    suspend fun members() : List<RoomMember>
+    suspend fun memberCount(): Int
+
     fun syncUpdateFlow(): Flow<Long>
 
     fun timeline(): MatrixTimeline

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/room/RustMatrixRoom.kt

@@ -17,6 +17,7 @@
 package io.element.android.libraries.matrix.impl.room
 
 import io.element.android.libraries.core.coroutine.CoroutineDispatchers
+import io.element.android.libraries.core.data.tryOrNull
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.RoomId
 import io.element.android.libraries.matrix.api.room.MatrixRoom
@@ -24,10 +25,12 @@ import io.element.android.libraries.matrix.api.room.RoomMember
 import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
 import io.element.android.libraries.matrix.impl.timeline.RustMatrixTimeline
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onStart
+import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import org.matrix.rustcomponents.sdk.Room
 import org.matrix.rustcomponents.sdk.SlidingSyncRoom
@@ -43,10 +46,32 @@ class RustMatrixRoom(
     private val coroutineDispatchers: CoroutineDispatchers,
 ) : MatrixRoom {
 
+    private var loadMembersJob: Job? = null
+    private var cachedMembers: List<RoomMember> = emptyList()
+
+    override suspend fun members(): List<RoomMember> {
+        return cachedMembers.ifEmpty {
+            if (loadMembersJob == null) {
+                loadMembersJob = coroutineScope.launch(coroutineDispatchers.io) {
+                    cachedMembers = tryOrNull {
+                        innerRoom.members().map(RoomMemberMapper::map)
+                    } ?: emptyList()
+                }
+            }
+            loadMembersJob?.join()
+            loadMembersJob = null
+            cachedMembers
+        }
+    }
+
+    override suspend fun memberCount(): Int {
+        return members().size
+    }
+
     override fun syncUpdateFlow(): Flow<Long> {
         return slidingSyncUpdateFlow
             .filter {
-                it.rooms.contains(innerRoom.id())
+                it.rooms.contains(roomId.value)
             }
             .map {
                 System.currentTimeMillis()
@@ -95,9 +120,6 @@ class RustMatrixRoom(
             return innerRoom.avatarUrl()
         }
 
-    override val members: List<RoomMember>
-        get() = innerRoom.members().map(RoomMemberMapper::map)
-
     override val isEncrypted: Boolean
         get() = innerRoom.isEncrypted()
 

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

@@ -87,14 +87,6 @@ class RustMatrixTimeline(
 
     override fun initialize() {
         Timber.v("Init timeline for room ${matrixRoom.roomId}")
-        coroutineScope.launch {
-            matrixRoom.fetchMembers()
-                .onFailure {
-                    Timber.e(it, "Fail to fetch members for room ${matrixRoom.roomId}")
-                }.onSuccess {
-                    Timber.v("Success fetching members for room ${matrixRoom.roomId}")
-                }
-        }
         coroutineScope.launch {
             val result = addListener(innerTimelineListener)
             result

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt

@@ -34,13 +34,18 @@ class FakeMatrixRoom(
     override val displayName: String = "",
     override val topic: String? = null,
     override val avatarUrl: String? = null,
-    override val members: List<RoomMember> = emptyList(),
     override val isEncrypted: Boolean = false,
     override val alias: String? = null,
     override val alternativeAliases: List<String> = emptyList(),
+    private val members: List<RoomMember> = emptyList(),
     private val matrixTimeline: MatrixTimeline = FakeMatrixTimeline(),
 ) : MatrixRoom {
 
+    private var fetchMemberResult: Result<Unit> = Result.success(Unit)
+
+    var areMembersFetched: Boolean = false
+        private set
+
     override fun syncUpdateFlow(): Flow<Long> {
         return emptyFlow()
     }
@@ -50,7 +55,11 @@ class FakeMatrixRoom(
     }
 
     override suspend fun fetchMembers(): Result<Unit> {
-        return Result.success(Unit)
+        return fetchMemberResult.also { result ->
+            if (result.isSuccess) {
+                areMembersFetched = true
+            }
+        }
     }
 
     override suspend fun userDisplayName(userId: String): Result<String?> {
@@ -61,6 +70,18 @@ class FakeMatrixRoom(
         TODO("Not yet implemented")
     }
 
+    override suspend fun members(): List<RoomMember> {
+        return members
+    }
+
+    override suspend fun memberCount(): Int {
+        if (fetchMemberResult.isSuccess) {
+            return members.count()
+        } else {
+            throw fetchMemberResult.exceptionOrNull()!!
+        }
+    }
+
     override suspend fun sendMessage(message: String): Result<Unit> {
         delay(100)
         return Result.success(Unit)
@@ -94,4 +115,8 @@ class FakeMatrixRoom(
     }
 
     override fun close() = Unit
+
+    fun givenFetchMemberResult(result: Result<Unit>) {
+        fetchMemberResult = result
+    }
 }