Add better support for empty room name fallback

CHANGES.md

@@ -14,6 +14,7 @@ Improvements 🙌:
  - Update reactions to Unicode 13.1 (#2998)
  - Be more robust when parsing some enums
  - Improve timeline filtering (dissociate membership and profile events, display hidden events when highlighted, fix hidden item/read receipts behavior)
+ - Add better support for empty room name fallback (#3106)
 
 Bugfix 🐛:
  - Fix bad theme change for the MainActivity

matrix-sdk-android/src/androidTest/java/org/matrix/android/sdk/common/TestRoomDisplayNameFallbackProvider.kt

@@ -18,12 +18,12 @@ package org.matrix.android.sdk.common
 
 import org.matrix.android.sdk.api.RoomDisplayNameFallbackProvider
 
-class TestRoomDisplayNameFallbackProvider() : RoomDisplayNameFallbackProvider {
+class TestRoomDisplayNameFallbackProvider : RoomDisplayNameFallbackProvider {
 
     override fun getNameForRoomInvite() =
             "Room invite"
 
-    override fun getNameForEmptyRoom() =
+    override fun getNameForEmptyRoom(isDirect: Boolean, leftMemberNames: List<String>) =
             "Empty room"
 
     override fun getNameFor2members(name1: String?, name2: String?) =

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/RoomDisplayNameFallbackProvider.kt

@@ -18,7 +18,7 @@ package org.matrix.android.sdk.api
 
 interface RoomDisplayNameFallbackProvider {
     fun getNameForRoomInvite(): String
-    fun getNameForEmptyRoom(): String
+    fun getNameForEmptyRoom(isDirect: Boolean, leftMemberNames: List<String>): String
     fun getNameFor2members(name1: String?, name2: String?): String
     fun getNameFor3members(name1: String?, name2: String?, name3: String?): String
     fun getNameFor4members(name1: String?, name2: String?, name3: String?, name4: String?): String

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/membership/RoomDisplayNameResolver.kt

@@ -18,6 +18,7 @@ package org.matrix.android.sdk.internal.session.room.membership
 
 import io.realm.Realm
 import org.matrix.android.sdk.api.MatrixConfiguration
+import org.matrix.android.sdk.api.extensions.orFalse
 import org.matrix.android.sdk.api.session.events.model.EventType
 import org.matrix.android.sdk.api.session.events.model.toModel
 import org.matrix.android.sdk.api.session.room.model.Membership
@@ -51,14 +52,14 @@ internal class RoomDisplayNameResolver @Inject constructor(
      * @param roomId: the roomId to resolve the name of.
      * @return the room display name
      */
-    fun resolve(realm: Realm, roomId: String): CharSequence {
+    fun resolve(realm: Realm, roomId: String): String {
         // this algorithm is the one defined in
         // https://github.com/matrix-org/matrix-js-sdk/blob/develop/lib/models/room.js#L617
         // calculateRoomName(room, userId)
 
         // For Lazy Loaded room, see algorithm here:
         // https://docs.google.com/document/d/11i14UI1cUz-OJ0knD5BFu7fmT6Fo327zvMYqfSAR7xs/edit#heading=h.qif6pkqyjgzn
-        var name: CharSequence?
+        var name: String?
         val roomEntity = RoomEntity.where(realm, roomId = roomId).findFirst()
         val roomName = CurrentStateEventEntity.getOrNull(realm, roomId, type = EventType.STATE_ROOM_NAME, stateKey = "")?.root
         name = ContentMapper.map(roomName?.content).toModel<RoomNameContent>()?.name
@@ -105,8 +106,12 @@ internal class RoomDisplayNameResolver @Inject constructor(
             val otherMembersCount = otherMembersSubset.count()
             name = when (otherMembersCount) {
                 0    -> {
-                    roomDisplayNameFallbackProvider.getNameForEmptyRoom()
+                    // Get left members if any
-                    // TODO (was xx and yyy) ...
+                    val leftMembersNames = roomMembers.queryRoomMembersEvent()
+                            .findAll()
+                            .filter { it.membership == Membership.LEAVE }
+                            .map { it.getBestName() }
+                    roomDisplayNameFallbackProvider.getNameForEmptyRoom(roomSummary?.isDirect.orFalse(), leftMembersNames)
                 }
                 1    -> resolveRoomMemberName(otherMembersSubset[0], roomMembers)
                 2    -> {

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/summary/RoomSummaryUpdater.kt

@@ -102,7 +102,7 @@ internal class RoomSummaryUpdater @Inject constructor(
                 // avoid this call if we are sure there are unread events
                 || !isEventRead(realm.configuration, userId, roomId, latestPreviewableEvent?.eventId)
 
-        roomSummaryEntity.displayName = roomDisplayNameResolver.resolve(realm, roomId).toString()
+        roomSummaryEntity.displayName = roomDisplayNameResolver.resolve(realm, roomId)
         roomSummaryEntity.avatarUrl = roomAvatarResolver.resolve(realm, roomId)
         roomSummaryEntity.name = ContentMapper.map(lastNameEvent?.content).toModel<RoomNameContent>()?.name
         roomSummaryEntity.topic = ContentMapper.map(lastTopicEvent?.content).toModel<RoomTopicContent>()?.topic

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/UserAccountDataSyncHandler.kt

@@ -46,6 +46,7 @@ import org.matrix.android.sdk.internal.database.query.where
 import org.matrix.android.sdk.internal.di.SessionDatabase
 import org.matrix.android.sdk.internal.di.UserId
 import org.matrix.android.sdk.internal.session.room.RoomAvatarResolver
+import org.matrix.android.sdk.internal.session.room.membership.RoomDisplayNameResolver
 import org.matrix.android.sdk.internal.session.room.membership.RoomMemberHelper
 import org.matrix.android.sdk.internal.session.sync.model.InvitedRoomSync
 import org.matrix.android.sdk.internal.session.sync.model.accountdata.BreadcrumbsContent
@@ -62,7 +63,8 @@ internal class UserAccountDataSyncHandler @Inject constructor(
         @UserId private val userId: String,
         private val directChatsHelper: DirectChatsHelper,
         private val updateUserAccountDataTask: UpdateUserAccountDataTask,
-        private val roomAvatarResolver: RoomAvatarResolver
+        private val roomAvatarResolver: RoomAvatarResolver,
+        private val roomDisplayNameResolver: RoomDisplayNameResolver
 ) {
 
     fun handle(realm: Realm, accountData: UserAccountDataSync?) {
@@ -161,8 +163,9 @@ internal class UserAccountDataSyncHandler @Inject constructor(
                 if (roomSummaryEntity != null) {
                     roomSummaryEntity.isDirect = true
                     roomSummaryEntity.directUserId = userId
-                    // Also update the avatar, there is a specific treatment for DMs
+                    // Also update the avatar and displayname, there is a specific treatment for DMs
                     roomSummaryEntity.avatarUrl = roomAvatarResolver.resolve(realm, roomId)
+                    roomSummaryEntity.displayName = roomDisplayNameResolver.resolve(realm, roomId)
                 }
             }
         }
@@ -172,8 +175,9 @@ internal class UserAccountDataSyncHandler @Inject constructor(
                 .forEach {
                     it.isDirect = false
                     it.directUserId = null
-                    // Also update the avatar, there was a specific treatment for DMs
+                    // Also update the avatar and displayname, there was a specific treatment for DMs
                     it.avatarUrl = roomAvatarResolver.resolve(realm, it.roomId)
+                    it.displayName = roomDisplayNameResolver.resolve(realm, it.roomId)
                 }
     }
 

vector/src/main/java/im/vector/app/features/room/VectorRoomDisplayNameFallbackProvider.kt

@@ -28,8 +28,12 @@ class VectorRoomDisplayNameFallbackProvider(
         return context.getString(R.string.room_displayname_room_invite)
     }
 
-    override fun getNameForEmptyRoom(): String {
+    override fun getNameForEmptyRoom(isDirect: Boolean, leftMemberNames: List<String>): String {
-        return context.getString(R.string.room_displayname_empty_room)
+        return if (leftMemberNames.isEmpty()) {
+            context.getString(R.string.room_displayname_empty_room)
+        } else {
+            context.getString(R.string.room_displayname_empty_room_was, leftMemberNames.joinToString())
+        }
     }
 
     override fun getNameFor2members(name1: String?, name2: String?): String {