Add suggestion of users when starting a Chat #2634

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

@@ -82,6 +82,12 @@ interface MatrixRoom : Closeable {
      */
     suspend fun updateMembers()
 
+    /**
+     * Get the members of the room. Note: generally this should not be used, please use
+     * [membersStateFlow] and [updateMembers] instead.
+     */
+    suspend fun getMembers(limit: Int = 5): Result<List<RoomMember>>
+
     /**
      * Will return an updated member or an error.
      */

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

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2024 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 io.element.android.libraries.matrix.api.room.recent
+
+import io.element.android.libraries.matrix.api.MatrixClient
+import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.libraries.matrix.api.core.UserId
+import io.element.android.libraries.matrix.api.room.CurrentUserMembership
+import io.element.android.libraries.matrix.api.room.MatrixRoom
+import io.element.android.libraries.matrix.api.room.toMatrixUser
+import io.element.android.libraries.matrix.api.user.MatrixUser
+import kotlinx.coroutines.flow.first
+
+private const val MAX_RECENT_DIRECT_ROOMS_TO_RETURN = 5
+
+data class RecentDirectRoom(
+    val roomId: RoomId,
+    val matrixUser: MatrixUser,
+)
+
+suspend fun MatrixClient.getRecentDirectRooms(
+    maxNumberOfResults: Int = MAX_RECENT_DIRECT_ROOMS_TO_RETURN,
+): List<RecentDirectRoom> {
+    val result = mutableListOf<RecentDirectRoom>()
+    val foundUserIds = mutableSetOf<UserId>()
+    getRecentlyVisitedRooms().getOrNull()?.let { roomIds ->
+        roomIds
+            .mapNotNull { roomId -> getRoom(roomId) }
+            .filter { it.isDm && it.isJoined() }
+            .map { room ->
+                val otherUser = room.getMembers().getOrNull()
+                    ?.firstOrNull { it.userId != sessionId }
+                    ?.takeIf { foundUserIds.add(it.userId) }
+                    ?.toMatrixUser()
+                if (otherUser != null) {
+                    result.add(
+                        RecentDirectRoom(room.roomId, otherUser)
+                    )
+                    // Return early to avoid useless computation
+                    if (result.size >= maxNumberOfResults) {
+                        return@map
+                    }
+                }
+            }
+    }
+    return result
+}
+
+suspend fun MatrixRoom.isJoined(): Boolean {
+    return roomInfoFlow.first().currentUserMembership == CurrentUserMembership.JOINED
+}