Get a ChatRoom object by its room id

app/src/main/java/chat/rocket/android/server/domain/GetChatRoomsInteractor.kt

 package chat.rocket.android.server.domain
 
 import chat.rocket.core.model.ChatRoom
+import kotlinx.coroutines.experimental.CommonPool
 import kotlinx.coroutines.experimental.async
 import javax.inject.Inject
 
@@ -19,4 +20,21 @@ class GetChatRoomsInteractor @Inject constructor(private val repository: ChatRoo
         }
         return chatRooms.await()
     }
+
+    /**
+     * Get a specific room by its id.
+     *
+     * @param serverUrl The server url where the room is.
+     * @param roomId The id of the room to get.
+     *
+     * @return The ChatRoom object or null if we couldn't find any.
+     */
+    suspend fun getByRoomId(serverUrl: String, roomId: String): ChatRoom {
+        return async(CommonPool) {
+            val allChatRooms = repository.get(serverUrl)
+            return@async allChatRooms.first {
+                it.id == roomId
+            }
+        }.await()
+    }
 }
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