[ContactList] Add functions

lib/src/Client.dart

@@ -219,6 +219,18 @@ class Client {
         type: HTTPType.POST, action: "/client/r0/join/$id");
   }
 
+  /// Loads the contact list for this user excluding the users in
+  /// the given room of id [exceptRoomID] and the user itself. Currently the contacts are
+  /// found by discovering the contacts of the famedlyContactDiscovery room, which is
+  /// defined by the autojoin room feature in Synapse.
+  Future<List<User>> loadFamedlyContacts({String exceptRoomID = ""}) async {
+    Room contactDiscoveryRoom = await store
+        .getRoomByAlias("#famedlyContactDiscovery:${userID.split(":")[1]}");
+    List<User> contacts = await contactDiscoveryRoom.requestParticipants();
+
+    return contacts;
+  }
+
   /// Creates a new group chat and invites the given Users and returns the new
   /// created room ID.
   Future<String> createGroup(List<User> users) async {

lib/src/Store.dart

@@ -458,6 +458,7 @@ class Store {
 
   /// Loads all Users in the database to provide a contact list
   /// except users who are in the Room with the ID [exceptRoomID].
+  @deprecated
   Future<List<User>> loadContacts({String exceptRoomID = ""}) async {
     List<Map<String, dynamic>> res = await db.rawQuery(
         "SELECT * FROM Users WHERE matrix_id!=? AND chat_id!=? GROUP BY matrix_id ORDER BY displayname",
@@ -549,6 +550,14 @@ class Store {
     return Room.getRoomFromTableRow(res[0], client);
   }
 
+  /// Returns a room without events and participants.
+  Future<Room> getRoomByAlias(String alias) async {
+    List<Map<String, dynamic>> res = await db
+        .rawQuery("SELECT * FROM Rooms WHERE canonical_alias=?", [alias]);
+    if (res.length != 1) return null;
+    return Room.getRoomFromTableRow(res[0], client);
+  }
+
   /// Calculates and returns an avatar for a direct chat by a given [roomID].
   Future<String> getAvatarFromSingleChat(String roomID) async {
     String avatarStr = "";