Add support for participant attributes (#558)

* upgrade protocol to v1.19.1.

* Add Attributes for Participant.

* change attributes to UnmodifiableMapView.

* update ParticipantPermissions.

* dart run import_sorter:main.

* fix.

Author: cloudwebrtc

lib/src/events.dart

@@ -115,6 +115,21 @@ class RoomMetadataChangedEvent with RoomEvent {
   String toString() => '${runtimeType}()';
 }
 
+/// Participant's attributes have changed.
+/// Emitted by [Room].
+class ParticipantAttributesChanged with RoomEvent, ParticipantEvent {
+  final Participant participant;
+  final Map<String, String> attributes;
+
+  const ParticipantAttributesChanged({
+    required this.participant,
+    required this.attributes,
+  });
+
+  @override
+  String toString() => '${runtimeType}(participant: ${participant})';
+}
+
 /// Room recording status has changed.
 /// Emitted by [Room].
 class RoomRecordingStatusChanged with RoomEvent {

lib/src/participant/local.dart

@@ -466,6 +466,15 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
     ));
   }
 
+  /// Sets and updates the attributes of the local participant.
+  /// @attributes key-value pairs to set
+  void setAttributes(Map<String, String> attributes) {
+    room.engine.signalClient
+        .sendUpdateLocalMetadata(lk_rtc.UpdateParticipantMetadata(
+      attributes: attributes,
+    ));
+  }
+
   /// Sets and updates the name of the local participant.
   ///  Note: this requires `CanUpdateOwnMetadata` permission encoded in the token.
   ///  @param name

lib/src/participant/participant.dart

@@ -26,6 +26,7 @@ import '../publication/track_publication.dart';
 import '../support/disposable.dart';
 import '../types/other.dart';
 import '../types/participant_permissions.dart';
+import '../utils.dart';
 
 /// Represents a Participant in the room, notifies changes via delegates as
 /// well as ChangeNotifier/providers.
@@ -78,6 +79,11 @@ abstract class Participant<T extends TrackPublication>
   ParticipantPermissions _permissions = const ParticipantPermissions();
   ParticipantPermissions get permissions => _permissions;
 
+  /// Attributes associated with the participant
+  UnmodifiableMapView<String, String> get attributes =>
+      UnmodifiableMapView(_attributes);
+  Map<String, String> _attributes = {};
+
   /// when the participant joined the room
   DateTime get joinedAt {
     final pi = _participantInfo;
@@ -170,6 +176,18 @@ abstract class Participant<T extends TrackPublication>
     }
   }
 
+  void _setAttributes(Map<String, String> attrs) {
+    final diff = mapDiff(_attributes, attrs)
+        .map((k, v) => MapEntry(k as String, v as String));
+    _attributes = attrs;
+    if (diff.isNotEmpty) {
+      [
+        events,
+        room.events
+      ].emit(ParticipantAttributesChanged(participant: this, attributes: diff));
+    }
+  }
+
   @internal
   void updateConnectionQuality(ConnectionQuality quality) {
     if (_connectionQuality == quality) return;
@@ -196,6 +214,8 @@ abstract class Participant<T extends TrackPublication>
     if (info.metadata.isNotEmpty) {
       _setMetadata(info.metadata);
     }
+
+    _setAttributes(info.attributes);
     _participantInfo = info;
     setPermissions(info.permission.toLKType());