Retell Flutter Service

retell_service.dart

import 'package:livekit_client/livekit_client.dart' as livekit;
import 'package:permission_handler/permission_handler.dart';
import 'dart:async';

class RetellService {
  livekit.Room? _room;
  bool _connected = false;
  final StreamController<String> _eventStreamController =
      StreamController<String>.broadcast();

  Stream<String> get eventStream => _eventStreamController.stream;

  RetellService({required String accessToken}) {
    startCall(accessToken);
  }

  Future<void> startCall(String accessToken) async {
    _eventStreamController.add('Starting call');
    var status = await Permission.microphone.request();
    if (status != PermissionStatus.granted) {
      _eventStreamController.add('Microphone permission not granted');
      return;
    }

    try {
      _room = livekit.Room();
      await _room!.connect(
        'wss://retell-ai-4ihahnq7.livekit.cloud',
        accessToken,
        roomOptions: const livekit.RoomOptions(
          adaptiveStream: true,
          dynacast: true,
        ),
      );

      await _room!.localParticipant?.setMicrophoneEnabled(true);
      _connected = true;
      _eventStreamController.add('Connected to room: ${_room!.name}');

      _handleRoomEvents();
      _handleAudioEvents();
      _handleDataEvents();
    } catch (error) {
      _eventStreamController.add('Error starting call: $error');
      stopCall();
    }
  }

  void stopCall() {
    if (_connected) {
      _room?.disconnect();
      _connected = false;
      _eventStreamController.add('Call ended');
    }
  }

  void _handleRoomEvents() {
    _room?.addListener(() {
      if (_room?.connectionState == livekit.ConnectionState.disconnected) {
        stopCall();
      }
    });
  }

  void _handleAudioEvents() {
    _room?.addListener(() {
      for (var participant in _room!.remoteParticipants.values) {
        for (var trackPublication in participant.trackPublications.values) {
          if (trackPublication.kind == livekit.TrackType.AUDIO) {
            if (trackPublication.subscribed == true) {
              if (trackPublication.track is livekit.RemoteAudioTrack) {
                livekit.RemoteAudioTrack audioTrack =
                    trackPublication.track as livekit.RemoteAudioTrack;
                audioTrack.addListener(() {});
              }
            }
          }
        }
      }
    });
  }

  void _handleDataEvents() {
    _room?.addListener(() {
      // Handle data events if needed
    });
  }

  void dispose() {
    stopCall();
    _eventStreamController.close();
  }
}