// LiveKit PTT protocol:
//   connect(url, token) → join LiveKit room (muted by default)
//   startSpeaking()    → enable microphone → LiveKit publishes audio track
//   stopSpeaking()     → disable microphone → LiveKit unpublishes track
//   Remote audio is played automatically by LiveKit SDK
//   ActiveSpeakersChangedEvent fires whenever a participant starts/stops speaking
import 'dart:async';

import 'package:livekit_client/livekit_client.dart';

import '../config/app_config.dart';

enum PttState { idle, connected, speaking, receiving }

class PttService {
  Room? _room;
  EventsListener<RoomEvent>? _listener;

  final _stateCtrl = StreamController<PttState>.broadcast();
  final _speakerCtrl = StreamController<String?>.broadcast();
  final _errorCtrl = StreamController<String>.broadcast();

  PttState _state = PttState.idle;
  String? _speakerName;

  Stream<PttState> get stateStream => _stateCtrl.stream;
  Stream<String?> get speakerStream => _speakerCtrl.stream;
  Stream<String> get errorStream => _errorCtrl.stream;
  PttState get currentState => _state;
  String? get currentSpeaker => _speakerName;

  void _setState(PttState s) {
    _state = s;
    _stateCtrl.add(s);
  }

  // ── Connect ──────────────────────────────────────────────────────────────
  Future<bool> connect(String url, String token) async {
    if (AppConfig.debug) {
      await Future.delayed(const Duration(milliseconds: 400));
      _setState(PttState.connected);
      return true;
    }

    try {
      _room = Room(
        roomOptions: const RoomOptions(
          adaptiveStream: false,
          dynacast: false,
        ),
      );
      _listener = _room!.createListener();

      _listener!
        ..on<ActiveSpeakersChangedEvent>(
          (e) => _onSpeakersChanged(e.speakers),
        )
        ..on<RoomDisconnectedEvent>((_) {
          _setState(PttState.idle);
        });

      await _room!.connect(url, token);

      // Start muted — mic only enabled when PTT is pressed
      await _room!.localParticipant?.setMicrophoneEnabled(false);

      _setState(PttState.connected);
      return true;
    } catch (e) {
      _errorCtrl.add('اتصال به سرور برقرار نشد');
      return false;
    }
  }

  // ── Speakers detection ────────────────────────────────────────────────────
  void _onSpeakersChanged(List<Participant> speakers) {
    // Ignore while I'm the one speaking
    if (_state == PttState.speaking) return;

    final remoteSpeakers =
        speakers.whereType<RemoteParticipant>().toList();

    if (remoteSpeakers.isNotEmpty) {
      final p = remoteSpeakers.first;
      _speakerName = p.name.isNotEmpty ? p.name : p.identity;
      _speakerCtrl.add(_speakerName);
      _setState(PttState.receiving);
    } else if (_state == PttState.receiving) {
      _speakerName = null;
      _speakerCtrl.add(null);
      _setState(PttState.connected);
    }
  }

  // ── PTT ───────────────────────────────────────────────────────────────────
  Future<void> startSpeaking() async {
    if (_state != PttState.connected) return;

    if (AppConfig.debug) {
      _setState(PttState.speaking);
      return;
    }

    try {
      await _room?.localParticipant?.setMicrophoneEnabled(true);
      _setState(PttState.speaking);
    } catch (_) {
      _errorCtrl.add('خطا در فعال‌سازی میکروفون');
    }
  }

  Future<void> stopSpeaking() async {
    if (_state != PttState.speaking) return;

    if (AppConfig.debug) {
      _setState(PttState.connected);
      _debugSimulateIncoming();
      return;
    }

    try {
      await _room?.localParticipant?.setMicrophoneEnabled(false);
      _setState(PttState.connected);
    } catch (_) {
      _setState(PttState.connected);
    }
  }

  // ── Debug helper ──────────────────────────────────────────────────────────
  Future<void> _debugSimulateIncoming() async {
    await Future.delayed(const Duration(milliseconds: 800));
    if (_state != PttState.connected) return;
    _speakerName = 'کاربر تست';
    _speakerCtrl.add(_speakerName);
    _setState(PttState.receiving);

    await Future.delayed(const Duration(seconds: 2));
    if (_state != PttState.receiving) return;
    _speakerName = null;
    _speakerCtrl.add(null);
    _setState(PttState.connected);
  }

  // ── Disconnect / Dispose ──────────────────────────────────────────────────
  Future<void> disconnect() async {
    if (AppConfig.debug) {
      _setState(PttState.idle);
      return;
    }

    try {
      await _room?.localParticipant?.setMicrophoneEnabled(false);
    } catch (_) {}

    await _listener?.dispose();
    await _room?.disconnect();
    _room = null;
    _listener = null;
    _setState(PttState.idle);
  }

  Future<void> dispose() async {
    await disconnect();
    await _stateCtrl.close();
    await _speakerCtrl.close();
    await _errorCtrl.close();
  }
}