import 'dart:async';
import 'dart:io';
import 'dart:math';

import 'package:flutter/foundation.dart';
import 'package:yumi/services/audio/rtc_manager.dart';
import 'package:yumi/services/audio/room_rtc_types.dart';
import 'package:yumi/services/music/room_music_repository.dart';
import 'package:yumi/shared/data_sources/models/sc_music_folder_mode.dart';
import 'package:yumi/shared/data_sources/models/sc_music_mode.dart';
import 'package:yumi/ui_kit/components/sc_tts.dart';

enum RoomMusicPlayMode { list, shuffle, single }

class RoomMusicManager extends ChangeNotifier {
  static const Duration _publishingStateHeartbeatInterval = Duration(
    seconds: 5,
  );

  RoomMusicManager({RoomMusicRepository? repository})
    : _repository = repository ?? RoomMusicRepository() {
    _playlist = _repository.loadSongs();
  }

  final RoomMusicRepository _repository;
  final Random _random = Random();

  RtcProvider? _rtcProvider;
  Timer? _positionTimer;
  Timer? _publishingStateHeartbeatTimer;
  List<SCMusicMode> _playlist = <SCMusicMode>[];
  SCMusicMode? _current;
  RoomMusicPlayMode _playMode = RoomMusicPlayMode.list;
  int _volume = 70;
  int _positionMs = 0;
  int _durationMs = 0;
  int _lastStartAtMs = 0;
  int _ignoreStoppedUntilMs = 0;
  bool _isPlaying = false;
  bool _isPaused = false;
  bool _isStarting = false;
  bool _isStoppingByUser = false;
  bool _isRoutingSwitching = false;
  bool _lastPublishedRoomState = false;
  bool _lastLoopback = true;
  bool _roomPlayerVisible = false;

  List<SCMusicMode> get playlist => List.unmodifiable(_playlist);

  SCMusicMode? get current => _current;

  RoomMusicPlayMode get playMode => _playMode;

  int get volume => _volume;

  int get positionMs => _positionMs;

  int get durationMs =>
      _durationMs > 0 ? _durationMs : (_current?.durationMs ?? 0);

  bool get isPlaying => _isPlaying;

  bool get isPaused => _isPaused;

  bool get hasCurrent => _current != null;

  bool get roomPlayerVisible => _roomPlayerVisible;

  bool get isPublishingToRoom =>
      _isPlaying &&
      !_isPaused &&
      !_lastLoopback &&
      (_rtcProvider?.isOnMai() ?? false);

  int get currentIndex {
    final currentId = _current?.id;
    if (currentId == null) {
      return -1;
    }
    return _playlist.indexWhere((item) => item.id == currentId);
  }

  void attachRtcProvider(RtcProvider provider) {
    if (_rtcProvider == provider) {
      return;
    }
    _rtcProvider?.setRoomMusicMixingStateListener(null);
    _rtcProvider?.setRoomMusicMicRouteChangedListener(null);
    _rtcProvider = provider;
    provider.setRoomMusicMixingStateListener(_handleMixingStateChanged);
    provider.setRoomMusicMicRouteChangedListener(_handleMicRouteChanged);
    _syncPublishingState(force: true);
  }

  Future<void> reload() async {
    _playlist = _repository.loadSongs();
    _restoreCurrentAfterPlaylistChange();
    notifyListeners();
  }

  Future<void> applyFolderSelection({
    required SCMusicFolderMode folder,
    required Set<String> selectedIds,
  }) async {
    final currentById = {for (final item in _playlist) item.id: item};
    final folderIds = folder.songs.map((item) => item.id).toSet();
    final next = <SCMusicMode>[
      ..._playlist.where((item) => !folderIds.contains(item.id)),
    ];
    final now = DateTime.now().millisecondsSinceEpoch;
    for (final song in folder.songs) {
      if (!selectedIds.contains(song.id)) {
        continue;
      }
      final existing = currentById[song.id];
      next.add(
        (existing ?? song).copyWith(
          addedAt:
              existing?.addedAt == null || existing!.addedAt <= 0
                  ? now
                  : existing.addedAt,
        ),
      );
    }
    await _savePlaylist(next);
  }

  Future<void> deleteMusic(SCMusicMode item) async {
    final deletingCurrent = _current?.id == item.id;
    if (deletingCurrent) {
      await stop(clearCurrent: true);
    }
    await _savePlaylist(_playlist.where((song) => song.id != item.id).toList());
  }

  Future<void> reorder(int oldIndex, int newIndex) async {
    if (oldIndex < 0 || oldIndex >= _playlist.length) {
      return;
    }
    final next = [..._playlist];
    if (newIndex > oldIndex) {
      newIndex -= 1;
    }
    final item = next.removeAt(oldIndex);
    next.insert(newIndex.clamp(0, next.length).toInt(), item);
    await _savePlaylist(next);
  }

  Future<void> play(
    SCMusicMode item, {
    int startPositionMs = 0,
    bool showRoomPlayer = true,
  }) async {
    if (item.playPath.isEmpty) {
      SCTts.show("Music file not found");
      return;
    }
    if (!item.playPath.startsWith("content://") &&
        !File(item.localPath).existsSync()) {
      SCTts.show("Music file not found");
      await deleteMusic(item);
      return;
    }
    _current = item;
    _durationMs = item.durationMs;
    _positionMs = startPositionMs;
    _isPaused = false;
    if (showRoomPlayer) {
      _roomPlayerVisible = true;
    }
    await _startCurrent(startPositionMs: startPositionMs);
  }

  Future<void> pause() async {
    if (!_isPlaying || _rtcProvider == null) {
      return;
    }
    await _rtcProvider?.pauseRoomMusicAudioMixing();
    _isPlaying = false;
    _isPaused = true;
    _stopPositionTimer();
    _syncPublishingState();
    notifyListeners();
  }

  Future<void> resume() async {
    if (_current == null || _rtcProvider == null) {
      return;
    }
    if (_isPaused) {
      final nextLoopback = !_rtcProvider!.isOnMai();
      if (nextLoopback != _lastLoopback) {
        final wasRoomPlayerVisible = _roomPlayerVisible;
        _ignoreStoppedUntilMs = DateTime.now().millisecondsSinceEpoch + 900;
        _isRoutingSwitching = true;
        try {
          await _rtcProvider?.stopRoomMusicAudioMixing();
          await _startCurrent(startPositionMs: _positionMs);
          _roomPlayerVisible = wasRoomPlayerVisible;
        } finally {
          _isRoutingSwitching = false;
        }
        return;
      }
      await _rtcProvider?.resumeRoomMusicAudioMixing();
      _isPlaying = true;
      _isPaused = false;
      _startPositionTimer();
      _syncPublishingState();
      notifyListeners();
      return;
    }
    await _startCurrent(startPositionMs: _positionMs);
  }

  Future<void> stop({bool clearCurrent = false}) async {
    _isStoppingByUser = true;
    try {
      await _rtcProvider?.stopRoomMusicAudioMixing();
    } catch (_) {
      // Ignore stop failures; local state must still be reset.
    } finally {
      _isStoppingByUser = false;
      _stopPositionTimer();
      _isPlaying = false;
      _isPaused = false;
      _positionMs = 0;
      if (clearCurrent) {
        _current = null;
        _durationMs = 0;
        _roomPlayerVisible = false;
      }
      _syncPublishingState(force: clearCurrent);
      notifyListeners();
    }
  }

  Future<void> stopForRoomExit() async {
    await stop(clearCurrent: true);
  }

  Future<void> previous() async {
    if (_playlist.isEmpty) {
      return;
    }
    final index = currentIndex;
    final targetIndex = index <= 0 ? _playlist.length - 1 : index - 1;
    await play(_playlist[targetIndex]);
  }

  Future<void> next({bool fromAutoComplete = false}) async {
    if (_playlist.isEmpty) {
      await stop(clearCurrent: true);
      return;
    }
    if (_playMode == RoomMusicPlayMode.single && fromAutoComplete) {
      await play(_current ?? _playlist.first, showRoomPlayer: false);
      return;
    }
    int targetIndex = 0;
    final index = currentIndex;
    if (_playMode == RoomMusicPlayMode.shuffle) {
      if (_playlist.length == 1) {
        targetIndex = 0;
      } else {
        do {
          targetIndex = _random.nextInt(_playlist.length);
        } while (targetIndex == index);
      }
    } else {
      targetIndex = index < 0 ? 0 : (index + 1) % _playlist.length;
    }
    await play(_playlist[targetIndex], showRoomPlayer: !fromAutoComplete);
  }

  Future<void> seek(int positionMs) async {
    final safePosition = positionMs.clamp(0, durationMs).toInt();
    _positionMs = safePosition;
    await _rtcProvider?.setRoomMusicAudioMixingPosition(safePosition);
    notifyListeners();
  }

  Future<void> setVolume(int volume) async {
    _volume = volume.clamp(0, 100).toInt();
    await _rtcProvider?.setRoomMusicAudioMixingVolume(_volume);
    notifyListeners();
  }

  String switchPlayMode() {
    switch (_playMode) {
      case RoomMusicPlayMode.list:
        _playMode = RoomMusicPlayMode.shuffle;
        notifyListeners();
        return "随机播放";
      case RoomMusicPlayMode.shuffle:
        _playMode = RoomMusicPlayMode.single;
        notifyListeners();
        return "单曲循环播放";
      case RoomMusicPlayMode.single:
        _playMode = RoomMusicPlayMode.list;
        notifyListeners();
        return "列表顺序播放";
    }
  }

  void toggleRoomPlayerVisible() {
    if (_current == null) {
      return;
    }
    _roomPlayerVisible = !_roomPlayerVisible;
    notifyListeners();
  }

  void hideRoomPlayer() {
    if (!_roomPlayerVisible) {
      return;
    }
    _roomPlayerVisible = false;
    notifyListeners();
  }

  Future<void> syncPlaybackRouting() async {
    final current = _current;
    final rtcProvider = _rtcProvider;
    if (current == null || rtcProvider == null || !_isPlaying) {
      return;
    }
    final nextLoopback = !rtcProvider.isOnMai();
    if (nextLoopback == _lastLoopback) {
      return;
    }
    final position = await rtcProvider
        .getRoomMusicAudioMixingPosition()
        .catchError((_) => _positionMs);
    _ignoreStoppedUntilMs = DateTime.now().millisecondsSinceEpoch + 900;
    final wasRoomPlayerVisible = _roomPlayerVisible;
    _isRoutingSwitching = true;
    try {
      await rtcProvider.stopRoomMusicAudioMixing();
      await _startCurrent(startPositionMs: position);
      _roomPlayerVisible = wasRoomPlayerVisible;
    } catch (_) {
      _isPlaying = false;
      _isPaused = false;
      _syncPublishingState();
      notifyListeners();
    } finally {
      _isRoutingSwitching = false;
    }
  }

  Future<void> _savePlaylist(List<SCMusicMode> songs) async {
    await _repository.saveSongs(songs);
    _playlist = _repository.loadSongs();
    _restoreCurrentAfterPlaylistChange();
    notifyListeners();
  }

  Future<void> _startCurrent({required int startPositionMs}) async {
    final current = _current;
    final rtcProvider = _rtcProvider;
    if (current == null || rtcProvider == null || _isStarting) {
      return;
    }
    _isStarting = true;
    try {
      await _waitForStartInterval();
      _lastLoopback = !rtcProvider.isOnMai();
      await rtcProvider.startRoomMusicAudioMixing(
        filePath: current.playPath,
        loopback: _lastLoopback,
        cycle: 1,
        startPos: startPositionMs,
      );
      _lastStartAtMs = DateTime.now().millisecondsSinceEpoch;
      await rtcProvider.setRoomMusicAudioMixingVolume(_volume);
      _positionMs = startPositionMs;
      _durationMs =
          current.durationMs > 0
              ? current.durationMs
              : await rtcProvider.getRoomMusicAudioMixingDuration();
      _isPlaying = true;
      _isPaused = false;
      _startPositionTimer();
      _syncPublishingState();
      notifyListeners();
    } catch (_) {
      _isPlaying = false;
      _isPaused = false;
      _stopPositionTimer();
      _syncPublishingState();
      SCTts.show("Music playback failed");
      notifyListeners();
    } finally {
      _isStarting = false;
    }
  }

  Future<void> _waitForStartInterval() async {
    final now = DateTime.now().millisecondsSinceEpoch;
    final elapsed = now - _lastStartAtMs;
    if (elapsed < 550) {
      await Future<void>.delayed(Duration(milliseconds: 550 - elapsed));
    }
  }

  void _startPositionTimer() {
    _positionTimer?.cancel();
    _positionTimer = Timer.periodic(const Duration(milliseconds: 800), (_) {
      unawaited(_refreshPosition());
    });
  }

  void _stopPositionTimer() {
    _positionTimer?.cancel();
    _positionTimer = null;
  }

  Future<void> _refreshPosition() async {
    if (!_isPlaying || _rtcProvider == null) {
      return;
    }
    try {
      final position = await _rtcProvider!.getRoomMusicAudioMixingPosition();
      final duration = await _rtcProvider!.getRoomMusicAudioMixingDuration();
      if (position >= 0) {
        _positionMs = position;
      }
      if (duration > 0) {
        _durationMs = duration;
      }
      notifyListeners();
    } catch (_) {
      // Position polling is best-effort only.
    }
  }

  void _handleMixingStateChanged(
    RoomRtcAudioMixingState state,
    RoomRtcAudioMixingReason reason,
  ) {
    switch (state) {
      case RoomRtcAudioMixingState.playing:
        _isPlaying = true;
        _isPaused = false;
        _startPositionTimer();
        _syncPublishingState();
        notifyListeners();
        break;
      case RoomRtcAudioMixingState.paused:
        _isPlaying = false;
        _isPaused = true;
        _stopPositionTimer();
        _syncPublishingState();
        notifyListeners();
        break;
      case RoomRtcAudioMixingState.stopped:
        if (_isRoutingSwitching) {
          return;
        }
        if (DateTime.now().millisecondsSinceEpoch < _ignoreStoppedUntilMs) {
          return;
        }
        _stopPositionTimer();
        if (reason == RoomRtcAudioMixingReason.allLoopsCompleted) {
          unawaited(next(fromAutoComplete: true));
          return;
        }
        if (!_isStoppingByUser) {
          _isPlaying = false;
          _isPaused = false;
          _positionMs = 0;
          _syncPublishingState();
          notifyListeners();
        }
        break;
      case RoomRtcAudioMixingState.failed:
        _stopPositionTimer();
        _isPlaying = false;
        _isPaused = false;
        _syncPublishingState();
        SCTts.show("Music playback failed");
        notifyListeners();
        break;
    }
  }

  void _handleMicRouteChanged(bool isOnMic) {
    unawaited(syncPlaybackRouting());
    _syncPublishingState();
  }

  void _syncPublishingState({bool force = false}) {
    final rtcProvider = _rtcProvider;
    if (rtcProvider == null) {
      _updatePublishingStateHeartbeat(false);
      return;
    }
    final publishing = isPublishingToRoom;
    _updatePublishingStateHeartbeat(publishing);
    if (!force && publishing == _lastPublishedRoomState) {
      return;
    }
    _lastPublishedRoomState = publishing;
    rtcProvider.publishCurrentUserRoomMusicState(publishing);
  }

  void _updatePublishingStateHeartbeat(bool publishing) {
    if (!publishing) {
      _publishingStateHeartbeatTimer?.cancel();
      _publishingStateHeartbeatTimer = null;
      return;
    }
    if (_publishingStateHeartbeatTimer != null) {
      return;
    }
    _publishingStateHeartbeatTimer = Timer.periodic(
      _publishingStateHeartbeatInterval,
      (_) {
        if (!isPublishingToRoom) {
          _publishingStateHeartbeatTimer?.cancel();
          _publishingStateHeartbeatTimer = null;
          _syncPublishingState(force: true);
          return;
        }
        _rtcProvider?.publishCurrentUserRoomMusicState(true);
      },
    );
  }

  void _restoreCurrentAfterPlaylistChange() {
    final currentId = _current?.id;
    if (currentId == null) {
      return;
    }
    final index = _playlist.indexWhere((item) => item.id == currentId);
    if (index >= 0) {
      _current = _playlist[index];
      return;
    }
    _current = null;
    _isPlaying = false;
    _isPaused = false;
    _syncPublishingState(force: true);
    _roomPlayerVisible = false;
    _positionMs = 0;
    _durationMs = 0;
    _stopPositionTimer();
  }

  @override
  void dispose() {
    _positionTimer?.cancel();
    _publishingStateHeartbeatTimer?.cancel();
    _rtcProvider?.setRoomMusicMixingStateListener(null);
    _rtcProvider?.setRoomMusicMicRouteChangedListener(null);
    super.dispose();
  }
}