import 'package:flutter/material.dart';
import 'package:audio_service/audio_service.dart';
import 'playback_service.dart';
import 'audio_service.dart' as local_audio;

class AudioPlayerHandler extends BaseAudioHandler {
  final PlaybackService _playback = PlaybackService();
  late final local_audio.AudioService _localAudio;

  // ⭐ 切歌锁，防止重复命令
  bool _switchingTrack = false;

  AudioPlayerHandler() {
    _localAudio = local_audio.AudioService();

    // ⭐ 唯一状态来源：media_kit 的 playing 流
    _playback.player.stream.playing.listen((playing) {
      debugPrint('🎵 [stream] playing changed: $playing');
      _updatePlaybackState(playing: playing);
    });

    // ⭐ 播放完成 → 触发下一首（不直接广播状态）
    _playback.player.stream.completed.listen((_) {
      debugPrint('🎵 [stream] completed, auto next');
      _localAudio.next();  // 触发切歌，playing 流会自然变化
      // 不调用 _updatePlaybackState()
    });

    // ⭐ 歌曲变化 → 更新媒体信息（独立于播放状态）
    // 这里用 duration 变化作为“歌曲已切换”的信号
    _playback.player.stream.duration.listen((duration) {
      if (duration.inMilliseconds > 0) {
        _syncMediaItem();
      }
    });
  }

  // ============================================================
  // 状态同步链（只能由 playing 流触发）
  // ============================================================
  void _updatePlaybackState({bool? playing}) {
    final isPlaying = playing ?? _playback.player.state.playing;
    debugPrint('🎵 _updatePlaybackState: isPlaying=$isPlaying');

    final controls = [
      MediaControl.skipToPrevious,
      if (isPlaying) MediaControl.pause else MediaControl.play,
      MediaControl.skipToNext,
    ];

    debugPrint('🎵 controls: ${controls.map((c) => c.action).join(', ')}');

    playbackState.add(PlaybackState(
      controls: controls,
      processingState: AudioProcessingState.ready,
      playing: isPlaying,
      androidCompactActionIndices: const [0, 1, 2],
      updateTime: DateTime.now(),
    ));
  }

  // ============================================================
  // 媒体信息同步链（独立于播放状态）
  // ============================================================
  void _syncMediaItem() {
    final song = _localAudio.currentSong;
    if (song != null) {
      debugPrint('🎵 [sync] media item: ${song.title}');
      mediaItem.add(MediaItem(
        id: song.id,
        title: song.title,
        artist: song.artist,
        duration: _playback.player.state.duration,
      ));
    }
  }

  void updateNotification({
    required String id,
    required String title,
    required String artist,
  }) {
    mediaItem.add(MediaItem(
      id: id,
      title: title,
      artist: artist,
      duration: _playback.player.state.duration,
    ));
    _updatePlaybackState();
  }

  // ============================================================
  // 控制命令（只发命令，不宣布状态）
  // ============================================================
  @override
  Future<void> play() async {
    debugPrint('🎵 [audio_service] play() called');
    await _playback.resume();
    // ⭐ 不调用 _updatePlaybackState()
    // 等待 playing 流触发
  }

  @override
  Future<void> pause() async {
    debugPrint('🎵 [audio_service] pause() called');
    await _playback.pause();
    // ⭐ 不调用 _updatePlaybackState()
  }

  @override
  Future<void> stop() async {
    debugPrint('🎵 [audio_service] stop() called');
    await _playback.stop();
    // ⭐ 不调用 _updatePlaybackState()
  }

  @override
  Future<void> seek(Duration position) async {
    debugPrint('🎵 [audio_service] seek() called: $position');
    await _playback.seek(position);
  }

  @override
  Future<void> skipToNext() async {
    if (_switchingTrack) {
      debugPrint('🎵 skipToNext ignored: already switching');
      return;
    }
    _switchingTrack = true;
    try {
      debugPrint('🎵 [audio_service] skipToNext() called');
      await _localAudio.next();
      // ⭐ 不调用 _updatePlaybackState()
      // playing 流和 duration 流会自然触发状态更新
    } finally {
      // ⭐ 用真实状态释放锁，不用时间
      await Future.delayed(const Duration(milliseconds: 50));
      _switchingTrack = false;
    }
  }

  @override
  Future<void> skipToPrevious() async {
    if (_switchingTrack) {
      debugPrint('🎵 skipToPrevious ignored: already switching');
      return;
    }
    _switchingTrack = true;
    try {
      debugPrint('🎵 [audio_service] skipToPrevious() called');
      await _localAudio.previous();
    } finally {
      await Future.delayed(const Duration(milliseconds: 50));
      _switchingTrack = false;
    }
  }

  // ============================================================
  // click()：薄路由层，不操作播放器
  // ============================================================
  @override
  Future<void> click([MediaButton button = MediaButton.media]) async {
    debugPrint('🎵 [audio_service] click(): ${button.name} (index: ${button.index})');

    // ⭐ 用 button.name 判断，不用 index
    final name = button.name.toLowerCase();

    // 路由到标准方法
    if (name.contains('next') || name == 'next') {
      await skipToNext();
      return;
    }
    if (name.contains('previous') || name == 'previous') {
      await skipToPrevious();
      return;
    }
    if (name.contains('pause')) {
      await pause();
      return;
    }
    if (name.contains('play') || name.contains('media')) {
      await play();
      return;
    }

    // fallback: 根据当前播放状态 toggle
    debugPrint('🎵 → fallback toggle');
    if (_playback.player.state.playing) {
      await pause();
    } else {
      await play();
    }
  }
}