import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:just_audio/just_audio.dart';
import '../models/song.dart';

class PlayerService {
  static final PlayerService _instanz = PlayerService._();
  factory PlayerService() => _instanz;
  PlayerService._();

  AudioPlayer? _player;
  final List<Song> _warteschlange = [];
  int _aktuellerIndex = -1;
  StreamSubscription<PlayerState>? _autoNextSub;

  AudioPlayer get _p {
    if (_player == null) {
      _player = AudioPlayer();
      _autoNextSub = _player!.playerStateStream.listen((state) {
        if (state.processingState == ProcessingState.completed) {
          naechstes();
        }
      });
    }
    return _player!;
  }

  Song? get aktuellerSong => _aktuellerIndex >= 0 && _aktuellerIndex < _warteschlange.length
    ? _warteschlange[_aktuellerIndex] : null;
  bool get spieltAb => _player?.playing ?? false;
  Duration get position => _player?.position ?? Duration.zero;
  Duration get dauer => _player?.duration ?? Duration.zero;
  Stream<Duration> get positionStream => _p.positionStream;
  Stream<PlayerState> get stateStream => _p.playerStateStream;

  final StreamController<Song?> _songWechsel = StreamController.broadcast();
  Stream<Song?> get onSongWechsel => _songWechsel.stream;

  Future<void> spiele(Song song, {int position = 0}) async {
    _aktuellerIndex = _warteschlange.indexWhere((s) => s.id == song.id);
    if (_aktuellerIndex < 0) {
      _warteschlange.add(song);
      _aktuellerIndex = _warteschlange.length - 1;
    }
    try {
      await _p.setFilePath(song.dateiPfad);
      if (position > 0) await _p.seek(Duration(seconds: position));
      await _p.play();
      _songWechsel.add(song);
    } catch (e) {
      debugPrint('Fehler beim Abspielen: $e');
    }
  }

  Future<void> playPause() async {
    if (_player == null) return;
    if (_p.playing) {
      await _p.pause();
    } else if (aktuellerSong != null) {
      await _p.play();
    }
  }

  Future<void> vorheriges() async {
    if (_player == null || aktuellerSong == null) return;
    final pos = _p.position;
    if (pos.inSeconds > 5) {
      await _p.seek(Duration.zero);
    } else {
      final neuerIndex = _aktuellerIndex - 1;
      if (neuerIndex >= 0) {
        await spiele(_warteschlange[neuerIndex]);
      }
    }
  }

  Future<void> naechstes() async {
    final neuerIndex = _aktuellerIndex + 1;
    if (neuerIndex < _warteschlange.length) {
      await spiele(_warteschlange[neuerIndex]);
    }
  }

  void setWarteschlange(List<Song> songs, {int startIndex = 0}) {
    _warteschlange.clear();
    _warteschlange.addAll(songs);
    _aktuellerIndex = startIndex;
  }

  void dispose() {
    _autoNextSub?.cancel();
    _player?.dispose();
    _songWechsel.close();
  }
}