melo-app/lib/services/favoriten_service.dart

import '../database/db_helper.dart';
import '../models/song.dart';

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

  final DbHelper _db = DbHelper();
  int? _favoritenPlaylistId;

  int? get favoritenId => _favoritenPlaylistId;

  Future<void> init() async {
    final playlists = await _db.allePlaylists();
    final vorhanden = playlists.where((p) => p['name'] == '⭐ Favoriten').toList();
    if (vorhanden.isNotEmpty) {
      _favoritenPlaylistId = vorhanden.first['id'] as int;
    } else {
      _favoritenPlaylistId = await _db.playlistErstellen('⭐ Favoriten');
    }
  }

  Future<bool> istFavorit(int songId) async {
    if (_favoritenPlaylistId == null) return false;
    final songs = await _db.songsDerPlaylist(_favoritenPlaylistId!);
    return songs.any((s) => s.id == songId);
  }

  Future<void> umschalten(int songId) async {
    if (_favoritenPlaylistId == null) return;
    if (await istFavorit(songId)) {
      await _db.songAusPlaylistEntfernen(_favoritenPlaylistId!, songId);
    } else {
      final songs = await _db.songsDerPlaylist(_favoritenPlaylistId!);
      await _db.songZurPlaylist(_favoritenPlaylistId!, songId, songs.length);
    }
  }

  Future<List<Song>> alleFavoriten() async {
    if (_favoritenPlaylistId == null) return [];
    return _db.songsDerPlaylist(_favoritenPlaylistId!);
  }

  Future<int> anzahlFavoriten() async {
    if (_favoritenPlaylistId == null) await init();
    if (_favoritenPlaylistId == null) return 0;
    final songs = await _db.songsDerPlaylist(_favoritenPlaylistId!);
    return songs.length;
  }

  Future<Set<int>> favoritenIds() async {
    if (_favoritenPlaylistId == null) return {};
    final d = await _db.db;
    final rows = await d.rawQuery(
      'SELECT song_id FROM playlist_songs WHERE playlist_id = ?',
      [_favoritenPlaylistId],
    );
    return rows.map((r) => r['song_id'] as int).toSet();
  }
}