Melo/lib/library/playlist_service.dart

import 'package:flutter/foundation.dart';
import 'database.dart';

/// Koordiniert Playlisten- und Favoriten-Operationen; benachrichtigt Listener
/// nach jeder Mutation (für Feedback wie SnackBars — die Listen selbst
/// beobachten UIs direkt über die watch()-Streams von [MeloDb]).
class PlaylistService extends ChangeNotifier {
  PlaylistService(this.db);
  final MeloDb db;

  Future<String> createPlaylist(String name, {String? description}) async {
    final id = await db.createPlaylist(name, description: description);
    notifyListeners();
    return id;
  }

  Future<void> deletePlaylist(String id) async {
    await db.deletePlaylist(id);
    notifyListeners();
  }

  Future<void> addSongToPlaylist(String playlistId, String songId, int position) async {
    await db.addSongToPlaylist(playlistId, songId, position);
    notifyListeners();
  }

  Future<void> removeSongFromPlaylist(String playlistId, String songId) async {
    await db.removeSongFromPlaylist(playlistId, songId);
    notifyListeners();
  }

  Future<void> reorderSong(String playlistId, String songId, int newPosition) async {
    await db.reorderPlaylistSong(playlistId, songId, newPosition);
    notifyListeners();
  }

  Future<void> reorderAll(String playlistId, List<String> orderedSongIds) async {
    await db.reorderAllPlaylistSongs(playlistId, orderedSongIds);
    notifyListeners();
  }

  Future<void> toggleFavorite(String songId) async {
    await db.toggleFavorite(songId);
    notifyListeners();
  }
}