import 'package:shared_preferences/shared_preferences.dart';
import 'package:travel_mate/models/album_photo.dart';

/// Stores shared album photos per trip locally for offline access.
class AlbumService {
  /// Loads photos for the given trip.
  Future<List<AlbumPhoto>> loadPhotos(String tripId) async {
    final prefs = await SharedPreferences.getInstance();
    final raw = prefs.getString(_key(tripId));
    if (raw == null) return const [];
    try {
      return AlbumPhoto.decodeList(raw);
    } catch (_) {
      await prefs.remove(_key(tripId));
      return const [];
    }
  }

  /// Saves photo list.
  Future<void> savePhotos(String tripId, List<AlbumPhoto> photos) async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(_key(tripId), AlbumPhoto.encodeList(photos));
  }

  /// Adds one photo.
  Future<List<AlbumPhoto>> addPhoto(String tripId, AlbumPhoto photo) async {
    final current = await loadPhotos(tripId);
    final updated = [...current, photo];
    await savePhotos(tripId, updated);
    return updated;
  }

  /// Deletes a photo.
  Future<List<AlbumPhoto>> deletePhoto(String tripId, String photoId) async {
    final current = await loadPhotos(tripId);
    final updated = current.where((p) => p.id != photoId).toList();
    await savePhotos(tripId, updated);
    return updated;
  }

  String _key(String tripId) => 'album_$tripId';
}