import 'dart:convert';
import 'package:shared_preferences/shared_preferences.dart';
import '../models/event.dart';

class ScheduleCacheService {
  String _eventsKey(String account) => 'cached_events_$account';
  String _agegroupKey(String account) => 'filters_agegroup_$account';
  String _subgroupKey(String account) => 'filters_subgroup_$account';
  String _timestampKey(String account) => 'cached_events_timestamp_$account';

  Future<void> saveEvents(String account, List<Event> events) async {
    final prefs = await SharedPreferences.getInstance();
    final jsonList = events.map((e) => e.toJson()).toList();
    await prefs.setString(_eventsKey(account), jsonEncode(jsonList));
    await prefs.setInt(
      _timestampKey(account),
      DateTime.now().millisecondsSinceEpoch,
    );
  }

  Future<List<Event>?> loadEvents(String account) async {
    final prefs = await SharedPreferences.getInstance();
    final jsonString = prefs.getString(_eventsKey(account));
    if (jsonString == null) return null;
    try {
      final jsonList = jsonDecode(jsonString) as List<dynamic>;
      return jsonList
          .map((json) => Event.fromJson(json as Map<String, dynamic>))
          .toList();
    } catch (e) {
      return null;
    }
  }

  Future<DateTime?> getLastUpdated(String account) async {
    final prefs = await SharedPreferences.getInstance();
    final timestamp = prefs.getInt(_timestampKey(account));
    if (timestamp == null) return null;
    return DateTime.fromMillisecondsSinceEpoch(timestamp);
  }

  Future<void> saveFilters(
    String account,
    String? agegroup,
    String? subgroup,
  ) async {
    final prefs = await SharedPreferences.getInstance();
    if (agegroup != null) {
      await prefs.setString(_agegroupKey(account), agegroup);
    } else {
      await prefs.remove(_agegroupKey(account));
    }
    if (subgroup != null) {
      await prefs.setString(_subgroupKey(account), subgroup);
    } else {
      await prefs.remove(_subgroupKey(account));
    }
  }

  Future<(String?, String?)> loadFilters(String account) async {
    final prefs = await SharedPreferences.getInstance();
    return (
      prefs.getString(_agegroupKey(account)),
      prefs.getString(_subgroupKey(account)),
    );
  }

  Future<void> clearCache(String account) async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(_eventsKey(account));
    await prefs.remove(_timestampKey(account));
    await prefs.remove(_agegroupKey(account));
    await prefs.remove(_subgroupKey(account));
  }

  Future<void> clearAllCache() async {
    final prefs = await SharedPreferences.getInstance();
    final keys = prefs.getKeys().where((k) => k.startsWith('cached_events_') ||
        k.startsWith('filters_') ||
        k.startsWith('cached_events_timestamp_'));
    for (final key in keys) {
      await prefs.remove(key);
    }
  }
}