import 'dart:convert';

/// 离线缓存服务
/// 基于 Hive 提供本地数据存储能力
class CacheService {
  static CacheService? _instance;
  final Map<String, dynamic> _memoryCache = {};
  bool _isInitialized = false;

  CacheService._internal();

  factory CacheService() {
    _instance ??= CacheService._internal();
    return _instance!;
  }

  /// 初始化缓存（打开 Hive Box）
  Future<void> initialize() async {
    if (_isInitialized) return;

    try {
      // TODO: 初始化 Hive
      // await Hive.initFlutter();
      // await Hive.openBox(AppConstants.cacheBoxName);
      // await Hive.openBox(AppConstants.userBoxName);
      _isInitialized = true;
      print('[CacheService] 缓存服务已初始化（模拟）');
    } catch (e) {
      print('[CacheService] 初始化失败: $e');
    }
  }

  /// 写入缓存
  Future<void> put(String key, dynamic value, {String box = 'default'}) async {
    try {
      // TODO: 使用 Hive 持久化
      // final cacheBox = Hive.box(AppConstants.cacheBoxName);
      // await cacheBox.put(key, value);
      _memoryCache['$box:$key'] = value;
    } catch (e) {
      print('[CacheService] 写入缓存失败: $e');
    }
  }

  /// 读取缓存
  Future<T?> get<T>(String key, {String box = 'default'}) async {
    try {
      // TODO: 使用 Hive 读取
      // final cacheBox = Hive.box(AppConstants.cacheBoxName);
      // return cacheBox.get(key) as T?;
      return _memoryCache['$box:$key'] as T?;
    } catch (e) {
      print('[CacheService] 读取缓存失败: $e');
      return null;
    }
  }

  /// 删除缓存
  Future<void> delete(String key, {String box = 'default'}) async {
    try {
      _memoryCache.remove('$box:$key');
    } catch (e) {
      print('[CacheService] 删除缓存失败: $e');
    }
  }

  /// 清空指定 Box 的所有缓存
  Future<void> clearBox({String box = 'default'}) async {
    try {
      _memoryCache.removeWhere((key, _) => key.startsWith('$box:'));
    } catch (e) {
      print('[CacheService] 清空缓存失败: $e');
    }
  }

  /// 清空所有缓存
  Future<void> clearAll() async {
    try {
      _memoryCache.clear();
    } catch (e) {
      print('[CacheService] 清空所有缓存失败: $e');
    }
  }

  /// 缓存 JSON 对象
  Future<void> cacheJson(String key, Map<String, dynamic> data, {String box = 'default'}) async {
    await put(key, json.encode(data), box: box);
  }

  /// 读取缓存的 JSON 对象
  Future<Map<String, dynamic>?> getCachedJson(String key, {String box = 'default'}) async {
    final data = await get<String>(key, box: box);
    if (data == null) return null;
    try {
      return json.decode(data) as Map<String, dynamic>;
    } catch (e) {
      return null;
    }
  }

  /// 缓存列表数据
  Future<void> cacheList(String key, List<Map<String, dynamic>> items, {String box = 'default'}) async {
    await put(key, json.encode(items), box: box);
  }

  /// 读取缓存的列表数据
  Future<List<Map<String, dynamic>>?> getCachedList(String key, {String box = 'default'}) async {
    final data = await get<String>(key, box: box);
    if (data == null) return null;
    try {
      final decoded = json.decode(data) as List;
      return decoded.cast<Map<String, dynamic>>();
    } catch (e) {
      return null;
    }
  }

  /// 检查是否有缓存
  Future<bool> has(String key, {String box = 'default'}) async {
    return _memoryCache.containsKey('$box:$key');
  }
}