import 'package:flutter/foundation.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:miaoji_zhang/shared/services/local_database.dart';

class OnlineFeatureRequiredException implements Exception {
  final String message;
  const OnlineFeatureRequiredException([this.message = '此功能需要登录并连接网络后使用']);

  @override
  String toString() => message;
}

class SessionStore extends ChangeNotifier {
  SessionStore._();

  static final instance = SessionStore._();

  SharedPreferences? _preferences;
  String _mode = 'none';
  int? _userId;
  String? _username;
  String? _nickname;
  String _appMode = 'normal';
  bool _onboardingDone = true;
  bool _cloudSyncEnabled = true;
  bool _needsReauth = false;
  bool _aiEnabled = false;

  bool get isGuest => _mode == 'guest';
  bool get isAccount => _mode == 'account' && _userId != null;
  bool get hasSession => isGuest || isAccount;
  bool get cloudSyncEnabled => isAccount && _cloudSyncEnabled;
  bool get needsReauth => _needsReauth;
  bool get aiEnabled => isAccount && _aiEnabled;
  bool get shouldUseLocalOnly => isGuest || !cloudSyncEnabled || needsReauth;
  int? get userId => _userId;
  String? get username => _username;
  String? get nickname => _nickname;
  String get appMode => _appMode;
  bool get onboardingDone => _onboardingDone;
  String get namespace => isGuest ? 'guest' : 'user_${_userId ?? 'none'}';

  Future<void> initialize() async {
    _preferences ??= await SharedPreferences.getInstance();
    final preferences = _preferences!;
    _mode = preferences.getString('session_mode') ?? 'none';
    _userId = preferences.getInt('session_user_id');
    _username = preferences.getString('session_username');
    _nickname = preferences.getString('session_nickname');
    _appMode = preferences.getString('session_app_mode') ?? 'normal';
    _onboardingDone = preferences.getBool('session_onboarding_done') ?? true;
    _cloudSyncEnabled = preferences.getBool('session_cloud_sync') ?? true;
    _needsReauth = preferences.getBool('session_needs_reauth') ?? false;
    _aiEnabled =
        preferences.getBool('session_ai_enabled') ?? (_mode == 'account');
    if (hasSession) {
      await LocalDatabase.instance.openNamespace(namespace);
    } else if (_mode != 'none') {
      _mode = 'none';
      await preferences.setString('session_mode', 'none');
    }
  }

  Future<void> startGuest() async {
    final preferences = _preferences ??= await SharedPreferences.getInstance();
    _mode = 'guest';
    _userId = null;
    _username = '游客';
    _nickname = '游客';
    _appMode = 'normal';
    _onboardingDone = true;
    _cloudSyncEnabled = false;
    _needsReauth = false;
    _aiEnabled = false;
    await preferences.setString('session_mode', _mode);
    await preferences.remove('session_user_id');
    await preferences.setString('session_username', _username!);
    await preferences.setString('session_nickname', _nickname!);
    await preferences.setString('session_app_mode', _appMode);
    await preferences.setBool('session_onboarding_done', true);
    await preferences.setBool('session_cloud_sync', false);
    await preferences.setBool('session_needs_reauth', false);
    await LocalDatabase.instance.openNamespace(namespace);
    notifyListeners();
  }

  Future<void> activateAccount({
    required int userId,
    required String username,
    String? nickname,
    required String appMode,
    required bool onboardingDone,
    required bool aiEnabled,
  }) async {
    final preferences = _preferences ??= await SharedPreferences.getInstance();
    _mode = 'account';
    _userId = userId;
    _username = username;
    _nickname = nickname;
    _appMode = appMode;
    _onboardingDone = onboardingDone;
    _aiEnabled = aiEnabled;
    _cloudSyncEnabled = preferences.getBool('cloud_sync_user_$userId') ?? true;
    _needsReauth = false;
    await preferences.setString('session_mode', _mode);
    await preferences.setInt('session_user_id', userId);
    await preferences.setString('session_username', username);
    if (nickname == null) {
      await preferences.remove('session_nickname');
    } else {
      await preferences.setString('session_nickname', nickname);
    }
    await preferences.setString('session_app_mode', appMode);
    await preferences.setBool('session_onboarding_done', onboardingDone);
    await preferences.setBool('session_ai_enabled', aiEnabled);
    await preferences.setBool('session_cloud_sync', _cloudSyncEnabled);
    await preferences.setBool('session_needs_reauth', false);
    await LocalDatabase.instance.openNamespace(namespace);
    notifyListeners();
  }

  Future<void> updateNickname(String? nickname) async {
    _nickname = nickname;
    notifyListeners();
    final preferences = _preferences ??= await SharedPreferences.getInstance();
    if (nickname == null) {
      await preferences.remove('session_nickname');
    } else {
      await preferences.setString('session_nickname', nickname);
    }
  }

  Future<void> updateCachedProfile({
    required String appMode,
    required bool onboardingDone,
    String? nickname,
    bool? aiEnabled,
  }) async {
    _appMode = appMode;
    _onboardingDone = onboardingDone;
    _nickname = nickname ?? _nickname;
    _aiEnabled = aiEnabled ?? _aiEnabled;
    final preferences = _preferences ??= await SharedPreferences.getInstance();
    await preferences.setString('session_app_mode', _appMode);
    await preferences.setBool('session_onboarding_done', _onboardingDone);
    await preferences.setBool('session_ai_enabled', _aiEnabled);
    if (_nickname != null) {
      await preferences.setString('session_nickname', _nickname!);
    }
    notifyListeners();
  }

  Future<void> setAiEnabled(bool enabled) async {
    if (_aiEnabled == enabled) return;
    _aiEnabled = enabled;
    if (!enabled) _appMode = 'normal';
    final preferences = _preferences ??= await SharedPreferences.getInstance();
    await preferences.setBool('session_ai_enabled', enabled);
    if (!enabled) await preferences.setString('session_app_mode', 'normal');
    notifyListeners();
  }

  Future<void> setCloudSyncEnabled(bool enabled) async {
    if (!isAccount) return;
    _cloudSyncEnabled = enabled;
    final preferences = _preferences ??= await SharedPreferences.getInstance();
    await preferences.setBool('session_cloud_sync', enabled);
    await preferences.setBool('cloud_sync_user_$_userId', enabled);
    notifyListeners();
  }

  Future<void> markNeedsReauth() async {
    if (!isAccount || _needsReauth) return;
    _needsReauth = true;
    final preferences = _preferences ??= await SharedPreferences.getInstance();
    await preferences.setBool('session_needs_reauth', true);
    notifyListeners();
  }

  Future<void> clearActiveSession() async {
    final preferences = _preferences ??= await SharedPreferences.getInstance();
    _mode = 'none';
    _userId = null;
    _username = null;
    _nickname = null;
    _appMode = 'normal';
    _onboardingDone = true;
    _cloudSyncEnabled = true;
    _needsReauth = false;
    _aiEnabled = false;
    await preferences.setString('session_mode', 'none');
    await preferences.remove('session_user_id');
    await preferences.remove('session_username');
    await preferences.remove('session_nickname');
    await preferences.remove('session_needs_reauth');
    LocalDatabase.instance.close();
    notifyListeners();
  }

  void requireOnline([String? message]) {
    if (shouldUseLocalOnly) {
      throw OnlineFeatureRequiredException(message ?? '此功能需要登录并连接网络后使用');
    }
  }
}