import 'dart:convert';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:uuid/uuid.dart';

// 🔽 [신규] 현재 로그인 세션을 담을 모델
class UserSession {
  final String userId;
  final String? userName;
  final String loginProvider; // "guest", "google", "apple"
  final String? email;

  UserSession({
    required this.userId,
    this.userName,
    this.loginProvider = "guest",
    this.email,
  });

  bool get isGuest => loginProvider == "guest";
}

// 앱-고유 ID와 사용자 이름, 레벨 진행 상황을 관리하는 서비스
class IdentityService {
  // --- (모든 키 이름은 동일하게 유지) ---
  static const String _userIdKey = 'app_user_id';
  static const String _userNameKey = 'app_user_name';
  // 🔽 [신규] 로그인 상태 저장을 위한 키
  static const String _loginProviderKey = 'app_login_provider';
  static const String _userEmailKey = 'app_user_email';

  static const String _sudokuMaxLevelKey = 'max_unlocked_level';
  static const String _sudokuRankMapKey = 'last_checked_rank_map';
  static const String _spiderMaxLevelKey = 'max_unlocked_spider_level';
  static const String _spiderRankMapKey = 'last_checked_spider_rank_map';

  final _storage = const FlutterSecureStorage();

  /// 🔽 [신규] iOS 앱 간 데이터 공유를 위한 옵션
  IOSOptions _getIOSOptions() => const IOSOptions(
        // 🔽 [수정] Xcode 설정 전까지 'groupId'를 주석 처리하여 크래시 방지
        // groupId: 'group.com.lunaticbum.mygamecenter', 
      );
  
  AndroidOptions _getAndroidOptions() => const AndroidOptions(
        encryptedSharedPreferences: true,
      );

  // 🔽 [신규] 1. 현재 세션 정보를 '객체'로 가져오기
  Future<UserSession> getUserSession() async {
    final userId = await getOrCreateUserId(); // 게스트 ID는 항상 보장
    final userName = await getSavedUserName();
    final loginProvider = await _storage.read(
      key: _loginProviderKey, 
      iOptions: _getIOSOptions(), 
      aOptions: _getAndroidOptions()
    ) ?? "guest";
    final email = await _storage.read(
      key: _userEmailKey, 
      iOptions: _getIOSOptions(), 
      aOptions: _getAndroidOptions()
    );

    return UserSession(
      userId: userId,
      userName: userName,
      loginProvider: loginProvider,
      email: email,
    );
  }

  // 2. 앱-고유 ID 가져오기 (없으면 생성)
  Future<String> getOrCreateUserId() async {
    String? userId = await _storage.read(
      key: _userIdKey, 
      iOptions: _getIOSOptions(),
      aOptions: _getAndroidOptions(),
    );

    if (userId == null) {
      userId = const Uuid().v4();
      await _storage.write(
        key: _userIdKey, 
        value: userId,
        iOptions: _getIOSOptions(),
        aOptions: _getAndroidOptions(),
      );
    }
    return userId;
  }

  // 3. 랭킹에 등록한 사용자 이름 가져오기
  Future<String?> getSavedUserName() async {
    return await _storage.read(
      key: _userNameKey,
      iOptions: _getIOSOptions(),
      aOptions: _getAndroidOptions(),
    );
  }

  // 4. 랭킹 등록 성공 시, 사용자 이름 저장하기
  Future<void> saveUserName(String name) async {
    await _storage.write(
      key: _userNameKey, 
      value: name,
      iOptions: _getIOSOptions(),
      aOptions: _getAndroidOptions(),
    );
  }

  // 🔽 [신규] 5. 소셜 로그인 성공 시 호출 (계정 연결)
  Future<UserSession> saveSocialLogin({
    required String newUserId, // 서버가 발급한 마스터 계정 ID
    required String newUserName,
    required String newEmail,
    required String provider, // "google" 또는 "apple"
  }) async {
    await _storage.write(key: _userIdKey, value: newUserId, iOptions: _getIOSOptions(), aOptions: _getAndroidOptions());
    await _storage.write(key: _userNameKey, value: newUserName, iOptions: _getIOSOptions(), aOptions: _getAndroidOptions());
    await _storage.write(key: _userEmailKey, value: newEmail, iOptions: _getIOSOptions(), aOptions: _getAndroidOptions());
    await _storage.write(key: _loginProviderKey, value: provider, iOptions: _getIOSOptions(), aOptions: _getAndroidOptions());
    
    return UserSession(
      userId: newUserId,
      userName: newUserName,
      loginProvider: provider,
      email: newEmail,
    );
  }

  // 🔽 [신규] 6. 로그아웃 (게스트 계정으로 되돌리기)
  Future<UserSession> logout() async {
    // 소셜 로그인 정보만 삭제
    await _storage.delete(key: _userNameKey, iOptions: _getIOSOptions(), aOptions: _getAndroidOptions());
    await _storage.delete(key: _userEmailKey, iOptions: _getIOSOptions(), aOptions: _getAndroidOptions());
    await _storage.delete(key: _loginProviderKey, iOptions: _getIOSOptions(), aOptions: _getAndroidOptions());
    
    return await getUserSession(); 
  }

  // 7. 최대 레벨 가져오기
  Future<int> getMaxUnlockedLevel({String gameType = 'SUDOKU'}) async {
    final key = gameType == 'SPIDER' ? _spiderMaxLevelKey : _sudokuMaxLevelKey;
    String? levelString = await _storage.read(
      key: key, 
      iOptions: _getIOSOptions(),
      aOptions: _getAndroidOptions(),
    );
    return int.parse(levelString ?? '1'); // 기본값 1
  }

  // 8. 최대 레벨 저장하기
  Future<void> saveMaxUnlockedLevel(int level, {String gameType = 'SUDOKU'}) async {
    final key = gameType == 'SPIDER' ? _spiderMaxLevelKey : _sudokuMaxLevelKey;
    await _storage.write(
      key: key, 
      value: level.toString(),
      iOptions: _getIOSOptions(),
      aOptions: _getAndroidOptions(),
    );
  }

  // 9. 마지막 랭킹 맵 가져오기
  Future<Map<int, int>> getLastSavedRankMap({String gameType = 'SUDOKU'}) async {
    final key = gameType == 'SPIDER' ? _spiderRankMapKey : _sudokuRankMapKey;
    String? jsonString = await _storage.read(
      key: key, 
      iOptions: _getIOSOptions(),
      aOptions: _getAndroidOptions(),
    );

    if (jsonString == null) return {};
    try {
      final Map<String, dynamic> decodedMap = jsonDecode(jsonString);
      return decodedMap.map((key, value) => MapEntry(int.parse(key), value as int));
    } catch (e) {
      return {};
    }
  }

  // 10. 마지막 랭킹 맵 저장하기
  Future<void> saveLastRankMap(Map<int, int> rankMap, {String gameType = 'SUDOKU'}) async {
    final key = gameType == 'SPIDER' ? _spiderRankMapKey : _sudokuRankMapKey;
    
    final Map<String, int> stringKeyMap = 
        rankMap.map((key, value) => MapEntry(key.toString(), value));
        
    String jsonString = jsonEncode(stringKeyMap);
    await _storage.write(
      key: key, 
      value: jsonString,
      iOptions: _getIOSOptions(),
      aOptions: _getAndroidOptions(),
    );
  }
}