import 'dart:convert';
import 'dart:developer';
import 'dart:math' as math;

import 'package:injectable/injectable.dart';
import 'package:drift/drift.dart' as drift;
import 'package:mnemo_cards_backend/database/database.dart';
import 'package:mnemo_cards_common_backend/mnemo_cards_common_backend.dart';
import 'package:mnemo_cards_common/mnemo_cards_common.dart';

import '../packs/free_packs_distributor.dart';
import '../statistics/session_tracker.dart';
import '../statistics/statistics_calculator.dart';
import '../statistics/achievement_manager.dart';
import 'secure.dart';
import 'user_drift_extension.dart';

Map<String?, DateTime> _onlineUsers = {};

@lazySingleton
class UserManager {
  final AppDatabase _db;
  final FreePacksDistributor _freePacksDistributor;
  final SessionTracker _sessionTracker;
  final StatisticsCalculator _statisticsCalculator;
  final AchievementManager _achievementManager;

  UserManager(
    this._db,
    this._freePacksDistributor,
    this._sessionTracker,
    this._statisticsCalculator,
    this._achievementManager,
  );

  Future<UserModel?> fetchUser(String id) async {
    final user = await _db.userDao.getUserById(id);
    if (user == null) return null;
    return await user.toUserModel();
  }

  DateTime? lastOnline(String id) => _onlineUsers[id];

  Future<String> createOrGetAuthToken(UserModel user, String externalId) async {
    if (user.id == null) {
      throw Exception('Cant create token for empty id');
    }
    final now = DateTime.now();
    final token = await _db.userDao.getTokenByUserId(user.id!);
    if (token != null) {
      if (token.expires.isAfter(now)) {
        return token.token;
      }
      await _db.userDao.deleteToken(token.id);
    }
    final userToken = Secure.token();
    await _db.userDao.createToken(
      TokensCompanion.insert(
        token: userToken,
        externalUserId: externalId,
        userId: user.id!,
        expires: now.add(const Duration(days: 360)),
      ),
    );
    return userToken;
  }

  Future<UserModel?> getUserByToken(String authToken) async {
    final token = await _db.userDao.getTokenByValue(authToken);
    if (token == null) {
      return null;
    }
    final now = DateTime.now();
    if (token.expires.isBefore(now)) {
      await _db.userDao.deleteToken(token.id);
      return null;
    }
    final user = await fetchUser(token.userId);
    if (user != null) {
      _onlineUsers[token.userId] = now;
      if (_onlineUsers.length > 300) {
        updateOnlineUsers();
      }
    }
    return user;
  }

  Future<void> updateOnlineUsers() async {
    if (_onlineUsers.isEmpty) {
      return;
    }

    final userIds = _onlineUsers.keys.whereNotNull().toList();

    for (final userId in userIds) {
      final lastOnline = _onlineUsers[userId];
      if (lastOnline != null) {
        await _db.userDao.updateUserDataPartial(
          UserDatasCompanion(
            userId: drift.Value(userId),
            lastTimeOnline: drift.Value(lastOnline),
            updatedAt: drift.Value(DateTime.now()),
          ),
        );
      }
    }

    _onlineUsers.clear();
  }

  Future<(UserModel, String)> createOrGetUser({
    required String externalId,
    required String email,
    String? name,
  }) async {
    // Check if user exists by externalId
    final existingUser = await _db.userDao.getUserByExternalId(externalId);
    if (existingUser != null) {
      print('User found $name $email');
      final userModel = await existingUser.toUserModel();
      final token = await createOrGetAuthToken(userModel, externalId);
      return (userModel, token);
    }

    print('Creating new user $name $email');

    // Create new user
    final userCompanion = UsersCompanion.insert(
      externalUserId: externalId,
      name: drift.Value(name),
      email: drift.Value(email),
    );

    final userId = await _db.userDao.createUser(userCompanion);

    // Create user data
    await _db.userDao.createUserData(
      UserDatasCompanion.insert(
        userId: userId,
        registrationDate: drift.Value(DateTime.now()),
      ),
    );

    final user = await _db.userDao.getUserById(userId);
    if (user == null) {
      throw Exception('Failed to create user');
    }

    final userModel = await user.toUserModel();
    final token = await createOrGetAuthToken(userModel, externalId);

    // Give free packs to new user
    await _freePacksDistributor.giveFreePacksToUser(userModel);

    print('User $name $email created successfully');
    return (userModel, token);
  }

  /// Обновить настройки пользователя
  Future<void> updateUserSettings(UserModel user, UserSettingsDto settings) async {
    if (user.id == null) {
      throw Exception('User ID is required');
    }

    await _db.userDao.updateUserPartial(
      UsersCompanion(
        id: drift.Value(user.id!),
        userSettings: drift.Value(jsonEncode(settings.toJson())),
        updatedAt: drift.Value(DateTime.now()),
      ),
    );
  }

  /// Добавить статистику теста
  Future<void> addTestStatistics(UserModel user, TestStatisticsDto testStat) async {
    if (user.id == null) {
      throw Exception('User ID is required');
    }

    // Получить или создать UserData
    var userData = await _db.userDao.getUserData(user.id!);
    if (userData == null) {
      await _db.userDao.createUserData(
        UserDatasCompanion.insert(userId: user.id!),
      );
      userData = await _db.userDao.getUserData(user.id!);
      if (userData == null) {
        throw Exception('Failed to create user data');
      }
    }

    // Проверить, не был ли этот sessionToken уже обработан
    if (userData.lastTestSessionToken == testStat.sessionToken) {
      log('Old session token, skipping');
      return;
    }

    // Получить или создать TestStatistic
    final existingStat = await _db.testDao.getTestStatistics(user.id!, testStat.testId);

    // Обновить результаты теста
    // results хранится как Map<String, dynamic>, где ключ 'attempts' содержит список попыток
    final currentResults = existingStat?.results ?? <String, dynamic>{};
    final attemptsKey = 'attempts';
    final currentAttempts = (currentResults[attemptsKey] as List<dynamic>?) ?? [];
    
    final newAttempt = <String, dynamic>{
      'sessionToken': testStat.sessionToken,
      'words': testStat.words.words.map((w) => w.toJson()).toList(),
    };
    
    final updatedAttempts = <dynamic>[...currentAttempts, newAttempt];
    final updatedResults = <String, dynamic>{
      ...currentResults,
      attemptsKey: updatedAttempts,
    };

    if (existingStat != null) {
      // Обновить существующую статистику
      final updatedStat = existingStat.copyWith(
        results: drift.Value(updatedResults),
        updatedAt: DateTime.now(),
      );
      await _db.testDao.updateTestStatistics(updatedStat);
    } else {
      // Создать новую статистику
      await _db.testDao.createTestStatistics(
        TestStatisticsCompanion.insert(
          userId: user.id!,
          testId: testStat.testId,
          results: drift.Value(updatedResults),
          completedAt: drift.Value(DateTime.now()),
        ),
      );
    }

    // Обновить статистику пользователя
    final now = DateTime.now();
    final todayNormalized = DateTime(now.year, now.month, now.day);
    final studyDates = List<DateTime>.from(userData.studyDates ?? []);

    // Добавить сегодняшнюю дату если еще нет
    if (!studyDates.any((date) =>
        date.year == todayNormalized.year &&
        date.month == todayNormalized.month &&
        date.day == todayNormalized.day)) {
      studyDates.add(todayNormalized);
    }

    // Пересчитать streak
    final currentStreak = _statisticsCalculator.calculateStreak(studyDates);
    final longestStreak = math.max(userData.longestStreak, currentStreak);

    // Обновить UserData
    await _db.userDao.updateUserDataPartial(
      UserDatasCompanion(
        userId: drift.Value(user.id!),
        lastTestSessionToken: drift.Value(testStat.sessionToken),
        studyDates: drift.Value(studyDates),
        currentStreak: drift.Value(currentStreak),
        longestStreak: drift.Value(longestStreak),
        lastTimeOnline: drift.Value(now),
        updatedAt: drift.Value(now),
      ),
    );
  }
}