import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_localizations/flutter_localizations.dart';

import '../core/auth/session_store.dart';
import '../core/localization/system_locale.dart';
import '../core/logging/logger.dart';
import '../core/timezone/system_timezone.dart';
import '../data/network/api_client.dart';
import '../data/storage/local_kv_store.dart';
import '../features/auth/data/apis/auth_api.dart';
import '../features/auth/data/repositories/auth_repository.dart';
import '../features/auth/presentation/bloc/auth_bloc.dart';
import '../features/auth/presentation/bloc/auth_state.dart';
import '../features/auth/presentation/screens/login_screen.dart';
import '../features/divination/data/apis/divination_api.dart';
import '../features/divination/data/models/divination_result.dart';
import '../features/home/presentation/screens/home_screen.dart';
import '../features/notifications/data/apis/notification_api.dart';
import '../features/notifications/data/repositories/notification_repository.dart';
import '../features/notifications/presentation/bloc/notification_bloc.dart';
import '../features/settings/data/apis/profile_api.dart';
import '../features/settings/data/models/profile_settings.dart';
import '../l10n/app_localizations.dart';
import '../shared/widgets/app_loading_indicator.dart';
import 'app_theme.dart';
import 'di/injection.dart';

class EryaoApp extends StatefulWidget {
  const EryaoApp({super.key});

  @override
  State<EryaoApp> createState() => _EryaoAppState();
}

class _EryaoAppState extends State<EryaoApp> {
  static final Logger _logger = getLogger('app.eryao_app');
  final SessionStore _sessionStore = SessionStore(LocalKvStore());
  late final AuthBloc _authBloc;
  late final DivinationApi _divinationApi;
  late final ProfileApi _profileApi;
  late final NotificationApi _notificationApi;
  late final NotificationRepository _notificationRepository;
  late final NotificationBloc _notificationBloc;
  Locale _locale = const Locale('zh');
  String _timezone = 'Asia/Shanghai';
  ProfileSettingsV1 _profileSettings = ProfileSettingsV1.defaultsForLocale(
    const Locale('zh'),
  );
  int _creditsBalance = 0;
  bool _loadingCredits = false;
  String? _loadedCreditsUserEmail;
  bool _loadingHistory = false;
  String? _loadedHistoryUserEmail;
  List<DivinationResultData> _historyRecords = const <DivinationResultData>[];
  bool _loadingProfile = false;
  String? _loadedProfileUserEmail;
  String? _lastUnreadRefreshedUserId;

  @override
  void initState() {
    super.initState();
    final apiClient = ApiClient(
      baseUrl: appDependencies.backendUrl,
      tokenProvider: _sessionStore.getToken,
      onUnauthorized: () {
        return _authBloc.handleUnauthorized401();
      },
    );
    final authApi = AuthApi(apiClient: apiClient);
    _divinationApi = DivinationApi(apiClient: apiClient);
    _profileApi = ProfileApi(apiClient: apiClient);
    _notificationApi = NotificationApi(apiClient: apiClient);
    _notificationRepository = NotificationRepositoryImpl(
      notificationApi: _notificationApi,
    );
    _notificationBloc = NotificationBloc(repository: _notificationRepository);
    final authRepository = AuthRepositoryImpl(
      authApi: authApi,
      sessionStore: _sessionStore,
    );
    _authBloc = AuthBloc(repository: authRepository);
    _authBloc.addListener(_onAuthStateChanged);
    _bootstrap();
  }

  void _onAuthStateChanged() {
    final state = _authBloc.state;
    if (state.status == AuthStatus.authenticated && state.user != null) {
      final userId = state.user!.id;
      if (_lastUnreadRefreshedUserId != userId) {
        _lastUnreadRefreshedUserId = userId;
        _notificationBloc.handleEvent(RefreshUnreadCount());
      }
      return;
    }
    _lastUnreadRefreshedUserId = null;
  }

  void _ensureCreditsLoaded(String userEmail) {
    if (_loadingCredits) {
      return;
    }
    if (_loadedCreditsUserEmail == userEmail) {
      return;
    }
    _loadingCredits = true;
    _refreshCredits(userEmail: userEmail).whenComplete(() {
      _loadingCredits = false;
    });
  }

  void _ensureHistoryLoaded(String userEmail) {
    if (_loadingHistory) {
      return;
    }
    if (_loadedHistoryUserEmail == userEmail) {
      return;
    }
    _loadingHistory = true;
    _divinationApi
        .getHistoryRecords(userId: userEmail)
        .then((records) {
          if (!mounted) {
            return;
          }
          setState(() {
            _historyRecords = records;
            _loadedHistoryUserEmail = userEmail;
          });
        })
        .catchError((Object error, StackTrace stackTrace) {
          _logger.warning(
            message: 'Failed to load divination history',
            extra: <String, dynamic>{
              'error': error.toString(),
              'stackTrace': stackTrace.toString(),
            },
          );
        })
        .whenComplete(() {
          _loadingHistory = false;
        });
  }

  Future<void> _refreshCredits({required String userEmail}) async {
    final balance = await _divinationApi.getPointsBalance();
    if (!mounted) {
      return;
    }
    setState(() {
      _creditsBalance = balance.availableBalance;
      _loadedCreditsUserEmail = userEmail;
    });
  }

  Future<void> _handleDivinationCompleted(DivinationResultData result) async {
    final user = _authBloc.state.user;
    if (user == null) {
      return;
    }

    final optimisticRecords = _mergeAndSortHistory(<DivinationResultData>[
      result,
      ..._historyRecords,
    ]);

    if (!mounted) {
      return;
    }

    setState(() {
      _historyRecords = optimisticRecords;
      _loadedHistoryUserEmail = user.email;
    });

    try {
      final records = await _divinationApi.getHistoryRecords(
        userId: user.email,
      );
      if (!mounted) {
        return;
      }
      setState(() {
        _historyRecords = _mergeAndSortHistory(<DivinationResultData>[
          ...records,
          ...optimisticRecords,
        ]);
        _loadedHistoryUserEmail = user.email;
      });
    } catch (error, stackTrace) {
      _logger.warning(
        message: 'Failed to refresh history after divination completion',
        extra: <String, dynamic>{
          'error': error.toString(),
          'stackTrace': stackTrace.toString(),
        },
      );
    }

    try {
      await _refreshCredits(userEmail: user.email);
    } catch (error, stackTrace) {
      _logger.warning(
        message: 'Failed to refresh credits after divination completion',
        extra: <String, dynamic>{
          'error': error.toString(),
          'stackTrace': stackTrace.toString(),
        },
      );
    }
  }

  Future<void> _handleHistorySessionDeleted(String threadId) async {
    final user = _authBloc.state.user;
    if (user == null) {
      return;
    }

    final rollback = List<DivinationResultData>.from(_historyRecords);
    if (!mounted) {
      return;
    }
    setState(() {
      _historyRecords = _historyRecords
          .where((item) => item.threadId != threadId)
          .toList(growable: false);
      _loadedHistoryUserEmail = user.email;
    });

    unawaited(
      _deleteHistorySessionRemote(
        threadId: threadId,
        userEmail: user.email,
        rollback: rollback,
      ),
    );
  }

  Future<void> _deleteHistorySessionRemote({
    required String threadId,
    required String userEmail,
    required List<DivinationResultData> rollback,
  }) async {
    try {
      await _divinationApi.deleteSession(threadId: threadId);
    } catch (error, stackTrace) {
      _logger.error(
        message: 'Failed to delete history session',
        error: error,
        stackTrace: stackTrace,
        extra: <String, dynamic>{'threadId': threadId},
      );
      if (!mounted) {
        return;
      }
      setState(() {
        _historyRecords = rollback;
        _loadedHistoryUserEmail = userEmail;
      });
    }
  }

  List<DivinationResultData> _mergeAndSortHistory(
    List<DivinationResultData> input,
  ) {
    final seen = <String>{};
    final deduped = <DivinationResultData>[];
    for (final item in input) {
      final key = _historyKey(item);
      if (seen.add(key)) {
        deduped.add(item);
      }
    }
    deduped.sort(
      (a, b) => b.params.divinationTime.compareTo(a.params.divinationTime),
    );
    return deduped;
  }

  String _historyKey(DivinationResultData item) {
    return [
      item.params.question,
      item.binaryCode,
      item.changedBinaryCode,
      item.guaName,
      item.targetGuaName,
      item.signType,
    ].join('|');
  }

  Future<void> _refreshProfile({required String userEmail}) async {
    if (_loadingProfile) {
      return;
    }
    if (_loadedProfileUserEmail == userEmail) {
      return;
    }
    _loadingProfile = true;
    try {
      final profile = await _profileApi.getProfile();
      if (!mounted) {
        return;
      }
      final serverLanguage = profile.preferences.language;
      final serverTimezone = profile.preferences.timezone;
      final serverLocale = localeFromLanguageTag(serverLanguage);
      await _sessionStore.saveLocaleTag(serverLanguage);
      await _sessionStore.saveTimezone(serverTimezone);
      setState(() {
        _locale = serverLocale;
        _timezone = serverTimezone;
        _profileSettings = profile;
        _loadedProfileUserEmail = userEmail;
      });
    } finally {
      _loadingProfile = false;
    }
  }

  Future<ProfileSettingsV1> _uploadAvatar(String filePath) async {
    final updated = await _profileApi.uploadAvatar(filePath);
    if (!mounted) {
      return updated;
    }
    setState(() {
      _profileSettings = updated;
    });
    return updated;
  }

  Future<ProfileSettingsV1> _saveProfile(ProfileSettingsV1 updated) async {
    final saved = await _profileApi.updateSettings(updated);
    if (!mounted) {
      return saved;
    }
    setState(() {
      _profileSettings = saved;
    });
    return saved;
  }

  Future<void> _deleteAccount() async {
    await _profileApi.deleteAccount();
    if (!mounted) {
      return;
    }
    setState(() {
      _profileSettings = ProfileSettingsV1.defaultsForLocale(_locale);
      _historyRecords = const <DivinationResultData>[];
      _creditsBalance = 0;
      _loadedProfileUserEmail = null;
      _loadedHistoryUserEmail = null;
      _loadedCreditsUserEmail = null;
    });
  }

  Future<void> _saveProfileSettings(ProfileSettingsV1 next) async {
    try {
      final oldLanguage = _profileSettings.preferences.language;
      final newLanguage = next.preferences.language;
      final saved = await _profileApi.updateSettings(next);
      if (!mounted) {
        return;
      }
      setState(() {
        _profileSettings = saved;
      });
      if (oldLanguage != newLanguage) {
        await _handleInterfaceLanguageChanged(newLanguage);
      }
    } catch (error, stackTrace) {
      _logger.error(
        message: 'Failed to save profile settings via API',
        error: error,
        stackTrace: stackTrace,
      );
      rethrow;
    }
  }

  @override
  void dispose() {
    _authBloc.removeListener(_onAuthStateChanged);
    _authBloc.dispose();
    _notificationBloc.dispose();
    super.dispose();
  }

  Future<void> _bootstrap() async {
    final savedLocaleTag = await _sessionStore.getLocaleTag();
    final Locale locale;
    if (savedLocaleTag != null) {
      locale = localeFromLanguageTag(savedLocaleTag);
    } else {
      final systemLocale = getSystemLocale();
      locale = resolveSystemLocale(systemLocale) ?? const Locale('zh');
      await _sessionStore.saveLocaleTag(languageTagFromLocale(locale));
    }

    final savedTimezone = await _sessionStore.getTimezone();
    final String timezone;
    if (savedTimezone != null) {
      timezone = savedTimezone;
    } else {
      timezone = await getSystemTimezone();
      await _sessionStore.saveTimezone(timezone);
    }

    if (mounted) {
      setState(() {
        _locale = locale;
        _timezone = timezone;
        _profileSettings = ProfileSettingsV1.defaultsForLocale(locale);
      });
    }
    await _authBloc.start();
  }

  Future<void> _handleInterfaceLanguageChanged(String languageTag) async {
    final locale = localeFromLanguageTag(languageTag);
    await _sessionStore.saveLocaleTag(languageTag);
    if (!mounted) {
      return;
    }
    setState(() {
      _locale = locale;
      _profileSettings = _profileSettings.copyWith(
        preferences: _profileSettings.preferences.copyWith(
          language: languageTag,
        ),
      );
    });
  }

  void _handleBalanceChanged(int newBalance) {
    if (!mounted) {
      return;
    }
    setState(() {
      _creditsBalance = newBalance;
    });
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _authBloc,
      builder: (context, _) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          onGenerateTitle: (context) => AppLocalizations.of(context)!.appTitle,
          locale: _locale,
          localizationsDelegates: const [
            AppLocalizations.delegate,
            GlobalMaterialLocalizations.delegate,
            GlobalWidgetsLocalizations.delegate,
            GlobalCupertinoLocalizations.delegate,
          ],
          supportedLocales: AppLocalizations.supportedLocales,
          theme: AppTheme.light(),
          home: _buildHomeByAuthState(_authBloc.state),
        );
      },
    );
  }

  Widget _buildHomeByAuthState(AuthState state) {
    if (state.status == AuthStatus.initial ||
        state.status == AuthStatus.loading) {
      return const Scaffold(
        body: Center(
          child: AppLoadingIndicator(variant: AppLoadingVariant.surface),
        ),
      );
    }

    if (state.status == AuthStatus.authenticated && state.user != null) {
      _ensureCreditsLoaded(state.user!.email);
      _ensureHistoryLoaded(state.user!.email);
      _refreshProfile(userEmail: state.user!.email);
      return HomeScreen(
        account: state.user!.email,
        userId: state.user!.id,
        sessionStore: _sessionStore,
        currentLocale: _locale,
        profileSettings: _profileSettings,
        historyRecords: _historyRecords,
        coinBalance: _creditsBalance,
        divinationApi: _divinationApi,
        notificationBloc: _notificationBloc,
        notificationRepository: _notificationRepository,
        onLocaleChanged: _handleInterfaceLanguageChanged,
        onProfileSettingsChanged: _saveProfileSettings,
        onSaveProfile: _saveProfile,
        onUploadAvatar: _uploadAvatar,
        onDivinationCompleted: _handleDivinationCompleted,
        onDeleteHistorySession: _handleHistorySessionDeleted,
        onLogout: _authBloc.logout,
        onDeleteAccount: _deleteAccount,
        onBalanceChanged: _handleBalanceChanged,
      );
    }

    return LoginScreen(
      currentLocale: _locale,
      onLocaleChanged: (_) {},
      onRequestOtp: _authBloc.sendOtp,
      onLoginWithOtp: (email, otp) {
        return _authBloc.loginWithOtp(
          email: email,
          otp: otp,
          language: languageTagFromLocale(_locale),
          timezone: _timezone,
        );
      },
    );
  }
}