import 'dart:async';

import 'package:flutter_bloc/flutter_bloc.dart';

import 'package:geolocator/geolocator.dart';
import 'package:permission_handler/permission_handler.dart';

import 'package:shared_preferences/shared_preferences.dart';

import '../../../core/api/api_exception.dart';

import '../../../core/api/api_failure.dart';

import '../../../core/config.dart';

import '../data/auth_repository.dart';

import 'login_state.dart';

import 'phone_error.dart';

/// تدفّق الدخول كاملاً: الشروط ← إذن الموقع ← الهاتف ← الرمز.
///
/// الـCubit لا يعرف Flutter: لا `BuildContext` ولا تنقّل ولا `SnackBar`
/// (docs/23 §3). يُصدر حالة، والواجهة تتصرّف.
class LoginCubit extends Cubit<LoginState> {
  LoginCubit(this._repo, this._prefs) : super(const LoginState()) {
    _resolveInitialStep();
  }

  final AuthRepository _repo;
  final SharedPreferences _prefs;

  static const _kAgreed = 'auth.agreed_terms';

  Timer? _resendTimer;

  @override
  Future<void> close() {
    _resendTimer?.cancel();
    return super.close();
  }

  // ── البوابتان ──────────────────────────────────────────────────────────

  void _resolveInitialStep() {
    if (_prefs.getBool(_kAgreed) != true) {
      emit(state.copyWith(step: LoginStep.agreement));
      return;
    }
    emit(state.copyWith(step: LoginStep.permission, agreed: true));
    unawaited(checkLocationPermission());
  }

  void toggleAgreement(bool value) => emit(state.copyWith(agreed: value));

  Future<void> acceptAgreement() async {
    if (!state.agreed) return;
    await _prefs.setBool(_kAgreed, true);
    emit(state.copyWith(step: LoginStep.permission));
    await checkLocationPermission();
  }

  /// تُستدعى أيضاً عند **العودة من إعدادات النظام**: بلا إعادة الفحص تبقى
  /// الشاشة عالقة بعد أن يمنح المستخدم الإذن يدوياً (حالة حافة من docs/39 §2).
  Future<void> checkLocationPermission() async {
    final geoStatus = await Geolocator.checkPermission();
    if (geoStatus == LocationPermission.always ||
        geoStatus == LocationPermission.whileInUse) {
      emit(state.copyWith(
        step: LoginStep.phone,
        permissionPermanentlyDenied: false,
      ));
      return;
    }

    final status = await Permission.locationWhenInUse.status;
    if (status.isGranted || status.isLimited) {
      emit(state.copyWith(
        step: LoginStep.phone,
        permissionPermanentlyDenied: false,
      ));
      return;
    }

    emit(state.copyWith(
      permissionPermanentlyDenied:
          geoStatus == LocationPermission.deniedForever ||
              status.isPermanentlyDenied,
    ));
  }

  Future<void> requestLocationPermission() async {
    final geoStatus = await Geolocator.requestPermission();
    if (geoStatus == LocationPermission.always ||
        geoStatus == LocationPermission.whileInUse) {
      emit(state.copyWith(
        step: LoginStep.phone,
        permissionPermanentlyDenied: false,
      ));
      return;
    }

    final status = await Permission.locationWhenInUse.request();
    if (status.isGranted || status.isLimited) {
      emit(state.copyWith(
        step: LoginStep.phone,
        permissionPermanentlyDenied: false,
      ));
      return;
    }

    emit(state.copyWith(
      permissionPermanentlyDenied:
          geoStatus == LocationPermission.deniedForever ||
              status.isPermanentlyDenied,
    ));
  }

  Future<void> openSystemSettings() => openAppSettings();

  // ── الهاتف ─────────────────────────────────────────────────────────────

  void phoneChanged(String value) {
    emit(state.copyWith(
      phone: value,
      clearPhoneError: true,
      clearFailure: true,
    ));
  }

  Future<void> submitPhone() async {
    final error = validatePhone(state.phone);
    if (error != null) {
      emit(state.copyWith(phoneError: error));
      return;
    }
    emit(state.copyWith(status: LoginStatus.submitting, clearFailure: true));
    try {
      await _repo.sendOtp(state.phone.trim());
      emit(state.copyWith(status: LoginStatus.idle, step: LoginStep.otp));
      _startResendCountdown();
    } on ApiException catch (e) {
      emit(state.copyWith(
        status: LoginStatus.failure,
        failure: e.toApiFailure(),
      ));
    }
  }

  void editPhone() {
    _resendTimer?.cancel();
    emit(state.copyWith(
      step: LoginStep.phone,
      status: LoginStatus.idle,
      resendIn: 0,
      clearFailure: true,
    ));
  }

  // ── الرمز ──────────────────────────────────────────────────────────────

  Future<void> resendOtp() async {
    if (!state.canResend) return;
    emit(state.copyWith(status: LoginStatus.submitting, clearFailure: true));
    try {
      await _repo.sendOtp(state.phone.trim());
      emit(state.copyWith(status: LoginStatus.idle));
      _startResendCountdown();
    } on ApiException catch (e) {
      emit(state.copyWith(
        status: LoginStatus.failure,
        failure: e.toApiFailure(),
      ));
      // حتى عند الرفض بحدّ المعدّل نبدأ العدّاد — وإلا ضغط المستخدم مجدداً
      // فوراً وعمّق الحظر.
      _startResendCountdown();
    }
  }

  Future<void> submitOtp(String code) async {
    if (code.length != AppConfig.otpLength) return;
    emit(state.copyWith(status: LoginStatus.submitting, clearFailure: true));
    try {
      final user = await _repo.verifyOtp(phone: state.phone.trim(), code: code);
      _resendTimer?.cancel();
      emit(state.copyWith(
        status: LoginStatus.success,
        step: LoginStep.done,
        user: user,
      ));
    } on ApiException catch (e) {
      emit(state.copyWith(
        status: LoginStatus.failure,
        failure: e.toApiFailure(),
      ));
    }
  }

  void _startResendCountdown() {
    _resendTimer?.cancel();
    emit(state.copyWith(resendIn: AppConfig.otpResendCooldown.inSeconds));
    _resendTimer = Timer.periodic(const Duration(seconds: 1), (timer) {
      final next = state.resendIn - 1;
      if (next <= 0) timer.cancel();
      emit(state.copyWith(resendIn: next < 0 ? 0 : next));
    });
  }
}