import 'dart:async';
import 'package:flutter_bloc/flutter_bloc.dart';
import '../data/models/trip_model.dart';
import '../data/trip_repository.dart';
import '../data/trip_socket_service.dart';
import '../data/trip_event_merger.dart';
import 'trip_event.dart';
import 'trip_state.dart';

/// TripBloc — Bloc الوحيد للراكب (docs/03 §14).
///
/// يتعامل مع Lifecycle كامل: إنشاء → تتبّع → إتمام → تقييم.
/// المصادر الثلاث: أحداث المستخدم، WebSocket، FCM — تمر عبر TripEventMerger.
class TripBloc extends Bloc<TripEvent, TripState> {
  final TripRepository _tripRepo;
  final TripSocketService _socket;
  final TripEventMerger _merger;
  Timer? _reconciliationTimer;

  TripBloc({
    required TripRepository tripRepo,
    required TripSocketService socket,
    TripEventMerger? merger,
  })  : _tripRepo = tripRepo,
        _socket = socket,
        _merger = merger ?? TripEventMerger(),
        super(const TripState()) {
    on<TripCheckActive>(_onCheckActive);
    on<TripRequested>(_onRequested);
    on<TripUpdateReceived>(_onUpdateReceived);
    on<TripDriverLocation>(_onDriverLocation);
    on<TripCancelRequested>(_onCancel);
    on<TripRetry>(_onRetry);
    on<TripRate>(_onRate);
    on<TripClear>(_onClear);

    // استمع لتحديثات TripEventMerger.
    _merger.updateStream.listen((update) {
      add(TripUpdateReceived(
        tripId: update.tripId,
        status: update.status,
        driverId: update.driverId,
        extra: update.extra,
      ));
    });

    _merger.locationStream.listen((loc) {
      add(TripDriverLocation(
        tripId: loc.tripId,
        lat: loc.lat,
        lng: loc.lng,
        heading: loc.heading,
        speed: loc.speed,
      ));
    });

    // اتصل بالـWebSocket.
    _socket.connect();
  }

  /// فحص رحلة نشطة عند بدء التشغيل أو العودة من الخلفية.
  Future<void> _onCheckActive(TripCheckActive event, Emitter<TripState> emit) async {
    try {
      final trip = await _tripRepo.getActiveTrip();
      if (trip != null) {
        emit(state.copyWith(
          requestStatus: _statusFromTrip(trip.status),
          trip: trip,
        ));
        _joinTripRoom(trip.id);
        _startReconciliation(trip.id);
      }
    } catch (_) {
      // خطأ صامت — سنحاول مرة أخرى عند إعادة الاتصال.
    }
  }

  /// طلب رحلة جديدة.
  Future<void> _onRequested(TripRequested event, Emitter<TripState> emit) async {
    emit(state.copyWith(requestStatus: TripRequestStatus.loading, clearError: true));
    try {
      final trip = await _tripRepo.createTrip(
        pickupLat: event.pickupLat,
        pickupLng: event.pickupLng,
        pickupAddress: event.pickupAddress,
        dropoffLat: event.dropoffLat,
        dropoffLng: event.dropoffLng,
        dropoffAddress: event.dropoffAddress,
        vehicleClass: event.vehicleClass,
        paymentMethod: event.paymentMethod,
        couponCode: event.couponCode,
      );
      emit(state.copyWith(
        requestStatus: TripRequestStatus.searching,
        trip: trip,
      ));
      _joinTripRoom(trip.id);
      _startReconciliation(trip.id);
    } catch (e) {
      emit(state.copyWith(
        requestStatus: TripRequestStatus.error,
        error: e.toString(),
      ));
    }
  }

  /// تحديث حالة الرحلة — من WebSocket أو FCM عبر TripEventMerger.
  void _onUpdateReceived(TripUpdateReceived event, Emitter<TripState> emit) {
    final currentTrip = state.trip;
    if (currentTrip == null || currentTrip.id != event.tripId) return;

    // التصفية الصامتة: تجاهل الأحداث القديمة.
    final currentOrder = statusOrder(currentTrip.status);
    final newOrder = statusOrder(event.status);
    if (newOrder >= 0 && newOrder <= currentOrder) return;

    // تحديث النموذج محلياً.
    final updatedTrip = TripModel(
      id: currentTrip.id,
      status: event.status,
      clientId: currentTrip.clientId,
      pickupLat: currentTrip.pickupLat,
      pickupLng: currentTrip.pickupLng,
      pickupAddress: currentTrip.pickupAddress,
      dropoffLat: currentTrip.dropoffLat,
      dropoffLng: currentTrip.dropoffLng,
      dropoffAddress: currentTrip.dropoffAddress,
      vehicleClass: currentTrip.vehicleClass,
      fare: (event.extra['fare'] as num?) ?? currentTrip.fare,
      currency: event.extra['currency'] as String? ?? currentTrip.currency,
      paymentMethod: currentTrip.paymentMethod,
      driverId: event.driverId ?? currentTrip.driverId,
      createdAt: currentTrip.createdAt,
      updatedAt: DateTime.now(),
    );

    final newStatus = _statusFromTrip(event.status);

    // استخراج معلومات السائق من extra.
    final vehicle = event.extra['vehicle'] as Map<String, dynamic>?;

    emit(state.copyWith(
      requestStatus: newStatus,
      trip: updatedTrip,
      driverName: event.extra['driverName'] as String?,
      vehicleMake: vehicle?['make'] as String?,
      vehicleModel: vehicle?['model'] as String?,
      vehiclePlate: vehicle?['plate'] as String?,
      vehicleColor: vehicle?['color'] as String?,
    ));

    // حالة نهائية: أوقف مؤقت الم reconciliation.
    if (isTerminalStatus(event.status)) {
      _stopReconciliation();
      _socket.leaveTrip(event.tripId);
    }
  }

  /// موقع السائق الحي.
  void _onDriverLocation(TripDriverLocation event, Emitter<TripState> emit) {
    if (state.trip?.id != event.tripId) return;
    emit(state.copyWith(
      driverLat: event.lat,
      driverLng: event.lng,
      driverHeading: event.heading,
    ));
  }

  /// إلغاء الرحلة.
  Future<void> _onCancel(TripCancelRequested event, Emitter<TripState> emit) async {
    if (state.trip == null) return;
    try {
      final trip = await _tripRepo.cancelTrip(state.trip!.id);
      _stopReconciliation();
      _socket.leaveTrip(state.trip!.id);
      emit(state.copyWith(
        requestStatus: TripRequestStatus.completed,
        trip: trip,
      ));
    } catch (e) {
      emit(state.copyWith(error: e.toString()));
    }
  }

  /// إعادة المحاولة بعد خطأ.
  void _onRetry(TripRetry event, Emitter<TripState> emit) {
    emit(state.copyWith(requestStatus: TripRequestStatus.idle, clearError: true));
  }

  /// تقييم الرحلة.
  Future<void> _onRate(TripRate event, Emitter<TripState> emit) async {
    if (state.trip == null) return;
    try {
      await _tripRepo.rateTrip(state.trip!.id, stars: event.stars, comment: event.comment);
      emit(state.copyWith(rated: true));
    } catch (e) {
      emit(state.copyWith(error: e.toString()));
    }
  }

  /// مسح الرحلة من الذاكرة.
  void _onClear(TripClear event, Emitter<TripState> emit) {
    _stopReconciliation();
    emit(const TripState());
  }

  // --- مساعدات ---

  void _joinTripRoom(String tripId) {
    _socket.joinTrip(tripId);
  }

  void _startReconciliation(String tripId) {
    _stopReconciliation();
    _reconciliationTimer = Timer.periodic(const Duration(seconds: 25), (_) async {
      try {
        final trip = await _tripRepo.getTrip(tripId);
        if (trip != null) {
          add(TripUpdateReceived(
            tripId: trip.id,
            status: trip.status,
            driverId: trip.driverId,
            extra: {
              if (trip.fare != null) 'fare': trip.fare,
              if (trip.currency != null) 'currency': trip.currency,
            },
          ));
        }
      } catch (_) {
        // خطأ صامت — سيحاول مرة أخرى.
      }
    });
  }

  void _stopReconciliation() {
    _reconciliationTimer?.cancel();
    _reconciliationTimer = null;
  }

  TripRequestStatus _statusFromTrip(String status) {
    switch (status) {
      case 'searching':
        return TripRequestStatus.searching;
      case 'assigned':
      case 'driver_arriving':
      case 'driver_arrived':
      case 'in_progress':
        return TripRequestStatus.active;
      case 'completed':
      case 'paid':
        return TripRequestStatus.completed;
      case 'cancelled':
      case 'no_drivers':
      case 'expired':
        return TripRequestStatus.completed;
      default:
        return TripRequestStatus.searching;
    }
  }

  @override
  Future<void> close() {
    _stopReconciliation();
    _merger.dispose();
    _socket.disconnect();
    return super.close();
  }
}