import 'dart:async';
import 'package:equatable/equatable.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import '../data/offers_repository.dart';
import 'package:driver/features/home/data/models/trip_offer_model.dart';
import '../../trip/data/driver_socket_service.dart';
import '../../trip/data/trip_event_merger.dart';

// ─── أحداث ───

sealed class OffersEvent extends Equatable {
  const OffersEvent();
  @override
  List<Object?> get props => [];
}

/// بدء الاستماع للعروض (بعد الاتصال بالـWebSocket).
class OffersStarted extends OffersEvent {
  const OffersStarted();
}

/// عرض رحلة وارد (من WebSocket).
class OfferReceived extends OffersEvent {
  final TripOfferModel offer;
  const OfferReceived(this.offer);
  @override
  List<Object?> get props => [offer.tripId];
}

/// العرض تم قبوله من سائق آخر.
class OfferTaken extends OffersEvent {
  final String tripId;
  const OfferTaken(this.tripId);
  @override
  List<Object?> get props => [tripId];
}

/// العرض انتهت مهلته (من المؤقت).
class OfferExpired extends OffersEvent {
  final String tripId;
  const OfferExpired(this.tripId);
  @override
  List<Object?> get props => [tripId];
}

/// قبول العرض.
class OfferAccepted extends OffersEvent {
  final String tripId;
  const OfferAccepted(this.tripId);
  @override
  List<Object?> get props => [tripId];
}

/// رفض العرض يدوياً.
class OfferRejected extends OffersEvent {
  final String tripId;
  const OfferRejected(this.tripId);
  @override
  List<Object?> get props => [tripId];
}

/// مسح كل العروض (عند بدء رحلة نشطة).
class OffersClear extends OffersEvent {
  const OffersClear();
}

// ─── حالة ───

class OffersState extends Equatable {
  final List<TripOfferModel> offers;
  final String? acceptedTripId;
  final bool accepting;
  final String? error;

  const OffersState({
    this.offers = const [],
    this.acceptedTripId,
    this.accepting = false,
    this.error,
  });

  OffersState copyWith({
    List<TripOfferModel>? offers,
    String? acceptedTripId,
    bool? accepting,
    String? error,
    bool clearError = false,
    bool clearAccepted = false,
  }) {
    return OffersState(
      offers: offers ?? this.offers,
      acceptedTripId: clearAccepted ? null : (acceptedTripId ?? this.acceptedTripId),
      accepting: accepting ?? this.accepting,
      error: clearError ? null : (error ?? this.error),
    );
  }

  /// هل هناك عرض واحد على الأقل؟
  bool get hasOffers => offers.isNotEmpty;

  @override
  List<Object?> get props => [offers, acceptedTripId, accepting, error];
}

// ─── Bloc ───

/// OffersBloc — Bloc الثاني للسائق (docs/03 §14).
///
/// يستقبل عروض من WebSocket ويدير القبول/الرفض والمؤقت.
/// العروض تُعرض كـstack: الأحدث أولاً.
class OffersBloc extends Bloc<OffersEvent, OffersState> {
  final OffersRepository _offersRepo;
  final DriverSocketService _socket;
  final DriverTripEventMerger _merger;

  /// مؤقتات المهلة لكل عرض ( tripId → Timer ).
  final Map<String, Timer> _expiryTimers = {};

  OffersBloc({
    required OffersRepository offersRepo,
    required DriverSocketService socket,
    DriverTripEventMerger? merger,
  })  : _offersRepo = offersRepo,
        _socket = socket,
        _merger = merger ?? DriverTripEventMerger(),
        super(const OffersState()) {
    on<OffersStarted>(_onStarted);
    on<OfferReceived>(_onOfferReceived);
    on<OfferTaken>(_onOfferTaken);
    on<OfferExpired>(_onOfferExpired);
    on<OfferAccepted>(_onOfferAccepted);
    on<OfferRejected>(_onOfferRejected);
    on<OffersClear>(_onClear);

    // استمع لتحديثات Merger.
    _merger.offerStream.listen((offer) {
      add(OfferReceived(offer));
    });

    _merger.offerTakenStream.listen((tripId) {
      add(OfferTaken(tripId));
    });
  }

  Future<void> _onStarted(OffersStarted event, Emitter<OffersState> emit) async {
    _socket.connect();
  }

  void _onOfferReceived(OfferReceived event, Emitter<OffersState> emit) {
    // لا تضف عروضاً مكررة.
    final exists = state.offers.any((o) => o.tripId == event.offer.tripId);
    if (exists) return;

    final updated = [event.offer, ...state.offers];
    emit(state.copyWith(offers: updated, clearError: true));

    // ابدأ مؤقت المهلة.
    _startExpiryTimer(event.offer);
  }

  void _onOfferTaken(OfferTaken event, Emitter<OffersState> emit) {
    final updated = state.offers.where((o) => o.tripId != event.tripId).toList();
    _cancelExpiryTimer(event.tripId);
    emit(state.copyWith(offers: updated));
  }

  void _onOfferExpired(OfferExpired event, Emitter<OffersState> emit) {
    final updated = state.offers.where((o) => o.tripId != event.tripId).toList();
    _cancelExpiryTimer(event.tripId);
    emit(state.copyWith(offers: updated));
  }

  Future<void> _onOfferAccepted(OfferAccepted event, Emitter<OffersState> emit) async {
    emit(state.copyWith(accepting: true, clearError: true));

    final trip = await _offersRepo.acceptTrip(event.tripId);
    if (trip == null) {
      emit(state.copyWith(accepting: false, error: 'Failed to accept trip'));
      return;
    }

    // أزل كل العروض المتبقية (تم اختيار سائق).
    _cancelAllTimers();
    emit(state.copyWith(
      offers: [],
      accepting: false,
      acceptedTripId: event.tripId,
    ));
  }

  void _onOfferRejected(OfferRejected event, Emitter<OffersState> emit) {
    final updated = state.offers.where((o) => o.tripId != event.tripId).toList();
    _cancelExpiryTimer(event.tripId);
    emit(state.copyWith(offers: updated));
  }

  void _onClear(OffersClear event, Emitter<OffersState> emit) {
    _cancelAllTimers();
    emit(const OffersState());
  }

  // ─── مساعدات المؤقتات ───

  void _startExpiryTimer(TripOfferModel offer) {
    final remaining = offer.expiresAt.difference(DateTime.now());
    if (remaining.isNegative) {
      add(OfferExpired(offer.tripId));
      return;
    }

    _expiryTimers[offer.tripId]?.cancel();
    _expiryTimers[offer.tripId] = Timer(remaining, () {
      add(OfferExpired(offer.tripId));
    });
  }

  void _cancelExpiryTimer(String tripId) {
    _expiryTimers[tripId]?.cancel();
    _expiryTimers.remove(tripId);
  }

  void _cancelAllTimers() {
    for (final timer in _expiryTimers.values) {
      timer.cancel();
    }
    _expiryTimers.clear();
  }

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