import 'dart:async';

import 'package:equatable/equatable.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:uto_manager/domain/entities/personnel_record.dart';
import 'package:uto_manager/domain/entities/position_slot.dart';
import 'package:uto_manager/domain/repositories/personnel_repository.dart';
import 'package:uto_manager/domain/services/assignment_service.dart';
import 'package:uto_manager/infrastructure/repositories/drift_position_slot_repository.dart';

// ---------------------------------------------------------------------------
// State
// ---------------------------------------------------------------------------

/// State for the personnel cubit.
sealed class PersonnelState extends Equatable {
  const PersonnelState();
}

class PersonnelInitial extends PersonnelState {
  const PersonnelInitial();

  @override
  List<Object?> get props => [];
}

class PersonnelLoading extends PersonnelState {
  const PersonnelLoading();

  @override
  List<Object?> get props => [];
}

class PersonnelLoaded extends PersonnelState {
  const PersonnelLoaded({
    required this.allPersonnel,
    required this.unassigned,
    this.filterQuery = '',
  });

  /// All personnel records.
  final List<PersonnelRecord> allPersonnel;

  /// Unassigned soldiers (available for assignment).
  final List<PersonnelRecord> unassigned;

  /// Current search/filter query string.
  final String filterQuery;

  /// Returns [unassigned] filtered by [filterQuery].
  List<PersonnelRecord> get filteredUnassigned {
    if (filterQuery.isEmpty) return unassigned;
    final q = filterQuery.toLowerCase();
    return unassigned.where((p) {
      return p.name.toLowerCase().contains(q) ||
          p.primaryMos.code.toLowerCase().contains(q) ||
          p.payGrade.payGrade.toLowerCase().contains(q);
    }).toList();
  }

  PersonnelLoaded copyWith({
    List<PersonnelRecord>? allPersonnel,
    List<PersonnelRecord>? unassigned,
    String? filterQuery,
  }) {
    return PersonnelLoaded(
      allPersonnel: allPersonnel ?? this.allPersonnel,
      unassigned: unassigned ?? this.unassigned,
      filterQuery: filterQuery ?? this.filterQuery,
    );
  }

  @override
  List<Object?> get props => [allPersonnel, unassigned, filterQuery];
}

class PersonnelError extends PersonnelState {
  const PersonnelError(this.message);

  final String message;

  @override
  List<Object?> get props => [message];
}

// ---------------------------------------------------------------------------
// Cubit
// ---------------------------------------------------------------------------

/// Manages personnel state, including loading, filtering, and assignment.
class PersonnelCubit extends Cubit<PersonnelState> {
  PersonnelCubit({
    required this.personnelRepository,
    required this.slotRepository,
    required this.assignmentService,
  }) : super(const PersonnelInitial());

  final PersonnelRepository personnelRepository;
  final DriftPositionSlotRepository slotRepository;
  final AssignmentService assignmentService;

  StreamSubscription<List<PersonnelRecord>>? _allSubscription;
  StreamSubscription<List<PersonnelRecord>>? _unassignedSubscription;

  List<PersonnelRecord> _all = [];
  List<PersonnelRecord> _unassigned = [];

  // ---------------------------------------------------------------------------
  // Lifecycle
  // ---------------------------------------------------------------------------

  /// Starts watching the database for personnel changes.
  void startWatching() {
    emit(const PersonnelLoading());

    _allSubscription = personnelRepository.watchAll().listen(
      (all) {
        _all = all;
        _rebuild();
      },
      onError: (Object e) => emit(PersonnelError(e.toString())),
    );

    _unassignedSubscription = personnelRepository.watchUnassigned().listen(
      (unassigned) {
        _unassigned = unassigned;
        _rebuild();
      },
      onError: (Object e) => emit(PersonnelError(e.toString())),
    );
  }

  void _rebuild() {
    final currentFilter = state is PersonnelLoaded ? (state as PersonnelLoaded).filterQuery : '';
    emit(PersonnelLoaded(allPersonnel: _all, unassigned: _unassigned, filterQuery: currentFilter));
  }

  // ---------------------------------------------------------------------------
  // Filtering
  // ---------------------------------------------------------------------------

  /// Updates the search filter query.
  void setFilter(String query) {
    if (state is PersonnelLoaded) {
      emit((state as PersonnelLoaded).copyWith(filterQuery: query));
    }
  }

  // ---------------------------------------------------------------------------
  // Assignment
  // ---------------------------------------------------------------------------

  /// Assigns [soldier] to [slot] after validation.
  ///
  /// Returns true on success, false if validation failed.
  Future<bool> assignSoldierToSlot(PersonnelRecord soldier, PositionSlot slot) async {
    final outcome = assignmentService.assign(slot, soldier);
    if (!outcome.isSuccess) return false;

    try {
      await personnelRepository.assignToSlot(soldier.soldierId, slot.slotId);
      await slotRepository.assignPersonnel(slot.slotId, soldier.soldierId);
      return true;
    } catch (e) {
      emit(PersonnelError(e.toString()));
      return false;
    }
  }

  /// Unassigns the soldier from [slot].
  Future<void> unassignFromSlot(PositionSlot slot) async {
    if (slot.isVacant) return;
    try {
      await personnelRepository.unassignFromSlot(slot.assignedPersonnelId!);
      await slotRepository.clearAssignment(slot.slotId);
    } catch (e) {
      emit(PersonnelError(e.toString()));
    }
  }

  /// Adds a new [record] to the personnel roster.
  Future<void> addPersonnel(PersonnelRecord record) async {
    try {
      await personnelRepository.insert(record);
    } catch (e) {
      emit(PersonnelError(e.toString()));
    }
  }

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