import 'dart:async' show unawaited, StreamController;

import 'package:dartz/dartz.dart';
import 'package:injectable/injectable.dart';
import 'package:superport/core/errors/failures.dart';
import 'package:superport/core/utils/debug_logger.dart';
import 'package:superport/data/datasources/remote/lookup_remote_datasource.dart';
import 'package:superport/data/models/lookups/lookup_data.dart';

/// 전역 Lookups 캐싱 서비스 (Singleton 패턴)
@LazySingleton()
class LookupsService {
  final LookupRemoteDataSource _dataSource;
  
  // 캐시된 데이터
  LookupData? _cachedData;
  DateTime? _lastUpdated;
  bool _isInitialized = false;
  bool _isLoading = false;
  
  // 캐시 만료 시간 (기본: 30분)
  static const Duration _cacheExpiry = Duration(minutes: 30);
  
  // 초기화 완료 스트림
  final StreamController<bool> _initializationController = StreamController<bool>.broadcast();
  
  LookupsService(this._dataSource);

  /// 초기화 상태 스트림
  Stream<bool> get initializationStream => _initializationController.stream;
  
  /// 초기화 여부
  bool get isInitialized => _isInitialized;
  
  /// 로딩 상태
  bool get isLoading => _isLoading;
  
  /// 캐시 만료 여부
  bool get _isCacheExpired {
    if (_lastUpdated == null) return true;
    return DateTime.now().difference(_lastUpdated!) > _cacheExpiry;
  }

  /// 서비스 초기화 (앱 시작 시 호출)
  Future<Either<Failure, bool>> initialize() async {
    if (_isInitialized && !_isCacheExpired) {
      DebugLogger.log('Lookups 서비스가 이미 초기화되어 있습니다', tag: 'LOOKUPS');
      return const Right(true);
    }

    if (_isLoading) {
      DebugLogger.log('Lookups 초기화가 이미 진행 중입니다', tag: 'LOOKUPS');
      return const Left(ServerFailure(message: '초기화가 이미 진행 중입니다'));
    }

    _isLoading = true;
    DebugLogger.log('Lookups 서비스 초기화 시작', tag: 'LOOKUPS');

    try {
      final result = await _dataSource.getAllLookups();
      
      return result.fold(
        (failure) {
          _isLoading = false;
          _isInitialized = false;
          _initializationController.add(false);
          DebugLogger.logError('Lookups 초기화 실패', error: failure.message);
          return Left(failure);
        },
        (data) {
          _cachedData = data;
          _lastUpdated = DateTime.now();
          _isInitialized = true;
          _isLoading = false;
          _initializationController.add(true);
          
          DebugLogger.log('Lookups 서비스 초기화 완료', tag: 'LOOKUPS', data: {
            'manufacturers': data.manufacturers.length,
            'equipment_names': data.equipmentNames.length,
            'equipment_categories': data.equipmentCategories.length,
            'equipment_statuses': data.equipmentStatuses.length,
          });
          
          return const Right(true);
        },
      );
    } catch (e) {
      _isLoading = false;
      _isInitialized = false;
      _initializationController.add(false);
      DebugLogger.logError('Lookups 초기화 예외', error: e);
      return Left(ServerFailure(message: 'Lookups 초기화 중 예외 발생: $e'));
    }
  }

  /// 캐시 새로고침
  Future<Either<Failure, bool>> refresh() async {
    _isInitialized = false;
    _cachedData = null;
    _lastUpdated = null;
    return await initialize();
  }

  /// 전체 Lookups 데이터 조회
  Either<Failure, LookupData> getAllLookups() {
    if (!_isInitialized || _cachedData == null) {
      return const Left(ServerFailure(message: 'Lookups 서비스가 초기화되지 않았습니다'));
    }
    
    if (_isCacheExpired) {
      // 백그라운드에서 캐시 갱신
      unawaited(refresh());
      DebugLogger.log('Lookups 캐시가 만료되어 백그라운드 갱신을 시작합니다', tag: 'LOOKUPS');
    }
    
    return Right(_cachedData!);
  }

  /// 제조사 목록 조회
  Either<Failure, List<LookupItem>> getManufacturers() {
    return getAllLookups().fold(
      (failure) => Left(failure),
      (data) => Right(data.manufacturers),
    );
  }

  /// 장비명 목록 조회
  Either<Failure, List<EquipmentNameItem>> getEquipmentNames() {
    return getAllLookups().fold(
      (failure) => Left(failure),
      (data) => Right(data.equipmentNames),
    );
  }

  /// 장비 카테고리 조합 목록 조회
  Either<Failure, List<CategoryCombinationItem>> getEquipmentCategories() {
    return getAllLookups().fold(
      (failure) => Left(failure),
      (data) => Right(data.equipmentCategories),
    );
  }

  /// 회사 목록 조회
  Either<Failure, List<LookupItem>> getCompanies() {
    return getAllLookups().fold(
      (failure) => Left(failure),
      (data) => Right(data.companies),
    );
  }

  /// 창고 목록 조회
  Either<Failure, List<LookupItem>> getWarehouses() {
    return getAllLookups().fold(
      (failure) => Left(failure),
      (data) => Right(data.warehouses),
    );
  }

  /// 장비 상태 목록 조회
  Either<Failure, List<StatusItem>> getEquipmentStatuses() {
    return getAllLookups().fold(
      (failure) => Left(failure),
      (data) => Right(data.equipmentStatuses),
    );
  }

  /// 특정 제조사 정보 조회
  Either<Failure, LookupItem?> getManufacturerById(int id) {
    return getManufacturers().fold(
      (failure) => Left(failure),
      (manufacturers) {
        try {
          final manufacturer = manufacturers.firstWhere((item) => item.id == id);
          return Right(manufacturer);
        } catch (e) {
          return const Right(null);
        }
      },
    );
  }

  /// 특정 장비 상태 정보 조회
  Either<Failure, StatusItem?> getEquipmentStatusById(String id) {
    return getEquipmentStatuses().fold(
      (failure) => Left(failure),
      (statuses) {
        try {
          final status = statuses.firstWhere((item) => item.id == id);
          return Right(status);
        } catch (e) {
          return const Right(null);
        }
      },
    );
  }

  /// Equipment 폼용 매번 API 호출 메서드 (캐싱 없이)
  Future<Either<Failure, LookupData>> getLookupDataForEquipmentForm() async {
    DebugLogger.log('Equipment 폼용 Lookups 데이터 API 호출', tag: 'LOOKUPS');
    return await _dataSource.getAllLookups();
  }

  /// 대분류 목록 추출 (Equipment 폼용)
  Future<Either<Failure, List<String>>> getCategory1List() async {
    final result = await getLookupDataForEquipmentForm();
    return result.fold(
      (failure) => Left(failure),
      (data) {
        final category1List = data.equipmentCategories
            .map((item) => item.category1)
            .toSet()
            .toList()
            ..sort();
        return Right(category1List);
      },
    );
  }

  /// 중분류 목록 추출 (Equipment 폼용)
  Future<Either<Failure, List<String>>> getCategory2List(String category1) async {
    final result = await getLookupDataForEquipmentForm();
    return result.fold(
      (failure) => Left(failure),
      (data) {
        final category2List = data.equipmentCategories
            .where((item) => item.category1 == category1)
            .map((item) => item.category2)
            .toSet()
            .toList()
            ..sort();
        return Right(category2List);
      },
    );
  }

  /// 소분류 목록 추출 (Equipment 폼용)
  Future<Either<Failure, List<String>>> getCategory3List(String category1, String category2) async {
    final result = await getLookupDataForEquipmentForm();
    return result.fold(
      (failure) => Left(failure),
      (data) {
        final category3List = data.equipmentCategories
            .where((item) => item.category1 == category1 && item.category2 == category2)
            .map((item) => item.category3)
            .toSet()
            .toList()
            ..sort();
        return Right(category3List);
      },
    );
  }

  /// 캐시 통계 정보
  Map<String, dynamic> getCacheStats() {
    return {
      'initialized': _isInitialized,
      'loading': _isLoading,
      'last_updated': _lastUpdated?.toIso8601String(),
      'cache_expired': _isCacheExpired,
      'data_available': _cachedData != null,
      'manufacturers_count': _cachedData?.manufacturers.length ?? 0,
      'equipment_names_count': _cachedData?.equipmentNames.length ?? 0,
      'equipment_categories_count': _cachedData?.equipmentCategories.length ?? 0,
      'equipment_statuses_count': _cachedData?.equipmentStatuses.length ?? 0,
      'companies_count': _cachedData?.companies.length ?? 0,
      'warehouses_count': _cachedData?.warehouses.length ?? 0,
    };
  }

  /// 메모리 정리
  void dispose() {
    _initializationController.close();
    _cachedData = null;
    _lastUpdated = null;
    _isInitialized = false;
    _isLoading = false;
  }
}

/// LookupsService 편의 확장 메서드
extension LookupsServiceExtensions on LookupsService {
  /// 드롭다운용 제조사 리스트 (id, name 맵)
  Either<Failure, Map<int, String>> getManufacturerDropdownItems() {
    return getManufacturers().fold(
      (failure) => Left(failure),
      (manufacturers) {
        final Map<int, String> items = {};
        for (int i = 0; i < manufacturers.length; i++) {
          final manufacturer = manufacturers[i];
          final id = manufacturer.id ?? (i + 1); // id가 null이면 인덱스 기반 ID 사용
          items[id] = manufacturer.name;
        }
        return Right(items);
      },
    );
  }

  /// 드롭다운용 장비 상태 리스트 (id, name 맵)
  Either<Failure, Map<String, String>> getEquipmentStatusDropdownItems() {
    return getEquipmentStatuses().fold(
      (failure) => Left(failure),
      (statuses) {
        final Map<String, String> items = {};
        for (final status in statuses) {
          items[status.id] = status.name;
        }
        return Right(items);
      },
    );
  }

  /// Equipment 폼용 드롭다운 리스트 생성 (매번 API 호출)
  Future<Either<Failure, Map<String, dynamic>>> getEquipmentFormDropdownData() async {
    final result = await getLookupDataForEquipmentForm();
    return result.fold(
      (failure) => Left(failure),
      (data) {
        // 제조사 리스트 (드롭다운 + 직접입력용)
        final List<String> manufacturers = data.manufacturers.map((item) => item.name).toList();
        
        // 장비명 리스트 (드롭다운 + 직접입력용)
        final List<String> equipmentNames = data.equipmentNames.map((item) => item.name).toList();
        
        // 회사 리스트 (드롭다운 전용)
        final Map<int, String> companies = {};
        for (final company in data.companies) {
          if (company.id != null) {
            companies[company.id!] = company.name;
          }
        }
        
        // 창고 리스트 (드롭다운 전용)
        final Map<int, String> warehouses = {};
        for (final warehouse in data.warehouses) {
          if (warehouse.id != null) {
            warehouses[warehouse.id!] = warehouse.name;
          }
        }
        
        // 대분류 리스트 (드롭다운 + 직접입력용)
        final List<String> category1List = data.equipmentCategories
            .map((item) => item.category1)
            .toSet()
            .toList()
            ..sort();
            
        return Right({
          'manufacturers': manufacturers,
          'equipment_names': equipmentNames,
          'companies': companies,
          'warehouses': warehouses,
          'category1_list': category1List,
          'category_combinations': data.equipmentCategories,
        });
      },
    );
  }
}