mnemo_cards/mnemo_cards_backend/lib/discounts/discounts_manager.dart

import 'dart:developer';

import 'package:injectable/injectable.dart';
import 'package:mnemo_cards_backend/database/daos/discount_dao.dart';
import 'package:mnemo_cards_backend/database/daos/user_dao.dart';
import 'package:mnemo_cards_backend/database/database.dart';
import 'package:mnemo_cards_backend/discounts/discount_drift_extension.dart';
import 'package:mnemo_cards_common_backend/mnemo_cards_common_backend.dart';
import 'package:mnemo_cards_common/mnemo_cards_common.dart' hide DateTimeExt;
import 'package:mnemo_cards_common/src/utils/utils.dart';

@lazySingleton
class DiscountsManager {
  final AppDatabase _db;
  final DiscountDao _discountDao;
  final UserDao _userDao;

  DiscountsManager(this._db)
      : _discountDao = _db.discountDao,
        _userDao = _db.userDao;

  Future<void> applyDiscount({
    required Iterable<DiscountModel> discounts,
    required UserModel user,
  }) async {
    if (user.id == null) return;
    
    // Получаем ID скидок
    final discountIds = discounts
        .where((d) => d.id != null)
        .map((d) => d.id!)
        .toList();
    
    if (discountIds.isEmpty) return;
    
    // Добавляем скидки пользователю через junction таблицу
    await _discountDao.grantDiscountsToUser(user.id!, discountIds);
  }

  Future<void> changeCampaignStatus(DiscountCampaign campaign) async {
    final now = DateTime.now();
    String? targetStatus;
    
    if (campaign.status == 'created' &&
        now.isBetween(campaign.start, campaign.finish)) {
      targetStatus = 'active';
    } else if (campaign.status == 'active') {
      if (now.isBefore(campaign.start)) {
        targetStatus = 'created';
      } else if (now.isAfter(campaign.finish)) {
        targetStatus = 'expired';
      }
    }
    
    if (targetStatus != null && targetStatus != campaign.status) {
      await _discountDao.updateCampaignStatus(campaign.id, targetStatus);
    }
  }

  Future<DiscountError?> applyCampaign(DiscountCampaign campaign) async {
    final now = DateTime.now();
    if (!now.isBetween(campaign.start, campaign.finish)) {
      if (now.isBefore(campaign.start)) {
        return DiscountError(DiscountErrorType.notStarted);
      }
      return DiscountError(DiscountErrorType.expired);
    }
    // TODO: Implement applying campaign to users based on tags
    // This would require querying UserDatas with matching tags
    return null;
  }

  Future<void> removeDiscount({
    required DiscountCampaign campaign,
    required UserModel user,
  }) async {
    if (user.id == null) return;
    
    // Получаем скидки кампании
    final discounts = await _discountDao.getDiscountsByCampaignId(campaign.id);
    final discountIds = discounts.map((d) => d.id).toList();
    
    if (discountIds.isEmpty) return;
    
    // Удаляем скидки пользователя
    await _discountDao.revokeDiscountsFromUser(user.id!, discountIds);
  }

  Future<double> getProductDiscount(
    MnemoCardsProductModel model,
    UserData userData,
  ) async {
    double maxDiscount = 0;
    
    // Получаем активные скидки пользователя из junction таблицы
    final userDiscounts = await _discountDao.getUserDiscounts(userData.userId);
    for (final discount in userDiscounts) {
      final discountDto = discount.toDto();
      if (discountDto.discountPercent > maxDiscount &&
          discountDto.products.any((p) => model.equalsDto(p))) {
        maxDiscount = discountDto.discountPercent;
      }
    }

    // Получаем активные кампании
    final user = await _userDao.getUserById(userData.userId);
    if (user == null) return maxDiscount;
    
    final userDataModel = await _userDao.getUserData(userData.userId);
    final userTags = userDataModel?.tags ?? [];
    
    final activeCampaigns = await _discountDao.getActiveCampaignsForUser(
      userTags: userTags,
      productType: model.type.name,
      productId: model.id.toString(),
    );
    
    for (final campaign in activeCampaigns) {
      final discounts = await _discountDao.getDiscountsByCampaignId(campaign.id);
      for (final discount in discounts) {
        final discountDto = discount.toDto();
        if (discountDto.discountPercent > maxDiscount &&
            discountDto.products.any((p) => model.equalsDto(p))) {
          maxDiscount = discountDto.discountPercent;
        }
      }
    }
    
    return maxDiscount;
  }

  Future<List<DiscountCampaign>> discountCampaignsForUser(
    UserData userData, {
    MnemoCardsProductModel? product,
  }) async {
    final userTags = userData.tags;
    return await _discountDao.getActiveCampaignsForUser(
      userTags: userTags,
      productType: product?.type.name,
      productId: product?.id.toString(),
    );
  }

  Future<List<DiscountCampaignDto>> discountCampaigns() async {
    final campaigns = await _discountDao.getAllCampaigns();
    final dtos = await Future.wait(
      campaigns.map((c) async => await c.toDto(_discountDao)),
    );
    return dtos;
  }

  Future<String?> deleteDiscountCampaign(String id) async {
    try {
      final campaign = await _discountDao.getCampaignById(id);
      if (campaign == null) {
        return 'Campaign $id not found';
      }
      if (campaign.status != 'disabled') {
        return 'Disable campaign before deleting';
      }
      await _discountDao.deleteCampaign(id);
      return null;
    } catch (e, s) {
      log('Error when deleting discount campaign', error: e, stackTrace: s);
      return 'Error $e';
    }
  }

  Future<bool> addDiscount(DiscountCampaignDto dto) async {
    try {
      return await _db.transaction(() async {
        // Создаем кампанию
        final campaignCompanion = dto.toCompanion();
        final campaignId = await _discountDao.createCampaign(campaignCompanion);
        
        // Создаем скидки
        final discountCompanions = dto.discounts
            .map((discountDto) => discountDto.toCompanion(campaignId))
            .toList();
        
        for (final discountCompanion in discountCompanions) {
          await _discountDao.createDiscount(discountCompanion);
        }

        return true;
      });
    } catch (e, s) {
      print('error when adding campaign');
      log('error when adding campaign', error: e, stackTrace: s);
      return false;
    }
  }
}

class DiscountError {
  final String? message;
  final DiscountErrorType type;

  DiscountError(this.type, {this.message});
}

enum DiscountErrorType {
  notAvailable,
  notStarted,
  expired,
}