import { Injectable, Logger } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Subscription } from './entities/subscription.entity';
import { Brackets, Repository } from 'typeorm';
import { MailService } from 'src/mail/mail.service';
import { Cron, CronExpression } from '@nestjs/schedule';
import * as dayjs from 'dayjs';
import {
  getBenefits,
  getPurchaseUrl,
  getSubsctriptionName,
} from './helpers/subscription.helper';

@Injectable()
export class SubscriptionsEmailService {
  constructor(
    @InjectRepository(Subscription)
    private readonly _subscriptionsRepository: Repository<Subscription>,
    private readonly _mailService: MailService,
  ) {}

  @Cron(CronExpression.EVERY_DAY_AT_11AM)
  async handleExpiringReminderCron() {
    Logger.log('Looking for subscriptions expiring soon...');
    const now = dayjs();
    const in24Hours = now.add(24, 'hour').toDate();
    const last24Hours = now.subtract(24, 'hour').toDate();

    // Query for subscriptions expiring in the next 24 hours
    // and that haven't had a reminder sent in the last 24 hours
    const expiring = await this._subscriptionsRepository
      .createQueryBuilder('subscription')
      // using withDeleted to include soft-deleted users data then exclude them later
      // otherwise, the query would not join the user table correctly
      .withDeleted()
      .leftJoinAndSelect('subscription.user', 'user')
      .where('subscription.periodEnd BETWEEN :now AND :in24Hours', {
        now,
        in24Hours,
      })
      .andWhere('subscription.status = :status', { status: 'cancelled' })
      .andWhere(
        new Brackets((qb) => {
          qb.where('subscription.expirationReminderSentAt IS NULL').orWhere(
            'subscription.expirationReminderSentAt < :last24Hours',
            { last24Hours },
          );
        }),
      )
      .andWhere('user.deletedAt IS NULL')
      .getMany();

    if (expiring.length === 0) {
      Logger.log('No subscriptions expiring soon.');
      return;
    }

    // Sending reminder emails
    const renewSubscriptionTemplateId = 'd-681385c5f24c412e95ad70bc6410511d';
    const recipients = expiring.map((subscription) => ({
      email: subscription.user.email,
      data: {
        subscriptionAddonUrl: getPurchaseUrl(subscription.type),
        subscriptionName: getSubsctriptionName(subscription.type),
        benefits: getBenefits(subscription.type),
      },
    }));

    await this._mailService.sendBatch(renewSubscriptionTemplateId, recipients);

    // Setting the reminder sent date
    const ids = expiring.map((s) => s.id);
    await this._subscriptionsRepository
      .createQueryBuilder()
      .update()
      .set({ expirationReminderSentAt: new Date() })
      .whereInIds(ids)
      .execute();

    Logger.log(
      `Sent reminder emails for ${expiring.length} expiring subscriptions.`,
    );
  }
}