import { InjectQueue } from '@nestjs/bullmq';
import { Injectable, Logger } from '@nestjs/common';
import { Cron, CronExpression } from '@nestjs/schedule';
import { Queue } from 'bullmq';
import { env } from '../config/env';
import { MerchantsService } from '../merchants/merchants.service';
import { GenerationTrigger } from './generation.service';

export const GENERATION_QUEUE = 'keyword-generation';

export interface GenerationJob {
  merchantId: string;
  trigger: GenerationTrigger;
}

@Injectable()
export class GenerationQueue {
  private readonly logger = new Logger(GenerationQueue.name);

  constructor(
    @InjectQueue(GENERATION_QUEUE) private readonly queue: Queue<GenerationJob>,
    private readonly merchants: MerchantsService,
  ) {}

  async enqueue(merchantId: string, trigger: GenerationTrigger): Promise<string> {
    // 짧은 시간 내 같은 업체가 여러 번 발행돼도 한 번만 처리 (60초 dedupe 창)
    const job = await this.queue.add(
      'generate',
      { merchantId, trigger },
      {
        deduplication: { id: `${merchantId}-${trigger}`, ttl: 60_000 },
        removeOnComplete: 100,
        removeOnFail: 500,
        attempts: 3,
        backoff: { type: 'exponential', delay: 5_000 },
      },
    );
    return String(job.id);
  }

  /** 주기 리프레시: 매일 03:00, N일 지난 업체를 큐에 적재 */
  @Cron(CronExpression.EVERY_DAY_AT_3AM)
  async scheduleRefresh() {
    const stale = await this.merchants.findStale(env.generation.refreshIntervalDays, 200);
    for (const m of stale) {
      await this.enqueue(m.id, 'scheduled');
    }
    if (stale.length) this.logger.log(`scheduled refresh queued: ${stale.length} merchants`);
  }
}