import { Queue, type ConnectionOptions, type QueueOptions } from 'bullmq';
import type { Config } from './config.js';
import type { Channel, SendJob } from './types.js';

export const QUEUE_NAMES: Record<Channel, string> = {
  fcm: 'tcef-fcm',
  email: 'tcef-email',
};

/**
 * BullMQ connection options. We hand BullMQ plain options (not a shared ioredis
 * instance) so it manages its own blocking/non-blocking connections and sets
 * maxRetriesPerRequest:null on workers itself.
 */
export function redisConnection(cfg: Config): ConnectionOptions {
  return {
    host: cfg.redis.host,
    port: cfg.redis.port,
    password: cfg.redis.password,
    db: cfg.redis.db,
  };
}

export function createQueues(cfg: Config): Record<Channel, Queue<SendJob>> {
  const opts: QueueOptions = {
    connection: redisConnection(cfg),
    defaultJobOptions: {
      attempts: cfg.retries.attempts,
      backoff: { type: 'exponential', delay: cfg.retries.backoffMs },
      removeOnComplete: { count: 1000 },
      removeOnFail: false, // keep failures = dead-letter for inspection
    },
  };
  return {
    fcm: new Queue<SendJob>(QUEUE_NAMES.fcm, opts),
    email: new Queue<SendJob>(QUEUE_NAMES.email, opts),
  };
}

/**
 * Job id = `${channel}_${notificationId}` so BullMQ itself dedupes enqueues:
 * re-polling the same pending doc will not create a second job.
 * (BullMQ rejects custom job ids containing ':', hence the underscore.)
 */
export function jobId(job: SendJob): string {
  return `${job.channel}_${job.notificationId}`;
}