import Redis from 'ioredis';

import type { QueueAdapter, QueueConfig, TaskPayload } from '../types.js';

const DEFAULT_VALKEY_URL = 'redis://localhost:6380';

export function createBullMQAdapter(config: QueueConfig): QueueAdapter {
  if (config.type !== 'bullmq') {
    throw new Error(`Expected config type "bullmq", got "${config.type}"`);
  }

  const url = config.url ?? process.env['VALKEY_URL'] ?? DEFAULT_VALKEY_URL;
  const redis = new Redis(url, { maxRetriesPerRequest: 3 });

  return {
    name: 'bullmq',

    async enqueue(queueName: string, payload: TaskPayload): Promise<void> {
      await redis.lpush(queueName, JSON.stringify(payload));
    },

    async dequeue(queueName: string): Promise<TaskPayload | null> {
      const item = await redis.rpop(queueName);
      if (!item) return null;
      return JSON.parse(item) as TaskPayload;
    },

    async length(queueName: string): Promise<number> {
      return redis.llen(queueName);
    },

    async publish(channel: string, message: string): Promise<void> {
      await redis.publish(channel, message);
    },

    subscribe(channel: string, handler: (message: string) => void): () => void {
      const sub = redis.duplicate();
      sub.subscribe(channel).catch(() => {});
      sub.on('message', (_ch: string, msg: string) => handler(msg));
      return () => {
        sub.unsubscribe(channel).catch(() => {});
        sub.disconnect();
      };
    },

    async close(): Promise<void> {
      await redis.quit();
    },
  };
}