import { Transport, MicroserviceOptions, RmqOptions } from '@nestjs/microservices';
import * as amqp from 'amqplib';

export const getRabbitMQOptions = (queueName: string, url?: string, pluginId?: string): MicroserviceOptions => {
  const routingKeys: string[] = ['#'];
  if (pluginId) {
    routingKeys.push(`plugin.${pluginId}.*`);
  }
  return {
    transport: Transport.RMQ,
    options: {
      urls: [url || process.env.RABBITMQ_URL || 'amqp://localhost:5672'],
      queue: queueName,
      exchange: 'system_events',
      exchangeType: 'topic',
      routingKey: routingKeys,
      queueOptions: {
        durable: true,
      },
      persistent: true,
      noAck: true,
    } as RmqOptions['options'] & { routingKey: string[] },
  };
};

export const getRabbitMQClientOptions = (url?: string) => {
  return {
    transport: Transport.RMQ as const,
    options: {
      urls: [url || process.env.RABBITMQ_URL || 'amqp://localhost:5672'],
      queue: 'core_queue',
      exchange: 'system_events',
      exchangeType: 'topic',
      queueOptions: {
        durable: true,
      },
    },
  };
};

/**
 * Bind a queue to the system_events exchange with the given routing keys.
 * NestJS 10's ServerRMQ does not automatically bind queues to exchanges,
 * so this must be called after app.startAllMicroservices().
 * NestJS 11+ handles this automatically via the exchange/routingKey options.
 */
export async function setupQueueBindings(
  queueName: string,
  routingKeys: string[],
  url?: string,
): Promise<void> {
  const rmqUrl = url || process.env.RABBITMQ_URL || 'amqp://localhost:5672';
  const conn = await amqp.connect(rmqUrl);
  try {
    const channel = await conn.createChannel();
    await channel.assertExchange('system_events', 'topic', { durable: true });
    await channel.assertQueue(queueName, { durable: true });
    for (const key of routingKeys) {
      await channel.bindQueue(queueName, 'system_events', key);
    }
    await channel.close();
  } finally {
    await conn.close().catch(() => {});
  }
}