import { SQSClient, SendMessageCommand, ReceiveMessageCommand, DeleteMessageCommand } from '@aws-sdk/client-sqs';

const sqs = new SQSClient({ region: 'us-east-1' });
const QUEUE_URL = 'https://sqs.us-east-1.amazonaws.com/123456789/order-queue';

// Producer
async function enqueueOrder(order: Order) {
  await sqs.send(new SendMessageCommand({
    QueueUrl: QUEUE_URL,
    MessageBody: JSON.stringify(order),
    MessageGroupId: order.customerId,  // FIFO queue — ordered per customer
    MessageDeduplicationId: order.orderId,  // Deduplication
    DelaySeconds: 0,
  }));
}

// Consumer
async function processMessages() {
  while (true) {
    const result = await sqs.send(new ReceiveMessageCommand({
      QueueUrl: QUEUE_URL,
      MaxNumberOfMessages: 10,
      WaitTimeSeconds: 20,  // Long polling — wait up to 20s for messages
      VisibilityTimeout: 300,  // 5 minutes to process before redelivery
    }));

    for (const message of result.Messages || []) {
      try {
        const order = JSON.parse(message.Body!);
        await processOrder(order);

        // Delete after successful processing
        await sqs.send(new DeleteMessageCommand({
          QueueUrl: QUEUE_URL,
          ReceiptHandle: message.ReceiptHandle!,
        }));
      } catch (error) {
        // Don't delete — SQS will redeliver after VisibilityTimeout
        console.error('Processing failed, message will be redelivered');
      }
    }
  }
}
Message Queues — Kafka, RabbitMQ, SQS

Message Queues — Kafka, RabbitMQ, SQS

Message Queues — Kafka, RabbitMQ, SQS
