HTTP/1.1 200 OK
X-RateLimit-Limit: 120
X-RateLimit-Remaining: 115
X-RateLimit-Reset: 1705233060

{
  "success": false,
  "error": {
    "code": "RATE_LIMIT_EXCEEDED",
    "message": "Too many requests. Please retry after 60 seconds.",
    "details": {
      "retryAfter": 60,
      "limit": 30,
      "remaining": 0,
      "resetAt": "2026-01-15T10:35:00Z"
    }
  }
}

async function makeRequest(url, options) {
  const response = await fetch(url, options);

  // Verificar headers
  const remaining = response.headers.get('X-RateLimit-Remaining');
  const resetAt = response.headers.get('X-RateLimit-Reset');

  if (remaining < 10) {
    console.warn(`Atenção: apenas ${remaining} requisições restantes`);
  }

  return response;
}

async function requestWithRetry(url, options, maxRetries = 3) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    const response = await fetch(url, options);

    if (response.status !== 429) {
      return response;
    }

    const data = await response.json();
    const retryAfter = data.error?.details?.retryAfter || 60;

    console.log(`Rate limit. Aguardando ${retryAfter}s...`);
    await sleep(retryAfter * 1000);
  }

  throw new Error('Rate limit exceeded after max retries');
}

function sleep(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

class MessageQueue {
  constructor(messagesPerMinute = 30) {
    this.queue = [];
    this.interval = (60 * 1000) / messagesPerMinute;
    this.processing = false;
  }

  add(message) {
    this.queue.push(message);
    this.process();
  }

  async process() {
    if (this.processing) return;
    this.processing = true;

    while (this.queue.length > 0) {
      const message = this.queue.shift();
      await this.sendMessage(message);
      await sleep(this.interval);
    }

    this.processing = false;
  }

  async sendMessage(message) {
    // Enviar via API
  }
}

// Uso
const queue = new MessageQueue(30); // 30 msgs/min
queue.add({ to: '5511999999999', text: 'Olá!' });

const instances = ['inst-1', 'inst-2', 'inst-3'];
let currentIndex = 0;

function getNextInstance() {
  const instance = instances[currentIndex];
  currentIndex = (currentIndex + 1) % instances.length;
  return instance;
}

async function sendMessage(to, text) {
  const instanceId = getNextInstance();
  return api.sendMessage({ instanceId, to, text });
}