HTTP/1.1 200 OK
X-RateLimit-Limit: 100
X-RateLimit-Remaining: 87
X-RateLimit-Reset: 1704067200
Content-Type: application/json

HTTP/1.1 429 Too Many Requests
X-RateLimit-Limit: 100
X-RateLimit-Remaining: 0
X-RateLimit-Reset: 1704067200
X-RateLimit-Retry-After: 3600
Content-Type: application/json

{
  "error": "Rate limit exceeded",
  "code": "RATE_LIMIT_EXCEEDED",
  "message": "You have exceeded the rate limit. Please try again in 3600 seconds.",
  "retryAfter": 3600,
  "limit": 100,
  "window": "1h"
}

async function fetchWithRetry(url: string, options: RequestInit, maxRetries = 3): Promise<Response> {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    const response = await fetch(url, options);
    
    if (response.status !== 429) {
      return response;
    }
    
    const retryAfter = response.headers.get('X-RateLimit-Retry-After');
    const delay = retryAfter ? parseInt(retryAfter) * 1000 : Math.pow(2, attempt) * 1000;
    
    console.log(`Rate limited. Retrying after ${delay}ms...`);
    await new Promise(resolve => setTimeout(resolve, delay));
  }
  
  throw new Error('Max retries exceeded');
}

class RateLimitMonitor {
  private limits: Map<string, { remaining: number; reset: number }> = new Map();
  
  updateFromHeaders(endpoint: string, headers: Headers) {
    const remaining = parseInt(headers.get('X-RateLimit-Remaining') || '0');
    const reset = parseInt(headers.get('X-RateLimit-Reset') || '0');
    
    this.limits.set(endpoint, { remaining, reset });
    
    if (remaining < 10) {
      console.warn(`Low rate limit for ${endpoint}: ${remaining} remaining`);
    }
  }
  
  shouldThrottle(endpoint: string): boolean {
    const limit = this.limits.get(endpoint);
    if (!limit) return false;
    
    return limit.remaining < 5 && Date.now() / 1000 < limit.reset;
  }
}