type Bucket = {
  count: number;
  resetAt: number;
};

const buckets = new Map<string, Bucket>();

export function checkRateLimit(key: string, limit = 5, windowMs = 15 * 60 * 1000) {
  const now = Date.now();
  const bucket = buckets.get(key);

  if (!bucket || bucket.resetAt <= now) {
    buckets.set(key, { count: 1, resetAt: now + windowMs });
    return { allowed: true, remaining: limit - 1 };
  }

  if (bucket.count >= limit) {
    return { allowed: false, remaining: 0 };
  }

  bucket.count += 1;
  return { allowed: true, remaining: limit - bucket.count };
}