export type RateLimiter = {
  check: (ip: string) => boolean;
};

export function createRateLimiter(
  limit: number,
  windowMs: number,
  now: () => number = () => Date.now(),
): RateLimiter {
  const hits = new Map<string, number[]>();

  return {
    check(ip: string) {
      const t = now();
      const recent = (hits.get(ip) ?? []).filter((ts) => t - ts < windowMs);
      if (recent.length >= limit) {
        hits.set(ip, recent);
        return false;
      }
      recent.push(t);
      hits.set(ip, recent);
      return true;
    },
  };
}