interface Bucket {
  count: number;
  resetAt: number;
}

export class RateLimiter {
  private buckets = new Map<string, Bucket>();

  constructor(
    private readonly max: number,
    private readonly windowMs: number,
  ) {}

  check(ip: string): boolean {
    const now = Date.now();
    if (this.buckets.size > 10_000) this.prune(now);
    const existing = this.buckets.get(ip);
    const bucket = existing && existing.resetAt > now ? existing : { count: 0, resetAt: now + this.windowMs };
    if (!existing || bucket !== existing) this.buckets.set(ip, bucket);
    bucket.count++;
    return bucket.count <= this.max;
  }

  private prune(now: number): void {
    for (const [ip, bucket] of this.buckets) {
      if (bucket.resetAt <= now) this.buckets.delete(ip);
    }
  }
}