export class FixedWindowRateLimiter {

  private readonly buckets = new Map<string, { startedAt: number; count: number }>();

  consume(key: string, limit: number, windowMs: number, now = Date.now()) {

    const current = this.buckets.get(key);

    if (!current || now - current.startedAt >= windowMs) {

      this.buckets.set(key, { startedAt: now, count: 1 });

      return { allowed: true, remaining: Math.max(0, limit - 1), retryAfterSeconds: 0 };

    }

    current.count += 1;

    const retryAfterSeconds = Math.max(1, Math.ceil((windowMs - (now - current.startedAt)) / 1000));

    return {

      allowed: current.count <= limit,

      remaining: Math.max(0, limit - current.count),

      retryAfterSeconds,

    };

  }

}