'use strict';

const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));

class PoliteGate {
  constructor({ minMs = 8000, maxMs = 15000 } = {}) {
    if (!Number.isFinite(minMs) || !Number.isFinite(maxMs) || minMs < 0 || maxMs < minMs) {
      throw new Error('Invalid delay range');
    }
    this.minMs = minMs;
    this.maxMs = maxMs;
    this.lastRequestAt = 0;
  }

  async wait() {
    if (!this.lastRequestAt) return;
    const target = this.minMs + Math.floor(Math.random() * (this.maxMs - this.minMs + 1));
    const remaining = target - (Date.now() - this.lastRequestAt);
    if (remaining > 0) await sleep(remaining);
  }

  mark() {
    this.lastRequestAt = Date.now();
  }
}

module.exports = { PoliteGate, sleep };