interface QueueElement {
  resolve: (value?: unknown) => void;
  reject: () => any;
}

class Mutex {
  queue: QueueElement[] = [];
  locked = false;

  async acquire() {
    if (!this.locked) {
      this.locked = true;
    } else {
      return new Promise((resolve, reject) => this.queue.push({ resolve, reject }));
    }
  }

  release() {
    if (this.queue.length) {
      const first = this.queue.shift();

      first!.resolve();
    } else {
      this.locked = false;
    }
  }
}

export default Mutex;