let nextId = 0;

const TIMERS = {};

export default class Timer {
  id: number;

  onCancel: Function;

  constructor() {
    this.id = null;
  }

  clear() {
    if (this.id) {
      if (this.onCancel) {
        this.onCancel(this);
      }
      clearTimeout(TIMERS[this.id]);
      delete TIMERS[this.id];
      this.id = null;
    }
  }

  start(timeout, callback, cancel = null) {
    this.clear();

    this.id = ++nextId;
    this.onCancel = cancel;

    TIMERS[this.id] = setTimeout(() => {
      delete TIMERS[this.id];
      this.id = null;

      callback();
    }, timeout == null ? 1e8 : timeout);
  }

  isRunning() {
    return this.id != null;
  }
}