type TimerState = 'init' | 'start' | 'pause' | 'resume' | 'stop';

class Timer {
  duration: number = 0;
  state: TimerState = 'init';

  _startTime: number = 0;
  _time: number = 0;

  constructor() {}

  start() {
    this.state = 'start';
    this._startTime = Date.now();
    this._time = this._startTime;
  }

  pause() {
    if (this.state === 'stop' || this.state === 'pause') {
      return;
    }

    this.state = 'pause';
    this.duration += Date.now() - this._time;
  }

  resume() {
    if (this.state !== 'pause') {
      return;
    }

    this.state = 'resume';
    this._time = Date.now();
  }

  stop() {
    if (this.state === 'stop') {
      return;
    }

    if (this.state === 'pause') {
      this.state = 'stop';
      return;
    }

    this.state = 'stop';
    this.duration += Date.now() - this._time;
  }

  getDurationSeconds() {
    return Math.round(this.duration / 1000);
  }
}

export default Timer;