import { moment } from '../../libs';
import { value } from '../value';

export type TimerUnit = 'msec' | 'ms' | 'sec' | 's';

export type ITimer = {
  startedAt: Date;
  reset: () => ITimer;
  elapsed: (unit?: TimerUnit) => number;
};

export function timer(start?: Date) {
  let startedAt = start || new Date();
  const api: ITimer = {
    startedAt,
    reset() {
      startedAt = new Date();
      return api;
    },
    elapsed(unit: TimerUnit = 'msec') {
      const duration = elapsed(startedAt);
      switch (unit) {
        case 'ms':
        case 'msec':
          return duration.asMilliseconds();
        case 's':
        case 'sec':
          return value.round(duration.asSeconds(), 1);

        default:
          throw new Error(`Unit '${unit}' not supported `);
      }
    },
  };
  return api;
}

/**
 * Retrieves the elapsed milliseconds from the given date.
 */
export function elapsed(from: Date) {
  return moment.duration(moment().diff(from));
}