/**
 * throttle and debounce given function in regular time interval,
 * but with the difference that the last call will be debounced and therefore never missed.
 * @param {*} function to throttle and debounce
 * @param {*} time desired interval to execute function
 * @returns callback
 */
export const bounce = (
  fn: () => void,
  time: number,
) => {
  let throttle: number | undefined;
  let debounce: number | undefined;
  return (/*...args*/) => {
    if (throttle) {
    	clearTimeout(debounce);
    	debounce = setTimeout(() => fn(/*...args*/), time);
      return;
    }
    fn(/*...args*/);
    throttle = setTimeout(() => {
      clearTimeout(throttle);
    }, time);
  };
};

/**
 * Intl.DateTimeFormat object
 *
 * example:
 *
 *   console.log(dateTime.format(new Date()));
 */
export const dateTime = new Intl.DateTimeFormat(navigator.language /* navigator.language */, {
  dateStyle: 'medium',
  timeStyle: 'short',
});

/**
 * format time relative to now, such as 5min ago
 *
 * @param {Date} time
 * @param {string} locale
 * @returns string
 *
 * example:
 *
 *   console.log(timeAgo(new Date(Date.now() - 10000)));
 *
 */
const timeAgo = (
  time: Date,
  locale: string = 'en',
) => {
  const relativeTime = new Intl.RelativeTimeFormat(locale, {
    numeric: 'auto',
    style: 'long',
  });
  const timeSince = (Date.now() - time.getTime()) * 0.001;
  const minutes = Math.floor(timeSince / 60);
  const hours = Math.floor(minutes / 60);
  const days = Math.floor(hours / 24);
  const months = Math.floor(days / 30);
  const years = Math.floor(months / 12);

  if (years > 0) {
    return relativeTime.format(0 - years, 'year');
  } else if (months > 0) {
    return relativeTime.format(0 - months, 'month');
  } else if (days > 0) {
    return relativeTime.format(0 - days, 'day');
  } else if (hours > 0) {
    return relativeTime.format(0 - hours, 'hour');
  } else if (minutes > 0) {
    return relativeTime.format(0 - minutes, 'minute');
  } else {
    return relativeTime.format(Math.round(0 - timeSince), 'second');
  }
};

/**
 * formatTime shows relative time if it is less than 24h else absolute datetime
 *
 * @param {time} date object to format
 * @return string
 */
export const formatTime = (time: Date) => {
  const yesterday = new Date(Date.now() - (24 * 60 * 60 * 1000));
  if (time > yesterday) {
    return timeAgo(time);
  } else {
    return dateTime.format(time);
  };
};