import { derived, readable, type Readable } from 'svelte/store';

export const time = readable(new Date(), function start(set) {
  const interval = setInterval(() => {
    set(new Date());
  }, 10000); //Every 10sec is enough, we don't need that much granularity

  return function stop() {
    clearInterval(interval);
  };
});

export function secondsSince(date: Date): Readable<number> {
  return derived(time, ($time) => Math.round(($time.getTime() - date.getTime()) / 1000));
}

export function relativeTime(seconds: number): string | null {
  const min = 60;
  if (seconds < min) {
    return 'just now';
  }

  const hour = 60 * min;
  if (seconds < hour) {
    return `${Math.floor(seconds / min)}min`;
  }

  const day = hour * 24;
  if (seconds < day) {
    return `${Math.floor(seconds / hour)}h`;
  }
  const maxRelative = day * 31;
  if (seconds < maxRelative) {
    return `${Math.floor(seconds / day)}d`;
  }
  return null;
}