/**
 * How long ago something happened, in a few words: "just now", "5 min
 * ago", "3 h ago", "yesterday", "4 days ago".
 *
 * @param {string} iso - When, as an ISO date.
 * @param {number} now - The time to count from.
 * @returns {string} Empty for a date that does not read.
 */
export const timeAgo = (iso: string, now: number = Date.now()): string => {
  const minutes = Math.floor((now - new Date(iso).getTime()) / 60000);
  if (Number.isNaN(minutes)) {
    return '';
  }
  if (minutes < 1) {
    return 'just now';
  }
  if (minutes < 60) {
    return `${minutes} min ago`;
  }
  const hours = Math.floor(minutes / 60);
  if (hours < 24) {
    return `${hours} h ago`;
  }
  const days = Math.floor(hours / 24);
  return days === 1 ? 'yesterday' : `${days} days ago`;
};