headplane/app/utils/time.ts

const UNITS: [Intl.RelativeTimeFormatUnit, number][] = [
  ["year", 365 * 24 * 60 * 60],
  ["month", 30 * 24 * 60 * 60],
  ["day", 24 * 60 * 60],
  ["hour", 60 * 60],
  ["minute", 60],
];

const relative = new Intl.RelativeTimeFormat("en", { numeric: "auto" });

/**
 * Formats the time since a date in its largest unit, e.g. "3 hours ago".
 */
export function formatTimeDelta(date: Date): string {
  const seconds = Math.round((Date.now() - date.getTime()) / 1000);
  for (const [unit, size] of UNITS) {
    if (seconds >= size) {
      return relative.format(-Math.floor(seconds / size), unit);
    }
  }

  return "just now";
}

/**
 * Formats the time until a date in its largest unit, e.g. "in 4 days".
 */
export function formatTimeUntil(date: Date): string {
  const seconds = Math.round((date.getTime() - Date.now()) / 1000);
  for (const [unit, size] of UNITS) {
    if (seconds >= size) {
      return relative.format(Math.floor(seconds / size), unit);
    }
  }

  return "now";
}