const MINUTE = 60_000;
const HOUR = 3_600_000;
const DAY = 86_400_000;

export function relativeTime(dateStr: string): string {
  const now = Date.now();
  const then = new Date(dateStr).getTime();
  const diff = now - then;

  if (diff < MINUTE) {
    return "just now";
  }
  if (diff < HOUR) {
    const mins = Math.floor(diff / MINUTE);
    return `${mins}m ago`;
  }
  if (diff < DAY) {
    const hours = Math.floor(diff / HOUR);
    return `${hours}h ago`;
  }
  if (diff < 7 * DAY) {
    const days = Math.floor(diff / DAY);
    return `${days}d ago`;
  }

  return new Intl.DateTimeFormat(undefined, {
    month: "short",
    day: "numeric",
  }).format(new Date(dateStr));
}

export function fullDate(dateStr: string): string {
  return new Date(dateStr).toLocaleString();
}

export function formatCountdown(expiresAt: string): string {
  const diff = new Date(expiresAt).getTime() - Date.now();

  if (diff <= 0) {
    return "Expired";
  }

  const hours = Math.floor(diff / HOUR);
  const mins = Math.floor((diff % HOUR) / MINUTE);

  if (hours > 0) {
    return `${hours}h ${mins}m remaining`;
  }
  return `${mins}m remaining`;
}