/** 发帖/回复时间统一为相对时间：刚刚 / N分钟前 / N小时前 / N天前 / N个月前 / N年前 */
export function formatRelative(dateStr: string): string {
  const t = new Date(dateStr).getTime();
  const diff = Date.now() - t;
  const min = 60_000,
    hour = 60 * min,
    day = 24 * hour;
  if (diff < min) return "刚刚";
  if (diff < hour) return `${Math.floor(diff / min)}分钟前`;
  if (diff < day) return `${Math.floor(diff / hour)}小时前`;
  if (diff < 30 * day) return `${Math.floor(diff / day)}天前`;
  if (diff < 365 * day) return `${Math.floor(diff / (30 * day))}个月前`;
  return `${Math.floor(diff / (365 * day))}年前`;
}