function pad2(v: number): string {
  return String(v).padStart(2, "0");
}

/**
 * 按本地时区格式化日期（仅日期部分）。
 * 支持 token：YYYY、YY、MM、M、DD、D
 */
export function formatLocalDate(ms: number, format: string = "YYYY-MM-DD HH:mm:ss"): string {
  const d = new Date(ms);
  if (Number.isNaN(d.getTime())) return "";

  const year = d.getFullYear();
  const month = d.getMonth() + 1;
  const day = d.getDate();
  const hour = d.getHours();
  const minute = d.getMinutes();
  const second = d.getSeconds();
  const tokenMap: Record<string, string> = {
    YYYY: String(year),
    YY: String(year).slice(-2),
    MM: pad2(month),
    M: String(month),
    DD: pad2(day),
    D: String(day),
    HH: pad2(hour),
    H: String(hour),
    mm: pad2(minute),
    m: String(minute),
    ss: pad2(second),
    s: String(second),
  };

  return format.replace(/YYYY|YY|MM|M|DD|D|HH|H|mm|m|ss|s/g, (token) => tokenMap[token] ?? token);
}