/**
 * 统一日期工具函数 — 替代分散在各页面的内联日期格式化
 */

/** 格式化为 YYYY-MM-DD */
export function formatDate(iso: string | null | undefined): string {
  if (!iso) return '-';
  const d = new Date(iso);
  if (isNaN(d.getTime())) return '-';
  const y = d.getFullYear();
  const m = String(d.getMonth() + 1).padStart(2, '0');
  const day = String(d.getDate()).padStart(2, '0');
  return `${y}-${m}-${day}`;
}

/** 格式化为 YYYY-MM-DD HH:mm */
export function formatDateTime(iso: string | null | undefined): string {
  if (!iso) return '-';
  const d = new Date(iso);
  if (isNaN(d.getTime())) return '-';
  const date = formatDate(iso);
  const h = String(d.getHours()).padStart(2, '0');
  const min = String(d.getMinutes()).padStart(2, '0');
  return `${date} ${h}:${min}`;
}

/** 格式化为 YYYY-MM-DD HH:mm:ss */
export function formatDateTimeFull(iso: string | null | undefined): string {
  if (!iso) return '-';
  const d = new Date(iso);
  if (isNaN(d.getTime())) return '-';
  const base = formatDateTime(iso);
  const s = String(d.getSeconds()).padStart(2, '0');
  return `${base}:${s}`;
}

/** 获取今天的 YYYY-MM-DD */
export function today(): string {
  const d = new Date();
  const y = d.getFullYear();
  const m = String(d.getMonth() + 1).padStart(2, '0');
  const day = String(d.getDate()).padStart(2, '0');
  return `${y}-${m}-${day}`;
}

/** 相对时间：今天/昨天/前天/更早 */
export function toRelativeDate(iso: string | null | undefined): string {
  if (!iso) return '-';
  const d = new Date(iso);
  if (isNaN(d.getTime())) return '-';

  const now = new Date();
  const todayStart = new Date(now.getFullYear(), now.getMonth(), now.getDate());
  const targetStart = new Date(d.getFullYear(), d.getMonth(), d.getDate());
  const diffDays = Math.round((todayStart.getTime() - targetStart.getTime()) / 86400000);

  if (diffDays === 0) return '今天';
  if (diffDays === 1) return '昨天';
  if (diffDays === 2) return '前天';
  return formatDate(iso);
}

/** 格式化为中文月日 + 星期 */
export function formatMonthDayWeek(iso: string | null | undefined): string {
  if (!iso) return '';
  const d = new Date(iso);
  if (isNaN(d.getTime())) return '';

  const weekdays = ['日', '一', '二', '三', '四', '五', '六'];
  const m = d.getMonth() + 1;
  const day = d.getDate();
  const w = weekdays[d.getDay()];
  return `${m}月${day}日 周${w}`;
}