export function formatCountdown(seconds: number): string {
  if (seconds < 60) return `${seconds}秒`;
  return `${Math.floor(seconds / 60)}分${seconds % 60}秒`;
}

export function formatDateLabel(dateStr: string, now: Date = new Date()): string {
  const date = new Date(dateStr);
  if (Number.isNaN(date.getTime())) return "—";

  const today = new Date(now.getFullYear(), now.getMonth(), now.getDate());
  const yesterday = new Date(today.getTime() - 86_400_000);
  const dateDay = new Date(date.getFullYear(), date.getMonth(), date.getDate());

  if (dateDay.getTime() >= today.getTime()) return "今天";
  if (dateDay.getTime() >= yesterday.getTime()) return "昨天";

  const year = date.getFullYear();
  const month = String(date.getMonth() + 1).padStart(2, "0");
  const day = String(date.getDate()).padStart(2, "0");
  return `${year}-${month}-${day}`;
}

export function formatDurationUnit(ms: null | number): { suffix: string; value: number } {
  if (ms === null) return { suffix: "", value: 0 };
  if (ms < 60000) return { suffix: "秒", value: roundToOne(ms / 1000) };
  if (ms < 3600000) return { suffix: "分钟", value: roundToOne(ms / 60000) };
  return { suffix: "小时", value: roundToOne(ms / 3600000) };
}

export function formatRelativeTime(timestamp: null | string, now = new Date()): string {
  if (!timestamp) return "尚无检查数据";

  const time = new Date(timestamp).getTime();
  if (Number.isNaN(time)) return "尚无检查数据";

  const diffSeconds = Math.max(0, Math.floor((now.getTime() - time) / 1000));
  if (diffSeconds < 60) return `${diffSeconds}秒前`;

  const diffMinutes = Math.floor(diffSeconds / 60);
  if (diffMinutes < 60) return `${diffMinutes}分钟前`;

  const diffHours = Math.floor(diffMinutes / 60);
  if (diffHours < 24) return `${diffHours}小时前`;

  return `${Math.floor(diffHours / 24)}天前`;
}

export function isOlderThan(timestamp: null | string, ageMs: number, now = new Date()): boolean {
  if (!timestamp) return false;
  const time = new Date(timestamp).getTime();
  if (Number.isNaN(time)) return false;
  return now.getTime() - time > ageMs;
}

export function subtractHours(date: Date, hours: number): Date {
  const result = new Date(date);
  result.setTime(result.getTime() - hours * 60 * 60 * 1000);
  return result;
}

function roundToOne(value: number): number {
  return Math.round(value * 10) / 10;
}