export function DateParse(date: string | Date, startDate: Date = new Date()) {
  const diffMs = startDate.getTime() - new Date(date).getTime();
  const diffSec = Math.abs(Math.floor(diffMs / 1000));
  const diffMin = Math.abs(Math.floor(diffSec / 60));
  const diffHour = Math.abs(Math.floor(diffMin / 60));
  const diffDay = Math.abs(Math.floor(diffHour / 24));
  const diffMonth = Math.abs(Math.floor(diffDay / 30));
  const diffYear = Math.abs(Math.floor(diffMonth / 12));
  
  const diffStr = diffMs < 0
    ? "後"
    : "前";
  
  switch (true) {
    case diffSec < 60:
      return `${diffSec}秒${diffStr}`;
    case diffMin < 60:
      return `${diffMin}分${diffStr}`;
    case diffHour < 24:
      return `${diffHour}時間${diffStr}`;
    case diffDay < 30:
      return `${diffDay}日${diffStr}`;
    case diffMonth < 12:
      return `${diffMonth}ヶ月${diffStr}`;
    default:
      return `${diffYear}年${diffStr}`;
  }
}