/** Возвращает функции для конвертации дат: toUnix ("yyyy-MM-dd" → timestamp) и fromUnix (timestamp → "yyyy-MM-dd"). */
export const convertDateToTimestamp = () => {
  const toUnix = (dateStr: string): number | null => {
    const [year, month, day] = dateStr.split('-').map(Number);
    if (!day || !month || !year) {
      return null;
    }

    const date = new Date(Date.UTC(year, month - 1, day));
    if (isNaN(date.getTime())) {
      return null;
    }

    return Math.floor(date.getTime() / 1000);
  };

  const fromUnix = (timestamp: number): string => {
    const date = new Date(timestamp * 1000);

    const yyyy = date.getUTCFullYear();
    const mm = String(date.getUTCMonth() + 1).padStart(2, '0');
    const dd = String(date.getUTCDate()).padStart(2, '0');

    return `${yyyy}-${mm}-${dd}`;
  };

  return {
    toUnix,
    fromUnix,
  };
};