---

export type DisplayTextValue = number | string | BusinessDay | null | undefined;

function isBusinessDay(value: unknown): value is BusinessDay {
  return (
    typeof value === 'object' &&
    value !== null &&
    'year' in value &&
    'month' in value &&
    'day' in value
  );
}

export function formatDisplayText(value: DisplayTextValue): string {
  if (value === null || value === undefined) {
    return '';
  }

  if (typeof value === 'string' || typeof value === 'number') {
    return String(value);
  }

  if (isBusinessDay(value)) {
    const day = String(value.day).padStart(2, '0');
    const month = String(value.month).padStart(2, '0');

    return `${day}.${month}.${value.year}`;
  }

  return '';
}