const PRESENT = 'н.в.';

export function formatPeriod(
  startYear: number,
  endYear: number | null,
): string {
  if (endYear === null) {
    return `${startYear} — ${PRESENT}`;
  }
  if (startYear === endYear) {
    return String(startYear);
  }
  return `${startYear}–${endYear}`;
}

export function formatOptionalPeriod(
  startYear: number | null,
  endYear: number | null,
): string | null {
  if (startYear === null) {
    return null;
  }
  return formatPeriod(startYear, endYear);
}