// Absences are calendar dates stored as UTC dates, independent of the server timezone.
export function absenceDate(value: string) {
  if (!/^\d{4}-\d{2}-\d{2}$/.test(value)) throw new Error("Ungültiges Datum.");
  const date = new Date(`${value}T00:00:00.000Z`);
  if (Number.isNaN(date.getTime()) || date.toISOString().slice(0, 10) !== value)
    throw new Error("Ungültiges Datum.");
  return date;
}

export function isAbsenceDate(value: string) {
  try {
    absenceDate(value);
    return true;
  } catch {
    return false;
  }
}

export function absenceToday(now = new Date()) {
  const parts = new Intl.DateTimeFormat("en-CA", {
    timeZone: "Europe/Berlin",
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
  }).formatToParts(now);
  const part = (type: string) =>
    parts.find((item) => item.type === type)!.value;
  return `${part("year")}-${part("month")}-${part("day")}`;
}

export function canManageKitaAbsences(role: string) {
  return ["ADMIN", "KOORDINATOR", "ERZIEHER"].includes(role);
}

export function canEditOwnAbsence(startDate: string, today: string) {
  return startDate > today;
}