export function addDays(date: Date, days: number): Date {
  const copy = new Date(date);
  copy.setHours(0, 0, 0, 0);
  copy.setDate(copy.getDate() + days);
  return copy;
}

export function formatYmd(date: Date): string {
  return `${date.getFullYear()}${String(date.getMonth() + 1).padStart(2, "0")}${String(date.getDate()).padStart(2, "0")}`;
}

export function formatIsoDate(date: Date): string {
  return `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, "0")}-${String(date.getDate()).padStart(2, "0")}`;
}

export function formatRuDate(date: Date): string {
  return `${String(date.getDate()).padStart(2, "0")}.${String(date.getMonth() + 1).padStart(2, "0")}.${date.getFullYear()}`;
}

export function mondayOfWeek(date: Date): Date {
  const copy = new Date(date);
  copy.setHours(0, 0, 0, 0);
  const mondayBasedDay = (copy.getDay() + 6) % 7;
  copy.setDate(copy.getDate() - mondayBasedDay);
  return copy;
}

export function sundayOfWeek(date: Date): Date {
  return addDays(mondayOfWeek(date), 6);
}

export function formatRuWeekRange(date: Date): string {
  return `${formatRuDate(mondayOfWeek(date))} - ${formatRuDate(sundayOfWeek(date))}`;
}