export const DAY = 86_400_000;
export function dateIndex(date: string) {
  if (!/^\d{4}-\d{2}-\d{2}$/.test(date)) return NaN;
  const timestamp = Date.parse(`${date}T00:00:00Z`);
  return Number.isFinite(timestamp) &&
    new Date(timestamp).toISOString().slice(0, 10) === date
    ? timestamp / DAY
    : NaN;
}
export const indexDate = (index: number) =>
  new Date(index * DAY).toISOString().slice(0, 10);
export const addDays = (date: string, days: number) =>
  indexDate(dateIndex(date) + days);
export function timestampDate(value: unknown) {
  if (typeof value !== "number" || !Number.isFinite(value)) return "";
  const date = new Date(value);
  if (!Number.isFinite(date.getTime())) return "";
  return `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, "0")}-${String(date.getDate()).padStart(2, "0")}`;
}
export const todayDate = () => timestampDate(Date.now());
export const dateTimestamp = (date: string, end = false) =>
  Number.isFinite(dateIndex(date))
    ? new Date(`${date}T${end ? "23:59:59.999" : "00:00:00"}`).getTime()
    : null;