// Reminder datetime helpers. Reminders are stored as ISO UTC; the editor's
// <input type="datetime-local"> works in local time.

export function toLocalInput(iso: string | null): string {
  if (!iso) return "";
  const d = new Date(iso);
  const pad = (n: number) => String(n).padStart(2, "0");
  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}`;
}

export function fromLocalInput(local: string): string | null {
  if (!local) return null;
  return new Date(local).toISOString();
}

export function formatReminder(iso: string | null): string {
  if (!iso) return "";
  return new Date(iso).toLocaleString(undefined, {
    month: "short",
    day: "numeric",
    hour: "numeric",
    minute: "2-digit",
  });
}

export function isOverdue(iso: string | null): boolean {
  return !!iso && new Date(iso).getTime() < Date.now();
}