import * as z from "zod";

const CLOCK_TIME = /^([01]\d|2[0-3]):([0-5]\d)$/;

/** A 24-hour wall-clock time, e.g. "22:30". */
export const ClockTimeSchema = z.string().regex(CLOCK_TIME, "Use HH:MM");

/** Minutes after midnight for a "HH:MM" time. */
export function clockTimeToMinutes(value: string): number {
  const match = CLOCK_TIME.exec(value);
  if (!match) throw new Error("Use HH:MM");
  return Number(match[1]) * 60 + Number(match[2]);
}

/** "HH:MM" for minutes after midnight. */
export function minutesToClockTime(minutes: number): string {
  const pad = (value: number) => String(value).padStart(2, "0");
  return `${pad(Math.floor(minutes / 60))}:${pad(minutes % 60)}`;
}