import { knownTimeZone } from "./cron.js";

/** Minutes after local midnight; `start` > `end` means the range crosses midnight. */
export interface MinuteRange {
  start: number;
  end: number;
}

/** The local calendar date ("YYYY-MM-DD") and minute of day at `now`, UTC when the zone is unknown. */
export function localDateAndMinute(
  now: Date,
  timeZone: string | null | undefined,
): { date: string; minute: number } {
  const parts = new Map(
    new Intl.DateTimeFormat("en-US", {
      timeZone: knownTimeZone(timeZone) ?? "UTC",
      year: "numeric",
      month: "2-digit",
      day: "2-digit",
      hour: "2-digit",
      minute: "2-digit",
      hourCycle: "h23",
    })
      .formatToParts(now)
      .map((part) => [part.type, part.value]),
  );
  return {
    date: `${parts.get("year")}-${parts.get("month")}-${parts.get("day")}`,
    minute: Number(parts.get("hour")) * 60 + Number(parts.get("minute")),
  };
}

/** True when `minute` lies in the range; the start is inclusive, the end exclusive. */
export function isQuietMinute(range: MinuteRange | null, minute: number): boolean {
  if (!range || range.start === range.end) return false;
  return range.start < range.end
    ? minute >= range.start && minute < range.end
    : minute >= range.start || minute < range.end;
}

/** True when `now` falls in the quiet hours of a user in `timeZone`. */
export function isQuietTime(
  range: MinuteRange | null,
  timeZone: string | null | undefined,
  now: Date,
): boolean {
  return isQuietMinute(range, localDateAndMinute(now, timeZone).minute);
}