/* ============================================================
   Session 59 (work-order 2.3) — the REAL pipeline schedule, for honest
   waiting states. "Awaiting next scan" told the user nothing; the truth is
   the cron fires at fixed UTC hours, so we can say "Grades post ~6:00 PM ET".

   HOURS_UTC mirrors the backend default (snapshotScheduler SNAPSHOT_HOURS_UTC
   = 14,19,22,1,3). If the env schedule changes, update BOTH places — a wrong
   time here is a lie, which is worse than the old vague copy.

   CommonJS so the plain-JS Jest suite can require it directly.
   ============================================================ */

const HOURS_UTC = [14, 19, 22, 1, 3];

/** The next scheduled run strictly after `now`, as a Date. */
function nextRunAt(now = new Date(), hours = HOURS_UTC) {
  const candidates = [];
  for (let dayOffset = 0; dayOffset <= 1; dayOffset += 1) {
    for (const h of hours) {
      const d = new Date(now.getTime());
      d.setUTCDate(d.getUTCDate() + dayOffset);
      d.setUTCHours(h, 0, 0, 0);
      if (d.getTime() > now.getTime()) candidates.push(d);
    }
  }
  candidates.sort((a, b) => a.getTime() - b.getTime());
  return candidates[0] || null;
}

/** "~6:00 PM ET" for the next run. Empty string when the schedule is unknown. */
function nextRunLabelET(now = new Date(), hours = HOURS_UTC) {
  const next = nextRunAt(now, hours);
  if (!next) return '';
  const t = new Intl.DateTimeFormat('en-US', {
    timeZone: 'America/New_York', hour: 'numeric', minute: '2-digit',
  }).format(next);
  return `~${t} ET`;
}

module.exports = { HOURS_UTC, nextRunAt, nextRunLabelET };