/**
 * One world seed per epoch-relative period.
 * slot = floor((nowSec - epochSec) / rotationSeconds).
 * Changing timing config resets epochSec, which resets the slot to 0.
 */
export function computeWorldSeedState(rotationSeconds, epochSec) {
  const rot = Math.max(1, Math.floor(rotationSeconds));
  const epoch = Math.max(0, Math.floor(epochSec));
  const nowSec = Math.floor(Date.now() / 1000);
  const elapsed = Math.max(0, nowSec - epoch);
  const slot = Math.floor(elapsed / rot);
  const periodStart = epoch + slot * rot;
  const periodEnd = periodStart + rot;
  return {
    worldSeed: `swg-${epoch}-${slot}`,
    seedSlot: slot,
    seedPeriodEndsAtUtc: new Date(periodEnd * 1000).toISOString(),
    seedPeriodStartsAtUtc: new Date(periodStart * 1000).toISOString(),
  };
}