/**
 * SH-356: a Due Date can never be earlier than Schedule On.
 *
 * The floor is the concrete Schedule On day, the start of a date range, or — for a
 * week-only schedule (SH-110) — the first day of the target week.
 */
export function resolveDueDateFloor(schedule: {
  scheduledOn?: string | null;
  targetWeek?: string | null;
}): string {
  return schedule.scheduledOn?.trim() || schedule.targetWeek?.trim() || "";
}

export function isDueDateBeforeFloor(dueDate: string | null | undefined, floor: string): boolean {
  return Boolean(dueDate && floor && dueDate < floor);
}

/**
 * Patch fragment for a Schedule On change: clears an existing Due Date that the new
 * schedule would leave in the past. Never bumps it to a guessed value.
 */
export function clearDueDateBeforeSchedule(
  dueDate: string | null | undefined,
  nextFloor: string,
): { dueDate?: string } {
  return isDueDateBeforeFloor(dueDate, nextFloor) ? { dueDate: "" } : {};
}