/**
 * Explicit card references in commit messages: `[#42]`.
 *
 * Brackets are required. A bare `#42` appears far too often in ordinary prose —
 * hex colours, issue numbers from other trackers, ordinals — and a linker that
 * guesses at those attaches work to the wrong card, which is worse than not
 * linking it at all.
 *
 * This is the override, not the daily habit: scope matching carries most
 * commits. It exists for the times auto-linking gets it wrong.
 */

/** Above this, the value is not a card number; it is a typo or an overflow. */
const MAX_CARD_NUMBER = 1_000_000;

const REFERENCE = /\[#\s*(\d+)\s*\]/;

export function extractCardReference(message: string): number | null {
  const match = REFERENCE.exec(message ?? "");
  if (!match) return null;

  const value = Number(match[1]);
  if (!Number.isInteger(value)) return null;
  if (value < 1 || value > MAX_CARD_NUMBER) return null;

  return value;
}