import { createHash } from 'node:crypto';

/**
 * Compute a stable fingerprint of a screen's element set.
 * Sorted so insertion-order changes (React re-renders) don't produce false positives.
 * Returns first 16 hex chars of SHA-256.
 */
export function computeElementHash(
  elements: Array<{ role: string; meaning: string }>,
): string {
  const pairs = elements
    .map((e) => `${e.role.toLowerCase()}:${e.meaning.toLowerCase().trim()}`)
    .sort()
    .join('|');
  return createHash('sha256').update(pairs).digest('hex').slice(0, 16);
}