/**
 * Normalize collector numbers so "015/208" and "15/208" compare equal.
 */
export function normalizeCardNumber(value) {
  if (value == null || value === '') return '';
  const trimmed = String(value).trim();
  const slashIndex = trimmed.indexOf('/');
  if (slashIndex === -1) {
    return trimmed.toLowerCase();
  }

  const numerator = trimmed.slice(0, slashIndex).trim();
  const denominator = trimmed.slice(slashIndex + 1).trim();
  const normalizedNumerator = String(parseInt(numerator, 10));
  if (normalizedNumerator === 'NaN') {
    return trimmed.toLowerCase();
  }

  return `${normalizedNumerator}/${denominator}`.toLowerCase();
}

export function cardNumbersEquivalent(a, b) {
  if (a == null || b == null || a === '' || b === '') return false;
  return normalizeCardNumber(a) === normalizeCardNumber(b);
}

/**
 * Pick one catalog row when name+set candidates share an equivalent collector number.
 */
export function findPrintingByCollectorNumber(candidates, cardNumber) {
  if (!cardNumber || candidates.length === 0) return null;

  const matches = candidates.filter((row) => cardNumbersEquivalent(row.card_number, cardNumber));
  return matches.length === 1 ? matches[0] : null;
}