type NonZeroIntegers = 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9;
type Year = `${NonZeroIntegers}${NonZeroIntegers}${0 | NonZeroIntegers}${0 | NonZeroIntegers}`;

/**
 * Takes a string or number value and returns a string value formatted as a valid 4-digit year
 *
 * @export
 * @param {(string | number)} yearInput
 * @return {*}  {(Year | null)}
 */
export function normalizeExpiryYearFormat(yearInput: string | number): Year | null {
  // The input[type="number"] is returning a number, convert it to a string
  // An empty field returns null, avoid casting `"null"` to a string
  const yearInputIsEmpty = yearInput == null || yearInput === "";
  let expirationYear = yearInputIsEmpty ? null : `${yearInput}`;

  // Exit early if year is already formatted correctly or empty
  if (yearInputIsEmpty || /^[1-9]{1}\d{3}$/.test(expirationYear)) {
    return expirationYear as Year;
  }

  expirationYear = expirationYear
    // For safety, because even input[type="number"] will allow decimals
    .replace(/[^\d]/g, "")
    // remove any leading zero padding (leave the last leading zero if it ends the string)
    .replace(/^[0]+(?=.)/, "");

  if (expirationYear === "") {
    expirationYear = null;
  }

  // given the context of payment card expiry, a year character length of 3, or over 4
  // is more likely to be a mistake than an intentional value for the far past or far future.
  if (expirationYear && expirationYear.length !== 4) {
    const paddedYear = ("00" + expirationYear).slice(-2);
    const currentCentury = `${new Date().getFullYear()}`.slice(0, 2);

    expirationYear = currentCentury + paddedYear;
  }

  return expirationYear as Year | null;
}