import type { CreditCardBrand } from '../../../index';

/**
 * Calculates the credit card type.
 * Extracted from https://locastic.com/blog/how-to-check-credit-card-type-with-javascript
 */
export function getCreditCardBrand(cardNumber: string): CreditCardBrand {
  const cc = cardNumber.replace(/ /g, '');

  let amex = new RegExp('^3[47][0-9]{13}$'); // starts with 34 or 37 [15 digits]
  let visa = new RegExp('^4[0-9]{12}(?:[0-9]{3})?$'); // if it starts with a 4 it’s a Visa [16 digits (13 in some special cases)]

  let mastercard = new RegExp('^5[1-5][0-9]{14}$'); // First 2 digits can range from 51 to 55, but as mentioned above since 2017.  they also cover the 2221-2720 range [luckily in both cases 16 digits]
  let mastercard2 = new RegExp('^2[2-7][0-9]{14}$');

  let disco1 = new RegExp('^6011[0-9]{12}[0-9]*$'); // if it starts with 64 or 65 [16–19 digits] it’s definitely Discover, but… It can also start with any of these 6011, 622126 – 622925, 624000 – 626999, 628200 – 628899 (😭 )
  let disco2 = new RegExp('^62[24568][0-9]{13}[0-9]*$');
  let disco3 = new RegExp('^6[45][0-9]{14}[0-9]*$');

  let diners = new RegExp('^3[0689][0-9]{12}[0-9]*$'); // 36 definitely Diners [14-19 digits], but also 300–305, 3095, 38–39 [note that these range from 16-19 digits]
  let jcb = new RegExp('^35[0-9]{14}[0-9]*$'); //covers the range 3528-3589 [16–19 digits]

  let uatp = new RegExp('^1[0-9]{14}$'); // UATP cards are 15 digits and start with a 1

  if (visa.test(cc)) {
    return 'visa';
  }
  if (amex.test(cc)) {
    return 'american_express';
  }
  if (mastercard.test(cc) || mastercard2.test(cc)) {
    return 'mastercard';
  }
  if (disco1.test(cc) || disco2.test(cc) || disco3.test(cc)) {
    return 'discover';
  }
  if (diners.test(cc)) {
    return 'diners_club';
  }
  if (jcb.test(cc)) {
    return 'jcb';
  }
  if (uatp.test(cc)) {
    return 'uatp';
  }
  return '';
}