Validate card numbers using Regex and a Luhn Check

validateCardNumber.php

<?php

class Operations {

    const PATTERN_AMERICAN_EXPRESS = "/^3[47][0-9]{13}$/";
    const PATTERN_DINERS_CLUB = "/^3(?:0[0-5]|[68][0-9])[0-9]{11}$/";
    const PATTERN_DISCOVER = "/^6(?:011|5[0-9]{2})[0-9]{12}$/";
    const PATTERN_JCB = "/^(?:2131|1800|35[0-9]{3})[0-9]{11}$/";
    const PATTERN_MASTERCARD = "/^(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}$/";
    const PATTERN_VERVE = "/^((506(0|1))|(507(8|9))|(6500))[0-9]{12,15}$/";
    const PATTERN_VISA = "/^4[0-9]{12}(?:[0-9]{3})?$/";
    
    public function can_be_string($var)
    {
        return $var === null || is_scalar($var) || (is_object($var) && method_exists($var, '__toString'));
    }

    public function is_valid_luhn($number)
    {
        $sumTable = [
            [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
            [0, 2, 4, 6, 8, 1, 3, 5, 7, 9],
        ];
        $sum = 0;
        $flip = 0;
        for ($i = strlen($number) - 1; $i >= 0; $i--) {
            $sum += $sumTable[$flip++ & 0x1][$number[$i]];
        }
        return $sum % 10 === 0;
    }

    public function cardType($number)
    {
        $cardtype = 'Unknown';
        // only values that can be converted to string can be checked
        if (!$this->can_be_string($number)) {
            return $cardtype;
        }
        $number = strval($number);
        $number = preg_replace("/[^0-9]/", "", $number);
        // only non-zero length strings can be checked
        if (!strlen($number)) {
            return $cardtype;
        }
        if (preg_match(Operations::PATTERN_MASTERCARD, $number)) {
            $cardtype = 'mastercard';
        } elseif (preg_match(Operations::PATTERN_VERVE, $number)) {
            $cardtype = 'verve';
        } elseif (preg_match(Operations::PATTERN_VISA, $number)) {
            $cardtype = 'visa';
        } elseif (preg_match(Operations::PATTERN_DINERS_CLUB, $number)) {
            $cardtype = 'Diners Club';
        } elseif (preg_match(Operations::PATTERN_DISCOVER, $number)) {
            $cardtype = 'Discover';
        } elseif (preg_match(Operations::PATTERN_AMERICAN_EXPRESS, $number)) {
            $cardtype = 'American Express';
        } elseif (preg_match(Operations::PATTERN_JCB, $number)) {
            $cardtype = 'JCB';
        }
        $cardtype = $this->is_valid_luhn($number) ? $cardtype : 'Unknown';
        return $cardtype;
    }
}