DragonBe\Vies\Validator\ValidatorIT::validate PHP Method

    public function validate($vatNumber)
    {
        if (strlen($vatNumber) != 11) {
            return false;
        }
        if (substr($vatNumber, 0, 7) == '0000000') {
            return false;
        }
        $checksum = (int) substr($vatNumber, -1);
        $Sum1 = $Sum2 = 0;
        for ($i = 1; $i <= 10; $i++) {
            if (!$this->isEven($i)) {
                $Sum1 += $vatNumber[$i - 1];
            } else {
                $Sum2 += (int) ($vatNumber[$i - 1] / 5) + 2 * $vatNumber[$i - 1] % 10;
            }
        }
        $checkval = (10 - ($Sum1 + $Sum2) % 10) % 10;
        if ($checksum != $checkval) {
            return false;
        }
        return true;
    }