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

    public function validate($vatNumber)
    {
        if (strlen($vatNumber) != 9) {
            return false;
        }
        if (strtoupper($vatNumber[0]) != 'U') {
            return false;
        }
        $checksum = (int) $vatNumber[8];
        $checkval = 0;
        for ($i = 1; $i < 8; $i++) {
            $checkval += $this->crossSum((int) $vatNumber[$i] * ($this->isEven($i) ? 2 : 1));
        }
        $checkval = substr((string) (96 - $checkval), -1);
        if ($checksum != $checkval) {
            return false;
        }
        return true;
    }