CNPJ Validator PHP

cnpj-validator.php

<?php

namespace App\Domain\Shared\Validators;

class CnpjValidator
{
    public static function execute(string $cnpj): bool
    {
        $cnpj = str_pad($cnpj, 14, '0', STR_PAD_LEFT);

        if (strlen($cnpj) != 14) {
            return false;
        }

        // check if all digits are the same like: 11111111111111
        if (preg_match('/(\d)\1{13}/', $cnpj))
            return false;

        // check the first verification digit
        /**
         * @var int $i
         * @var int $j
         * @var int $sum
         * @var int $sum2
         * @var float $rest
         */
        for ($i = 0, $j = 5, $sum = 0; $i < 12; $i++) {
            $sum += ((int)$cnpj[$i] * $j);
            $j = ($j == 2) ? 9 : $j - 1;
        }

        $rest = $sum % 11;

        if ($cnpj[12] != ($rest < 2 ? 0 : 11 - $rest))
            return false;

        // check the second verification digit
        for ($i = 0, $j = 6, $sum2 = 0; $i < 13; $i++) {
            $sum2 += ((int)$cnpj[$i] * $j);
            $j = ($j == 2) ? 9 : ($j - 1);
        }

        $rest = $sum2 % 11;

        return $cnpj[13] == ($rest < 2 ? 0 : 11 - $rest);
    }
}