ABN Validation Rule

IsValidABN.php

<?php

namespace App\Rules;

use Illuminate\Contracts\Validation\Rule;

class IsValidABN implements Rule
{
    /**
     * Determine if the validation rule passes.
     *
     * @param  string  $attribute
     * @param  mixed  $value
     * @return bool
     */
    public function passes($attribute, $value)
    {
        $weights = [10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19];

        // strip anything other than digits
        $abn = preg_replace("/[^\d]/", '', $value);

        // check length is 11 digits
        if (strlen($abn) == 11) {
            // apply ATO check method
            $sum = 0;
            foreach ($weights as $position => $weight) {
                $digit = $abn[$position] - ($position ? 0 : 1);
                $sum += $weight * $digit;
            }

            return ($sum % 89) == 0;
        }

        return false;
    }

    /**
     * Get the validation error message.
     *
     * @return string
     */
    public function message()
    {
        return 'The provided ABN number is not valid.';
    }
}