Laravel Validator Extension for Image Data URI

Base64DataUri.php

<?php
namespace App\Helper\ValidatorExtensions;

use Illuminate\Support\Facades\Validator;

/**
 * Validator Extension registration on Laravel AppServiceProvider.php:
 * => Validator::extend('is_base64_image_data', 'App\Helper\ValidatorExtensions\Base64DataUri@validate'); 
 * => Validator::replacer('is_base64_image_data', 'App\Helper\ValidatorExtensions\Base64DataUri@replacer');
 * Usage on Controller:
 * => $validator = Validator::make($request->all(), ['image_uri' => 'required|string|is_base64_image_data:image/png,image/jpeg']);
 * Laravel language translation (validation.php):
 * => 'is_base64_image_data' => ':Attribute should be an image data URL which encoded using base64 (Allowed mime-type: :values)',
 */
class Base64DataUri{

    public function validate($attribute, $value, $params, $validator) {
        $allowed_mimetype = array_intersect($params, ['image/png', 'image/jpeg', 'image/jpg', 'image/gif', 'image/bmp', 'image/webp']);
        $base64_header_format= "data:{mime};base64,";
        $data = null;
        $image = null;
        foreach($allowed_mimetype as $mime){
            $current_header_format = str_replace("{mime}", $mime, $base64_header_format);
            if(strpos($value, $current_header_format) !== false){
                $data = str_replace($current_header_format, "", $value);
                $data = str_replace(' ', '+', $data);
                $image = base64_decode($data);
                break;
            }
        }

        if ($image == null) return false;
        $f = finfo_open();
        $result = finfo_buffer($f, $image, FILEINFO_MIME_TYPE);
        // Due to some server encoding issue, we need to keep `application/octet-stream` as valid mime-type
        return in_array($result, array_merge(["application/octet-stream"], $allowed_mimetype));
    }

    public function replacer ($message, $attribute, $rule, $params) {
        return str_replace(':values', implode(', ', $params), $message);
    }
}