EU VAT-ID validation in PHP

EUVatService.php

<?php

namespace App\Services;

use Http;
use Log;

class EUVatService {
   /**
    * Check vat in EU interface
    */
   public static function isVatIdValid(string $vatId): ?bool {
      $countryCode = substr($vatId, 0, 2);

      // Regex pattern for EU VAT ID validation: 2 uppercase letters followed by any characters
      $pattern = '/^[A-Z]{2,}.*$/';

      $body = '';
      if (preg_match($pattern, $vatId) === 1) {
         $resp = Http::get("https://ec.europa.eu/taxation_customs/vies/rest-api/ms/$countryCode/vat/$vatId");
         $body = $resp->json();

         error_log(json_encode($body, JSON_PRETTY_PRINT));

         if ($body['isValid'] ?? false) {
            return true;
         }

         if ($body['userError'] === 'MS_MAX_CONCURRENT_REQ') {
            return null;
         }

         if ($body['userError'] === 'MS_UNAVAILABLE') {
            return null;
         }

         if ($body['userError'] === 'INVALID') {
            return false;
         }

         if ($body['userError'] === 'INVALID_INPUT') {
            return false;
         }
      } else {
         $body = "Provided vatId didn't match the base requirement pattern. Value: " . $vatId;
      }

      Log::debug('VatId check failed. Response: ', (array) $body);

      return null;
   }
}