Авторизация приложения и получение токена allegro.pl по API

<?
class Parser
{

    public $token;
    public $authUrl      = "https://allegro.pl/auth/oauth/token?grant_type=client_credentials";
    public $clientId     = "xxxxxxxx";
    public $clientSecret = "xxxxxxxx";


    //Авторизация приложения и получение токена
    public function getAccessTokenAllegro()
    {
        $ch = curl_init($this->authUrl);
        curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
        curl_setopt($ch, CURLOPT_USERNAME, $this->clientId);
        curl_setopt($ch, CURLOPT_PASSWORD, $this->clientSecret);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        $tokenResult = curl_exec($ch);
        $resultCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        if ($tokenResult === false || $resultCode !== 200) {
            exit ("Something went wrong");
        }

        $tokenObject = json_decode($tokenResult);
        $this->token = $tokenObject->access_token;
    }
}