/**
  * @param \Ilis\Bundle\PaymentBundle\Entity\Transaction\Paypal $transaction
  * @throws Exception
  * @return string
  */
 public function buildUrl(PaypalTransaction $transaction)
 {
     switch ($transaction->getType()) {
         case PaypalTransaction::TYPE_BUYNOW:
             return $this->buildBuyNowUrl($transaction);
             break;
         default:
             throw new Exception(sprintf('Unhandled transaction type "%s"', $transaction->getType()));
     }
 }