public function handle($post)
 {
     if (!isset($post['event']) || !isset($post['sign'])) {
         throw new Paysera_WalletApi_Exception_CallbackException('At least one of required parameters is missing');
     }
     $event = $post['event'];
     $sign = $post['sign'];
     if (!$this->callbackSignChecker->checkSign($event, $sign)) {
         throw new Paysera_WalletApi_Exception_CallbackException('Sign validation failed');
     }
     $eventData = json_decode($event, true);
     try {
         if ($eventData['object'] === 'transaction') {
             $subject = new Paysera_WalletApi_Event_TransactionEvent($this->mapper->decodeTransaction($eventData['data']));
         } elseif ($eventData['object'] === 'payment') {
             $subject = new Paysera_WalletApi_Event_PaymentEvent($this->mapper->decodePayment($eventData['data']));
         } elseif ($eventData['object'] === 'allowance') {
             $subject = new Paysera_WalletApi_Event_AllowanceEvent($this->mapper->decodeAllowance($eventData['data']));
         } else {
             throw new Paysera_WalletApi_Exception_CallbackUnsupportedException('Unknown event object');
         }
     } catch (Paysera_WalletApi_Exception_CallbackException $exception) {
         throw $exception;
         // just pass callback exceptions
     } catch (Exception $exception) {
         throw new Paysera_WalletApi_Exception_CallbackException('Exception caught while trying to decode event subject', 0, $exception);
     }
     $eventKey = $eventData['object'] . '.' . $eventData['type'];
     $this->eventDispatcher->dispatch($eventKey, $subject);
 }