Issue #2796549 by hampercm, TorreyToomajanian: Alexa webhook fails due to multiple issues

namespace Drupal\alexa_webhook\Controller;

use Alexa\Request\Certificate;

use Drupal\alexa_webhook\AlexaEvent;

use Drupal\Core\Controller\ControllerBase;

use Symfony\Component\HttpFoundation\JsonResponse;

use Symfony\Component\HttpFoundation\Request;

use GuzzleHttp\Client;

use GuzzleHttp\Exception\RequestException;

use Alexa\Request\IntentRequest;

use Alexa\Request\LaunchRequest;

use Alexa\Response\Response;

use Drupal\alexa_webhook\AlexaEvent;

class AlexaWebhookController extends ControllerBase {

  /**

      try {

        // Use our own version of the Certificate class so we can implement

        // Drupal caching of a downloaded certificate.

        object_log('request', $request->headers->get('signature'));

        $certificate = new DrupalCertificate($request->headers->get('signaturecertchainurl'), $request->headers->get('signature'));

        $config = \Drupal::config('alexa_webhook.settings');

        // Parse and validate the request.

        $alexaRequest = $alexa->fromData();

      } catch (InvalidArgumentException $e) {

        // @TODO this is not firing up so any invalid requests will just PHP Error for now

        echo $e->getMessage();

      }

        $response = new \Alexa\Response\Response;

        $dispatcher = \Drupal::service('event_dispatcher');

      $e = new AlexaEvent($alexaRequest, $response);

      $event = $dispatcher->dispatch('alexaevent.request', $e);

        $event = new AlexaEvent($alexaRequest, $response);

        $dispatcher->dispatch('alexaevent.request', $event);

        return new JsonResponse($response->render());

      }

      catch (\InvalidArgumentException $e) {

        watchdog_exception('alexa_webhook', $e);

      }

    }

    return new JsonResponse(NULL, 500);

  }

}

/**

 * Overload the default Amazon Alexa App library Certificate class to allow

  * Drupal based caching of the downloaded Amazon certificate.

 * Drupal-based caching of the downloaded Amazon certificate.

 */

class DrupalCertificate extends \Alexa\Request\Certificate {

class DrupalCertificate extends Certificate {

  public function getCertificate() {

    $cid = 'alexa:certificate:' . $this->certificateUrl;

    $certificate = NULL;