Validate access tokens sent through Amazon Alexa requests

botman.php

<?php
/*
 * Example usage
 */
$botman->middleware->received(new CheckAccessToken());

$botman->hears('MyIntent', function (BotMan $bot) {
    $user = $bot->getMessage()->getExtras('user');
    return $bot->reply('Hello, '.$user->name, [
        'shouldEndSession' => true
    ]);
});

CheckAccessToken.php

<?php

namespace App\BotMan\Middleware;

use BotMan\BotMan\BotMan;
use Laravel\Passport\TokenRepository;
use League\OAuth2\Server\ResourceServer;
use Symfony\Component\HttpFoundation\Request;
use BotMan\Drivers\AmazonAlexa\Extensions\Card;
use BotMan\BotMan\Interfaces\Middleware\Received;
use BotMan\BotMan\Messages\Incoming\IncomingMessage;
use BotMan\BotMan\Messages\Outgoing\OutgoingMessage;
use League\OAuth2\Server\Exception\OAuthServerException;
use Symfony\Bridge\PsrHttpMessage\Factory\DiactorosFactory;

class CheckAccessToken implements Received
{

    const LINK_ACCOUNT_MESSAGE = 'Please link your account in your Alexa app.';

    /**
     * Handle an incoming message.
     *
     * @param IncomingMessage $message
     * @param callable $next
     * @param BotMan $bot
     *
     * @return mixed
     */
    public function received(IncomingMessage $message, $next, BotMan $bot)
    {
        /*
         * Get TokenRepository and ResourceServer from the IoC
         */
        $tokens = app(TokenRepository::class);
        $server = app(ResourceServer::class);

        $tokenString = array_get($message->getPayload(), 'session.user.accessToken');

        /*
         * Create a Symfony request to simulate an incoming request.
         */
        $request = Request::create('/', 'GET', [], [], [], ['HTTP_AUTHORIZATION' => 'Bearer '.$tokenString]);

        /*
         * Convert the Symfony request to a PSR compliant request and validate it manually
         */
        $request = (new DiactorosFactory)->createRequest($request);
        try {
            $psr = $server->validateAuthenticatedRequest($request);
        } catch (OAuthServerException $exception) {
            $reply = OutgoingMessage::create(self::LINK_ACCOUNT_MESSAGE)->withAttachment(Card::create(null)->type('LinkAccount'));

            return $bot->reply($reply);
        }

        /*
         * Next, retrieve the token for this JWT and store the user to the incoming message.
         */
        $token = $tokens->find(
            $psr->getAttribute('oauth_access_token_id')
        );

        $message->addExtras('user', $token->user);

        return $next($message);
    }
}