check if user is authentified and exist

src/Application/Middleware/AuthMiddleware.php

+<?php
+declare(strict_types=1);
+
+namespace App\Application\Middleware;
+
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface as Request;
+use Psr\Http\Server\MiddlewareInterface as Middleware;
+use Psr\Http\Server\RequestHandlerInterface as RequestHandler;
+use Slim\Psr7\Response;
+use Doctrine\ORM\EntityManager;
+
+class AuthMiddleware implements Middleware
+{
+    /**
+     * @var UserRepository
+     */
+    protected $userRepository;
+
+    /**
+     * Constructor.
+     *
+     * @param EntityManager $em The entity manager
+     */
+    public function __construct(EntityManager $em)
+    {
+        $this->userRepository = $em->getRepository('App\Domain\User\User');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function process(Request $request, RequestHandler $handler): ResponseInterface
+    {
+        if (isset($_SESSION['userId'])) {
+            $user = $this->userRepository->find($_SESSION['userId']);
+
+            if ($user === false) {
+                session_unset();
+            } else {
+                return $handler->handle($request);
+            }
+        }
+
+        $response = new Response();
+        return $response->withHeader('Location', '/login')->withStatus(302);
+    }
+}