added translations

frontend/src/Controller/LanguageController.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace App\Controller;
+
+use App\EventSubscriber\LocaleSubscriber;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\DependencyInjection\Attribute\Autowire;
+use Symfony\Component\HttpFoundation\Cookie;
+use Symfony\Component\HttpFoundation\RedirectResponse;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\Routing\Attribute\Route;
+
+class LanguageController extends AbstractController
+{
+    /** @param list<string> $enabledLocales */
+    public function __construct(
+        #[Autowire('%kernel.enabled_locales%')]
+        private readonly array $enabledLocales,
+    ) {
+    }
+
+    /** Remembers the chosen language in a cookie and returns to the page it was chosen on. */
+    #[Route('/language/{locale}', name: 'language_switch', requirements: ['locale' => '[a-z]{2}'])]
+    public function switch(string $locale, Request $request): RedirectResponse
+    {
+        if (!\in_array($locale, $this->enabledLocales, true)) {
+            throw $this->createNotFoundException();
+        }
+
+        // Only ever back to a path on this site — never an open redirect.
+        $back = (string) $request->query->get('back', '/');
+        if (!str_starts_with($back, '/') || str_starts_with($back, '//') || str_contains($back, '\\')) {
+            $back = '/';
+        }
+
+        $response = $this->redirect($back);
+        $response->headers->setCookie(Cookie::create(LocaleSubscriber::COOKIE, $locale, strtotime('+1 year'), '/', null, $request->isSecure(), false, false, Cookie::SAMESITE_LAX));
+
+        return $response;
+    }
+}