From ce1c8329f3384494eeabc70eb4943e7c479135eb Mon Sep 17 00:00:00 2001
From: Nikolay Lobachev <nikolay.lobachev@gmail.com>
Date: Wed, 10 Jun 2020 16:05:00 +0200
Subject: [PATCH] Take into account destination parameter in the request, pass
 so we can be redirected back.

---
 src/Controller/RegisterController.php | 97 ++++++++++++++++++++++++---
 1 file changed, 87 insertions(+), 10 deletions(-)

diff --git a/src/Controller/RegisterController.php b/src/Controller/RegisterController.php
index cc03a2e..3bc4e69 100644
--- a/src/Controller/RegisterController.php
+++ b/src/Controller/RegisterController.php
@@ -5,12 +5,15 @@
 namespace Drupal\oe_authentication\Controller;
 
 use Drupal\cas\Service\CasHelper;
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\Core\Routing\TrustedRedirectResponse;
 use Drupal\Core\Url;
+use Drupal\Core\Utility\UnroutedUrlAssemblerInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
 
 /**
@@ -18,6 +21,20 @@
  */
 class RegisterController extends ControllerBase {
 
+  /**
+   * The unrouted URL assembler service.
+   *
+   * @var \Drupal\Core\Utility\UnroutedUrlAssemblerInterface
+   */
+  protected $unroutedUrlAssembler;
+
+  /**
+   * The configuration factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
   /**
    * CAS Helper object.
    *
@@ -26,16 +43,29 @@ class RegisterController extends ControllerBase {
   protected $casHelper;
 
   /**
-   * Constructs the controller object.
+   * Request.
+   *
+   * @var \Symfony\Component\HttpFoundation\Request
+   */
+  protected $request;
+
+  /**
+   * Redirects to eulogin pages.
    *
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   The route match.
    * @param \Drupal\cas\Service\CasHelper $cas_helper
    *   The CAS Helper service.
    * @param \Drupal\Core\Config\ConfigFactoryInterface $configFactory
    *   The configuration factory.
+   * @param \Drupal\Core\Utility\UnroutedUrlAssemblerInterface $url_assembler
+   *   The unrouted URL assembler service.
    */
-  public function __construct(CasHelper $cas_helper, ConfigFactoryInterface $configFactory) {
+  public function __construct(Request $request, CasHelper $cas_helper, ConfigFactoryInterface $configFactory, UnroutedUrlAssemblerInterface $url_assembler) {
+    $this->request = $request;
     $this->casHelper = $cas_helper;
     $this->configFactory = $configFactory;
+    $this->unroutedUrlAssembler = $url_assembler;
   }
 
   /**
@@ -43,8 +73,10 @@ public function __construct(CasHelper $cas_helper, ConfigFactoryInterface $confi
    */
   public static function create(ContainerInterface $container) {
     return new static(
+      $container->get('request_stack')->getCurrentRequest(),
       $container->get('cas.helper'),
-      $container->get('config.factory')
+      $container->get('config.factory'),
+      $container->get('unrouted_url_assembler')
     );
   }
 
@@ -79,15 +111,60 @@ public function getRegisterUrl(): Url {
     $config = $this->configFactory->get('oe_authentication.settings');
     $base_url = $this->casHelper->getServerBaseUrl();
     $path = $config->get('register_path');
-    $service = Url::fromRoute('<front>');
-    $service->setAbsolute();
+    $destination = $this->request->query->get('destination');
+    if (!empty($destination)) {
+      $destination_path = $this->getDestinationAsAbsoluteUrl($destination);
+      // Remove destination parameter to avoid redirection.
+      $this->request->query->remove('destination');
+    }
+    else {
+      $front_url = Url::fromRoute('<front>');
+      $front_url->setAbsolute();
+      // We need to ensure we are collecting the cache metadata so it doesn't
+      // bubble up to the render context or we get a Logic exception later
+      // when we return a Cacheable response.
+      $front_url = $front_url->toString(TRUE);
+      $destination_path = $front_url->getGeneratedUrl();
+    }
 
-    // We need to ensure we are collecting the cache metadata so it doesn't
-    // bubble up to the render context or we get a Logic exception later
-    // when we return a Cacheable response.
-    $service = $service->toString(TRUE);
+    return Url::fromUri($base_url . $path, ['query' => ['service' => $destination_path]]);
+  }
 
-    return Url::fromUri($base_url . $path, ['query' => ['service' => $service->getGeneratedUrl()]]);
+  /**
+   * Converts the passed in destination into an absolute URL.
+   *
+   * @param string $destination
+   *   The path for the destination. In case it starts with a slash it should
+   *   have the base path included already.
+   *
+   * @return string
+   *   The destination as absolute URL.
+   */
+  protected function getDestinationAsAbsoluteUrl($destination) {
+    if (!UrlHelper::isExternal($destination)) {
+      // The destination query parameter can be a relative URL in the sense of
+      // not including the scheme and host, but its path is expected to be
+      // absolute (start with a '/'). For such a case, prepend the scheme and
+      // host, because the 'Location' header must be absolute.
+      if (strpos($destination, '/') === 0) {
+        $destination = $this->request->getSchemeAndHttpHost() . $destination;
+      }
+      else {
+        // Legacy destination query parameters can be internal paths that have
+        // not yet been converted to URLs.
+        $destination = UrlHelper::parse($destination);
+        $uri = 'base:' . $destination['path'];
+        $options = [
+          'query' => $destination['query'],
+          'fragment' => $destination['fragment'],
+          'absolute' => TRUE,
+        ];
+        // Treat this as if it's user input of a path relative to the site's
+        // base URL.
+        $destination = $this->unroutedUrlAssembler->assemble($uri, $options);
+      }
+    }
+    return $destination;
   }
 
 }