Add 403 login suggestion and redirection

modules/login/jsx/loginIndex.js

@@ -136,9 +136,11 @@ class Login extends Component {
       })
       .then((response) => {
         if (response.ok) {
-          response.json().then((data) => {
-            // success - refresh page and user is logged in.
-            window.location.href = window.location.origin;
+          response.json().then(() => {
+            // Redirect if there is a "redirect" param, refresh the page otherwise
+            window.location.href = this.props.redirect !== null
+              ? this.props.redirect
+              : window.location.origin;
           });
         } else {
           response.json().then((data) => {
@@ -353,6 +355,7 @@ window.addEventListener('load', () => {
       defaultRequestFirstName={getParam('firstname', '')}
       defaultRequestLastName={getParam('lastname', '')}
       defaultRequestEmail={getParam('email', '')}
+      redirect={getParam('redirect', null)}
       module={'login'}
     />
   );

smarty/templates/403.tpl

@@ -1,4 +1,11 @@
 <div class="container">
+    <h2>403: Forbidden</h2>
     <h3>{$message}</h3>
-    <div><a href="{$baseurl}">Go to main page</a> | <a onclick="window.history.back();" href="#">Go back one page</a></div>
+    <div>
+        <a href="{$baseurl}">Go to main page</a>
+        | <a onclick="window.history.back();" href="#">Go back one page</a>
+        {if $anonymous}
+            | <a href="/login?redirect={$url}">Try logging in</a>
+        {/if}
+    </div>
 </div>

src/Http/Error.php

@@ -55,6 +55,11 @@ public function __construct(
         $lorisInstance = $request->getAttribute('loris');
         $user          = $request->getAttribute('user') ?? new \LORIS\AnonymousUser();
 
+        // Variables used to suggest the user to login and later redirect them if they
+        // are not authenticated in a 403.
+        $tpl_data['anonymous'] = $user instanceof \LORIS\AnonymousUser;
+        $tpl_data['url']       = urlencode($_SERVER['REQUEST_URI']);
+
         // Add a link to the issue tracker as long as a LORIS Instance object
         // is present in the request.
         if (! $user instanceof \LORIS\AnonymousUser