OAuth: show reduced login screen

data/web/index.php

@@ -31,7 +31,7 @@ $_SESSION['return_to'] = $_SERVER['REQUEST_URI'];
         <div class="panel-heading"><span class="glyphicon glyphicon-user" aria-hidden="true"></span> <?= $lang['login']['login']; ?></div>
         <div class="panel-body">
           <div class="text-center mailcow-logo"><img src="<?=($main_logo = customize('get', 'main_logo')) ? $main_logo : '/img/cow_mailcow.svg';?>" alt="mailcow"></div>
-          <legend><?=$UI_TEXTS['main_name'];?></legend>
+          <legend><?= isset($_SESSION['oauth2_request']) ? $lang['oauth2']['authorize_app'] : $UI_TEXTS['main_name'];?></legend>
             <form method="post" autofill="off">
             <div class="form-group">
               <label class="sr-only" for="login_user"><?= $lang['login']['username']; ?></label>
@@ -49,6 +49,7 @@ $_SESSION['return_to'] = $_SERVER['REQUEST_URI'];
             </div>
             <div class="form-group">
               <button type="submit" class="btn btn-success" value="Login"><?= $lang['login']['login']; ?></button>
+              <?php if(!isset($_SESSION['oauth2_request'])): ?>
               <div class="btn-group pull-right">
                 <button type="button" <?=(isset($_SESSION['mailcow_locale']) && count($AVAILABLE_LANGUAGES) === 1) ? 'disabled="true"' : '' ?> class="btn btn-default dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                   <span class="lang-sm lang-lbl" lang="<?= $_SESSION['mailcow_locale']; ?>"></span> <span class="caret"></span>
@@ -63,6 +64,7 @@ $_SESSION['return_to'] = $_SERVER['REQUEST_URI'];
                   ?>
                 </ul>
               </div>
+              <?php endif ?>
             </div>
             </form>
             <?php
@@ -72,6 +74,7 @@ $_SESSION['return_to'] = $_SERVER['REQUEST_URI'];
             <?php
             endif;
             ?>
+          <?php if(!isset($_SESSION['oauth2_request'])): ?>
           <legend><?=$UI_TEXTS['apps_name'];?></legend>
           <?php
           foreach ($MAILCOW_APPS as $app):
@@ -89,10 +92,12 @@ $_SESSION['return_to'] = $_SERVER['REQUEST_URI'];
               endforeach;
             }
           }
+          endif;
           ?>
         </div>
       </div>
     </div>
+    <?php if(!isset($_SESSION['oauth2_request'])): ?>
     <div class="col-md-offset-3 col-md-6">
       <div class="panel panel-default">
         <div class="panel-heading">
@@ -112,6 +117,7 @@ $_SESSION['return_to'] = $_SERVER['REQUEST_URI'];
         </div>
       </div>
     </div>
+    <?php endif ?>
   </div>
 </div><!-- /.container -->
 <?php