display skip links for first and second navigagion layer only when there are elements, fixes #4049

Closes #4049

Merge request studip/studip!2949


(cherry picked from commit cc617253)

233694ef display skip links for first and second navigagion layer only when there are elements
5da6f576 fixed third navigation layer on the start page

app/controllers/start.php

@@ -57,6 +57,7 @@ class StartController extends AuthenticatedController
 
         $nav = $sidebar->addWidget(new NavigationWidget());
         $nav->setTitle(_('Sprungmarken'));
+        $nav->setId('navigation-layer-3');
         foreach (array_merge(...$this->columns) as $widget) {
             $nav->addLink(
                 $widget->getPluginName(),

lib/classes/sidebar/Sidebar.php

@@ -222,7 +222,7 @@ class Sidebar extends WidgetContainer
         static $actions_widget_added = false;
 
 
-        if ($widget instanceof NavigationWidget && !$navigation_widget_added) {
+        if ($widget instanceof NavigationWidget && !$navigation_widget_added && $widget->hasElements()) {
             SkipLinks::addIndex(
                 _('Dritte Navigationsebene'),
                 $widget->getId(),
@@ -233,7 +233,7 @@ class Sidebar extends WidgetContainer
             $navigation_widget_added = true;
         }
 
-        if ($widget instanceof ActionsWidget && !$actions_widget_added) {
+        if ($widget instanceof ActionsWidget && !$actions_widget_added && $widget->hasElements()) {
             if (!$widget->getId()) {
                 $widget->setId('sidebar-actions');
             }

templates/header.php

@@ -216,7 +216,9 @@ if ($navigation) {
 
     <!-- Main navigation and right-hand logo -->
     <nav id="navigation-level-1" aria-label="<?= _('Hauptnavigation') ?>">
-        <? SkipLinks::addIndex(_('Hauptnavigation'), 'navigation-level-1', 2, false); ?>
+        <? if (!empty($header_nav['visible'])) : ?>
+            <? SkipLinks::addIndex(_('Hauptnavigation'), 'navigation-level-1', 2, false) ?>
+        <? endif ?>
         <ul id="navigation-level-1-items" <? if (count($header_nav['hidden']) > 0) echo 'class="overflown"'; ?>>
         <? foreach ($header_nav['visible'] as $path => $nav): ?>
             <?= $this->render_partial(
@@ -297,10 +299,12 @@ if ($navigation) {
                 </div>
             <? endif ?>
 
-            <? SkipLinks::addIndex(_('Zweite Navigationsebene'), 'navigation-level-2', 910) ?>
             <nav id="navigation-level-2" aria-label="<?= _('Zweite Navigationsebene') ?>">
 
                 <? if (PageLayout::isHeaderEnabled() /*&& isset($navigation)*/) : ?>
+                    <? if (!empty($navigation)) : ?>
+                        <? SkipLinks::addIndex(_('Zweite Navigationsebene'), 'navigation-level-2', 910) ?>
+                    <? endif ?>
                     <?= $this->render_partial('tabs', compact('navigation')) ?>
                 <? endif; ?>
             </nav>

templates/tabs.php

@@ -7,10 +7,10 @@ foreach (Navigation::getItem("/")->getSubNavigation() as $path => $nav) {
 }
 ?>
 <div class="tabs_wrapper">
-    <? SkipLinks::addIndex(_('Zweite Navigationsebene'), 'navigation-level-2', 10, false); ?>
     <ul id="tabs">
         <? if (!empty($navigation)): ?>
-        <? foreach ($navigation as $path => $nav) : ?>
+            <? SkipLinks::addIndex(_('Zweite Navigationsebene'), 'navigation-level-2', 10, false); ?>
+            <? foreach ($navigation as $path => $nav) : ?>
             <? if ($nav->isVisible()) : ?>
                 <li id="nav_<?= $path1 ?? '' ?>_<?= $path ?>"<?= $nav->isActive() ? ' class="current"' : '' ?>>
                     <? if ($nav->isEnabled()): ?>