Resolve #3321699 "Active trail initial visible level title"

Closes #3321699

src/Plugin/Block/MenuBlock.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\menu_block\Plugin\Block;
 
+use Drupal\Component\Render\MarkupInterface;
 use Drupal\Core\Access\AccessResult;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Link;
@@ -31,6 +32,7 @@ class MenuBlock extends SystemMenuBlock {
    */
   const LABEL_BLOCK = 'block';
   const LABEL_MENU = 'menu';
+  const LABEL_VISIBILITY_LEVEL_PARENT = 'visibility_level_parent';
   const LABEL_ACTIVE_ITEM = 'active_item';
   const LABEL_PARENT = 'parent';
   const LABEL_ROOT = 'root';
@@ -57,6 +59,11 @@ class MenuBlock extends SystemMenuBlock {
    */
   protected $buildCache;
 
+  /**
+   * Instance reference to the derived menu root.
+   */
+  protected string $menuRoot;
+
   /**
    * {@inheritdoc}
    */
@@ -129,6 +136,7 @@ class MenuBlock extends SystemMenuBlock {
       '#options' => [
         self::LABEL_BLOCK => $this->t('Block title'),
         self::LABEL_MENU => $this->t('Menu title'),
+        self::LABEL_VISIBILITY_LEVEL_PARENT => $this->t('Parent title at initial visibility level'),
         self::LABEL_FIXED => $this->t("Fixed parent item's title"),
         self::LABEL_ACTIVE_ITEM => $this->t("Active item's title"),
         self::LABEL_PARENT => $this->t("Active trail's parent title"),
@@ -151,6 +159,7 @@ class MenuBlock extends SystemMenuBlock {
           ':input[name="settings[label_display]"]' => ['checked' => TRUE],
           ':input[name="settings[label_type]"]' => [
             ['value' => self::LABEL_ACTIVE_ITEM],
+            ['value' => self::LABEL_VISIBILITY_LEVEL_PARENT],
             ['value' => self::LABEL_PARENT],
             ['value' => self::LABEL_ROOT],
             ['value' => self::LABEL_FIXED],
@@ -325,8 +334,8 @@ class MenuBlock extends SystemMenuBlock {
         // root based on the parent of the configured start level.
         $menu_trail_ids = array_reverse(array_values($parameters->activeTrail));
         $offset = ($following && $follow_parent == 'active') ? 2 : 1;
-        $menu_root = $menu_trail_ids[$level - $offset];
-        $parameters->setRoot($menu_root);
+        $this->menuRoot = $menu_trail_ids[$level - $offset];
+        $parameters->setRoot($this->menuRoot);
         if ($following || !$render_parent) {
           $parameters->setMinDepth(1);
         }
@@ -487,6 +496,9 @@ class MenuBlock extends SystemMenuBlock {
       case self::LABEL_PARENT:
         return $this->getActiveTrailParentTitle();
 
+      case self::LABEL_VISIBILITY_LEVEL_PARENT:
+        return $this->getVisibilityLevelParentTitle();
+
       case self::LABEL_ROOT:
         return $this->getActiveTrailRootTitle();
 
@@ -582,6 +594,22 @@ class MenuBlock extends SystemMenuBlock {
     return NULL;
   }
 
+  /**
+   * Gets the current menu item visibility level parent menu item title.
+   */
+  protected function getVisibilityLevelParentTitle(): MarkupInterface|string|null {
+    $active_trail_ids = $this->getDerivativeActiveTrailIds();
+
+    if ($active_trail_ids) {
+      if ($this->menuRoot && in_array($this->menuRoot, $active_trail_ids)) {
+        $active_trail_ids = [$this->menuRoot];
+      }
+      return $this->getLinkTitleFromLink(end($active_trail_ids));
+    }
+
+    return NULL;
+  }
+
   /**
    * Gets an array of the active trail menu link items.
    *
@@ -599,10 +627,10 @@ class MenuBlock extends SystemMenuBlock {
    * @param string $link_id
    *   The menu item ID.
    *
-   * @return string|null
-   *   The menu item title or NULL if the given menu item can't be found.
+   * @return string|\Drupal\Component\Render\MarkupInterface|null
+   *   The menu item title, link, or NULL if the given menu item can't be found.
    */
-  protected function getLinkTitleFromLink(string $link_id) {
+  protected function getLinkTitleFromLink(string $link_id): MarkupInterface|string|null {
     // Get the actual parameters so we have the active trail.
     $menu_name = $this->getDerivativeId();
     $parameters = $this->menuTree->getCurrentRouteMenuTreeParameters($menu_name);