WordPress child page submenu & ancestors

gistfile1.phtml

<?php
$ancestors = get_post_ancestors($post->ID);

if (empty($ancestors)) {
    $last_ancestor = $post->ID;
} else {
    $last_ancestor = $ancestors[count($ancestors) - 1];
}
?>

<ul class="sidebar-menu v-list text-center">
    <?php
    $nav_items = get_pages(array(
        'parent' => $last_ancestor,
        'post_status' => 'publish',
        'sort_column' => 'menu_order'
    ));
    
    foreach ($nav_items as $nav)
    {
        if ($post->ID == $nav->ID)
        {
            echo '<li class="current_page_item"><a href="' . get_permalink($nav->ID) . '">' . $nav->post_title . '</a>';
        }
        else
        {
            echo '<li><a href="' . get_permalink($nav->ID) . '">' . $nav->post_title . '</a>';
        }

        if ($post->ID == $nav->ID || (count($ancestors) > 1 && $post->post_parent == $ancestors[0]))
        {
            $child_nav_items = get_pages(array(
                'parent' => $nav->ID,
                'post_status' => 'publish',
                'sort_column' => 'menu_order'
            ));
            
            if ( count($child_nav_items) > 0) {
            
                echo '<ul class="sidebar-sub-menu v-list">';
            
                foreach($child_nav_items as $child_nav)
                {
                    if ($post->ID == $child_nav->ID)
                    {
                        echo '<li class="current_page_item"><a href="' . get_permalink($child_nav->ID) . '">' . $child_nav->post_title . '</a></li>';
                    }
                    else
                    {
                        echo '<li><a href="' . get_permalink($child_nav->ID) . '">' . $child_nav->post_title . '</a></li>';
                    }
                }
                echo '</ul>';
            }
        }
        echo '</li>';
    }
    ?>
</ul>