{#
/**
 * @file
 * Theme override to display a menu.
 *
 * Available variables:
 * - menu_name: The machine name of the menu.
 * - items: A nested list of menu items. Each menu item contains:
 *   - attributes: HTML attributes for the menu item.
 *   - below: The menu item child items.
 *   - title: The menu link title.
 *   - url: The menu link URL, instance of \Drupal\Core\Url
 *   - localized_options: Menu link localized options.
 *   - is_expanded: TRUE if the link has visible children within the current
 *     menu tree.
 *   - is_collapsed: TRUE if the link has children within the current menu tree
 *     that are not currently visible.
 *   - in_active_trail: TRUE if the link is in the active trail.
 */
#}

{% import _self as menus %}

{#
  We call a macro which calls itself to render the full tree.
  @see https://twig.symfony.com/doc/3.x/tags/macro.html

  1. We use menu_name (see above) to create a CSS class name from it.
  See https://www.drupal.org/node/2649076
#}
{{ menus.menu_links(items, attributes, 0, menu_name) }} {# 1. #}

{% macro menu_links(items, attributes, menu_level, menu_name) %} {# 1. #}
  {% import _self as menus %}
  {# 1. #}
  {%
    set menu_classes = [
      'menu-' ~ menu_name|clean_class,
    ]
  %}
  {# 1. #}
  {%
    set submenu_classes = [
      'menu-' ~ menu_name|clean_class ~ '__submenu',
    ]
  %}
  {% if items %}
    {% if menu_level == 0 %}
      <ul{{ attributes.addClass(menu_classes) }}> {# 1. #}
    {% else %}
      <ul{{ attributes.removeClass(menu_classes).addClass(submenu_classes) }}> {# 1. #}
    {% endif %}
    {% for item in items %}
      {# 1. #}
      {%
        set item_classes = [
          'menu-' ~ menu_name|clean_class ~ '__item',
          item.is_expanded ? 'menu-' ~ menu_name|clean_class ~ '__item--expanded',
          item.is_collapsed ? 'menu-' ~ menu_name|clean_class ~ '__item--collapsed',
          item.in_active_trail ? 'menu-' ~ menu_name|clean_class ~ '__item--active-trail',
        ]
      %}
      {# 1. #}
      {%
        set link_classes = [
          'menu-' ~ menu_name|clean_class ~ '__link',
        ]
      %}
      <li{{ item.attributes.addClass(item_classes) }}>{# 1. #}
        {# 1. #}
        {{
          link(
            item.title,
            item.url,
            item.attributes.removeClass(item_classes).addClass(link_classes)
          )
        }}
        {% if item.below %}
          {{ menus.menu_links(item.below, attributes, menu_level + 1, menu_name) }} {# 1. #}
        {% endif %}
      </li>
    {% endfor %}
    </ul>
  {% endif %}
{% endmacro %}