class LayoutBuilder

class LayoutBuilder extends RenderElementBase implements ContainerFactoryPluginInterface {
  use AjaxHelperTrait;
  use LayoutBuilderContextTrait;
  use LayoutBuilderHighlightTrait;

  /**
   * The event dispatcher.
   *
   * @var \Symfony\Contracts\EventDispatcher\EventDispatcherInterface
   */
  protected $eventDispatcher;

  /**
   * Constructs a new LayoutBuilder.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin ID for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Symfony\Contracts\EventDispatcher\EventDispatcherInterface $event_dispatcher
   *   The event dispatcher service.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, EventDispatcherInterface $event_dispatcher) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->eventDispatcher = $event_dispatcher;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container
      ->get('event_dispatcher'));
  }

  /**
   * {@inheritdoc}
   */
  public function getInfo() {
    return [
      '#section_storage' => NULL,
      '#pre_render' => [
        [
          $this,
          'preRender',
        ],
      ],
    ];
  }

  /**
   * Pre-render callback: Renders the Layout Builder UI.
   */
  public function preRender($element) {
    if ($element['#section_storage'] instanceof SectionStorageInterface) {
      $element['layout_builder'] = $this
        ->layout($element['#section_storage']);
    }
    return $element;
  }

  /**
   * Renders the Layout UI.
   *
   * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
   *   The section storage.
   *
   * @return array
   *   A render array.
   */
  protected function layout(SectionStorageInterface $section_storage) {
    $this
      ->prepareLayout($section_storage);
    $output = [];
    if ($this
      ->isAjax()) {
      $output['status_messages'] = [
        '#type' => 'status_messages',
      ];
    }
    $count = 0;
    for ($i = 0; $i < $section_storage
      ->count(); $i++) {
      $output[] = $this
        ->buildAddSectionLink($section_storage, $count);
      $output[] = $this
        ->buildAdministrativeSection($section_storage, $count);
      $count++;
    }
    $output[] = $this
      ->buildAddSectionLink($section_storage, $count);
    $output['#attached']['library'][] = 'layout_builder/drupal.layout_builder';

    // As the Layout Builder UI is typically displayed using the frontend theme,
    // it is not marked as an administrative page at the route level even though
    // it performs an administrative task. Mark this as an administrative page
    // for JavaScript.
    $output['#attached']['drupalSettings']['path']['currentPathIsAdmin'] = TRUE;
    $output['#type'] = 'container';
    $output['#attributes']['id'] = 'layout-builder';
    $output['#attributes']['class'][] = 'layout-builder';

    // Mark this UI as uncacheable.
    $output['#cache']['max-age'] = 0;
    return $output;
  }

  /**
   * Prepares a layout for use in the UI.
   *
   * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
   *   The section storage.
   */
  protected function prepareLayout(SectionStorageInterface $section_storage) {
    $event = new PrepareLayoutEvent($section_storage);
    $this->eventDispatcher
      ->dispatch($event, LayoutBuilderEvents::PREPARE_LAYOUT);
  }

  /**
   * Builds a link to add a new section at a given delta.
   *
   * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
   *   The section storage.
   * @param int $delta
   *   The delta of the section to splice.
   *
   * @return array
   *   A render array for a link.
   */
  protected function buildAddSectionLink(SectionStorageInterface $section_storage, $delta) {
    $storage_type = $section_storage
      ->getStorageType();
    $storage_id = $section_storage
      ->getStorageId();

    // If the delta and the count are the same, it is either the end of the
    // layout or an empty layout.
    if ($delta === count($section_storage)) {
      if ($delta === 0) {
        $title = $this
          ->t('Add section');
      }
      else {
        $title = $this
          ->t('Add section <span class="visually-hidden">at end of layout</span>');
      }
    }
    else {
      if ($delta === 0) {
        $title = $this
          ->t('Add section <span class="visually-hidden">at start of layout</span>');
      }
      else {
        $title = $this
          ->t('Add section <span class="visually-hidden">between @first and @second</span>', [
          '@first' => $delta,
          '@second' => $delta + 1,
        ]);
      }
    }
    return [
      'link' => [
        '#type' => 'link',
        '#title' => $title,
        '#url' => Url::fromRoute('layout_builder.choose_section', [
          'section_storage_type' => $storage_type,
          'section_storage' => $storage_id,
          'delta' => $delta,
        ], [
          'attributes' => [
            'class' => [
              'use-ajax',
              'layout-builder__link',
              'layout-builder__link--add',
            ],
            'data-dialog-type' => 'dialog',
            'data-dialog-renderer' => 'off_canvas',
          ],
        ]),
      ],
      '#type' => 'container',
      '#attributes' => [
        'class' => [
          'layout-builder__add-section',
        ],
        'data-layout-builder-highlight-id' => $this
          ->sectionAddHighlightId($delta),
      ],
    ];
  }

  /**
   * Builds the render array for the layout section while editing.
   *
   * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
   *   The section storage.
   * @param int $delta
   *   The delta of the section.
   *
   * @return array
   *   The render array for a given section.
   */
  protected function buildAdministrativeSection(SectionStorageInterface $section_storage, $delta) {
    $storage_type = $section_storage
      ->getStorageType();
    $storage_id = $section_storage
      ->getStorageId();
    $section = $section_storage
      ->getSection($delta);
    $layout = $section
      ->getLayout($this
      ->getPopulatedContexts($section_storage));
    $layout_settings = $section
      ->getLayoutSettings();
    $section_label = !empty($layout_settings['label']) ? $layout_settings['label'] : $this
      ->t('Section @section', [
      '@section' => $delta + 1,
    ]);
    $build = $section
      ->toRenderArray($this
      ->getPopulatedContexts($section_storage), TRUE);
    $layout_definition = $layout
      ->getPluginDefinition();
    $region_labels = $layout_definition
      ->getRegionLabels();
    foreach ($layout_definition
      ->getRegions() as $region => $info) {
      if (!empty($build[$region])) {
        foreach (Element::children($build[$region]) as $uuid) {
          $build[$region][$uuid]['#attributes']['class'][] = 'js-layout-builder-block';
          $build[$region][$uuid]['#attributes']['class'][] = 'layout-builder-block';
          $build[$region][$uuid]['#attributes']['data-layout-block-uuid'] = $uuid;
          $build[$region][$uuid]['#attributes']['data-layout-builder-highlight-id'] = $this
            ->blockUpdateHighlightId($uuid);
          $build[$region][$uuid]['#contextual_links'] = [
            'layout_builder_block' => [
              'route_parameters' => [
                'section_storage_type' => $storage_type,
                'section_storage' => $storage_id,
                'delta' => $delta,
                'region' => $region,
                'uuid' => $uuid,
              ],
              // Add metadata about the current operations available in
              // contextual links. This will invalidate the client-side cache of
              // links that were cached before the 'move' link was added.
              // @see layout_builder.links.contextual.yml
              'metadata' => [
                'operations' => 'move:update:remove',
              ],
            ],
          ];
        }
      }
      $build[$region]['layout_builder_add_block']['link'] = [
        '#type' => 'link',
        // Add one to the current delta since it is zero-indexed.
        '#title' => $this
          ->t('Add block <span class="visually-hidden">in @section, @region region</span>', [
          '@section' => $section_label,
          '@region' => $region_labels[$region],
        ]),
        '#url' => Url::fromRoute('layout_builder.choose_block', [
          'section_storage_type' => $storage_type,
          'section_storage' => $storage_id,
          'delta' => $delta,
          'region' => $region,
        ], [
          'attributes' => [
            'class' => [
              'use-ajax',
              'layout-builder__link',
              'layout-builder__link--add',
            ],
            'data-dialog-type' => 'dialog',
            'data-dialog-renderer' => 'off_canvas',
          ],
        ]),
      ];
      $build[$region]['layout_builder_add_block']['#type'] = 'container';
      $build[$region]['layout_builder_add_block']['#attributes'] = [
        'class' => [
          'layout-builder__add-block',
        ],
        'data-layout-builder-highlight-id' => $this
          ->blockAddHighlightId($delta, $region),
      ];
      $build[$region]['layout_builder_add_block']['#weight'] = 1000;
      $build[$region]['#attributes']['data-region'] = $region;
      $build[$region]['#attributes']['class'][] = 'layout-builder__region';
      $build[$region]['#attributes']['class'][] = 'js-layout-builder-region';
      $build[$region]['#attributes']['role'] = 'group';
      $build[$region]['#attributes']['aria-label'] = $this
        ->t('@region region in @section', [
        '@region' => $info['label'],
        '@section' => $section_label,
      ]);

      // Get weights of all children for use by the region label.
      $weights = array_map(function ($a) {
        return $a['#weight'] ?? 0;
      }, $build[$region]);

      // The region label is made visible when the move block dialog is open.
      $build[$region]['region_label'] = [
        '#type' => 'container',
        '#attributes' => [
          'class' => [
            'layout__region-info',
            'layout-builder__region-label',
          ],
          // A more detailed version of this information is already read by
          // screen readers, so this label can be hidden from them.
          'aria-hidden' => TRUE,
        ],
        '#markup' => $this
          ->t('Region: @region', [
          '@region' => $info['label'],
        ]),
        // Ensures the region label is displayed first.
        '#weight' => min($weights) - 1,
      ];
    }
    $build['#attributes']['data-layout-update-url'] = Url::fromRoute('layout_builder.move_block', [
      'section_storage_type' => $storage_type,
      'section_storage' => $storage_id,
    ])
      ->toString();
    $build['#attributes']['data-layout-delta'] = $delta;
    $build['#attributes']['class'][] = 'layout-builder__layout';
    $build['#attributes']['data-layout-builder-highlight-id'] = $this
      ->sectionUpdateHighlightId($delta);
    return [
      '#type' => 'container',
      '#attributes' => [
        'class' => [
          'layout-builder__section',
        ],
        'role' => 'group',
        'aria-label' => $section_label,
      ],
      'remove' => [
        '#type' => 'link',
        '#title' => $this
          ->t('Remove @section', [
          '@section' => $section_label,
        ]),
        '#url' => Url::fromRoute('layout_builder.remove_section', [
          'section_storage_type' => $storage_type,
          'section_storage' => $storage_id,
          'delta' => $delta,
        ]),
        '#attributes' => [
          'class' => [
            'use-ajax',
            'layout-builder__link',
            'layout-builder__link--remove',
          ],
          'data-dialog-type' => 'dialog',
          'data-dialog-renderer' => 'off_canvas',
        ],
      ],
      // The section label is added to sections without a "Configure section"
      // link, and is only visible when the move block dialog is open.
      'section_label' => [
        '#markup' => $this
          ->t('<span class="layout-builder__section-label" aria-hidden="true">@section</span>', [
          '@section' => $section_label,
        ]),
        '#access' => !$layout instanceof PluginFormInterface,
      ],
      'configure' => [
        '#type' => 'link',
        '#title' => $this
          ->t('Configure @section', [
          '@section' => $section_label,
        ]),
        '#access' => $layout instanceof PluginFormInterface,
        '#url' => Url::fromRoute('layout_builder.configure_section', [
          'section_storage_type' => $storage_type,
          'section_storage' => $storage_id,
          'delta' => $delta,
        ]),
        '#attributes' => [
          'class' => [
            'use-ajax',
            'layout-builder__link',
            'layout-builder__link--configure',
          ],
          'data-dialog-type' => 'dialog',
          'data-dialog-renderer' => 'off_canvas',
        ],
      ],
      'layout-builder__section' => $build,
    ];
  }

}