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,
        ];
    }

}