Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\block\Plugin\DisplayVariant;
Chris@0: 
Chris@0: use Drupal\block\BlockRepositoryInterface;
Chris@0: use Drupal\Core\Block\MainContentBlockPluginInterface;
Chris@0: use Drupal\Core\Block\TitleBlockPluginInterface;
Chris@0: use Drupal\Core\Block\MessagesBlockPluginInterface;
Chris@0: use Drupal\Core\Cache\CacheableMetadata;
Chris@0: use Drupal\Core\Display\PageVariantInterface;
Chris@0: use Drupal\Core\Entity\EntityViewBuilderInterface;
Chris@0: use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
Chris@0: use Drupal\Core\Display\VariantBase;
Chris@0: use Symfony\Component\DependencyInjection\ContainerInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Provides a page display variant that decorates the main content with blocks.
Chris@0:  *
Chris@0:  * To ensure essential information is displayed, each essential part of a page
Chris@0:  * has a corresponding block plugin interface, so that BlockPageVariant can
Chris@0:  * automatically provide a fallback in case no block for each of these
Chris@0:  * interfaces is placed.
Chris@0:  *
Chris@0:  * @see \Drupal\Core\Block\MainContentBlockPluginInterface
Chris@0:  * @see \Drupal\Core\Block\MessagesBlockPluginInterface
Chris@0:  *
Chris@0:  * @PageDisplayVariant(
Chris@0:  *   id = "block_page",
Chris@0:  *   admin_label = @Translation("Page with blocks")
Chris@0:  * )
Chris@0:  */
Chris@0: class BlockPageVariant extends VariantBase implements PageVariantInterface, ContainerFactoryPluginInterface {
Chris@0: 
Chris@0:   /**
Chris@0:    * The block repository.
Chris@0:    *
Chris@0:    * @var \Drupal\block\BlockRepositoryInterface
Chris@0:    */
Chris@0:   protected $blockRepository;
Chris@0: 
Chris@0:   /**
Chris@0:    * The block view builder.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Entity\EntityViewBuilderInterface
Chris@0:    */
Chris@0:   protected $blockViewBuilder;
Chris@0: 
Chris@0:   /**
Chris@0:    * The Block entity type list cache tags.
Chris@0:    *
Chris@0:    * @var string[]
Chris@0:    */
Chris@0:   protected $blockListCacheTags;
Chris@0: 
Chris@0:   /**
Chris@0:    * The render array representing the main page content.
Chris@0:    *
Chris@0:    * @var array
Chris@0:    */
Chris@0:   protected $mainContent = [];
Chris@0: 
Chris@0:   /**
Chris@0:    * The page title: a string (plain title) or a render array (formatted title).
Chris@0:    *
Chris@0:    * @var string|array
Chris@0:    */
Chris@0:   protected $title = '';
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a new BlockPageVariant.
Chris@0:    *
Chris@0:    * @param array $configuration
Chris@0:    *   A configuration array containing information about the plugin instance.
Chris@0:    * @param string $plugin_id
Chris@0:    *   The plugin ID for the plugin instance.
Chris@0:    * @param mixed $plugin_definition
Chris@0:    *   The plugin implementation definition.
Chris@0:    * @param \Drupal\block\BlockRepositoryInterface $block_repository
Chris@0:    *   The block repository.
Chris@0:    * @param \Drupal\Core\Entity\EntityViewBuilderInterface $block_view_builder
Chris@0:    *   The block view builder.
Chris@0:    * @param string[] $block_list_cache_tags
Chris@0:    *   The Block entity type list cache tags.
Chris@0:    */
Chris@0:   public function __construct(array $configuration, $plugin_id, $plugin_definition, BlockRepositoryInterface $block_repository, EntityViewBuilderInterface $block_view_builder, array $block_list_cache_tags) {
Chris@0:     parent::__construct($configuration, $plugin_id, $plugin_definition);
Chris@0:     $this->blockRepository = $block_repository;
Chris@0:     $this->blockViewBuilder = $block_view_builder;
Chris@0:     $this->blockListCacheTags = $block_list_cache_tags;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
Chris@0:     return new static(
Chris@0:       $configuration,
Chris@0:       $plugin_id,
Chris@0:       $plugin_definition,
Chris@0:       $container->get('block.repository'),
Chris@0:       $container->get('entity.manager')->getViewBuilder('block'),
Chris@0:       $container->get('entity.manager')->getDefinition('block')->getListCacheTags()
Chris@0:     );
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function setMainContent(array $main_content) {
Chris@0:     $this->mainContent = $main_content;
Chris@0:     return $this;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function setTitle($title) {
Chris@0:     $this->title = $title;
Chris@0:     return $this;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function build() {
Chris@0:     // Track whether blocks showing the main content and messages are displayed.
Chris@0:     $main_content_block_displayed = FALSE;
Chris@0:     $messages_block_displayed = FALSE;
Chris@0: 
Chris@0:     $build = [
Chris@0:       '#cache' => [
Chris@0:         'tags' => $this->blockListCacheTags,
Chris@0:       ],
Chris@0:     ];
Chris@0:     // Load all region content assigned via blocks.
Chris@0:     $cacheable_metadata_list = [];
Chris@0:     foreach ($this->blockRepository->getVisibleBlocksPerRegion($cacheable_metadata_list) as $region => $blocks) {
Chris@0:       /** @var $blocks \Drupal\block\BlockInterface[] */
Chris@0:       foreach ($blocks as $key => $block) {
Chris@0:         $block_plugin = $block->getPlugin();
Chris@0:         if ($block_plugin instanceof MainContentBlockPluginInterface) {
Chris@0:           $block_plugin->setMainContent($this->mainContent);
Chris@0:           $main_content_block_displayed = TRUE;
Chris@0:         }
Chris@0:         elseif ($block_plugin instanceof TitleBlockPluginInterface) {
Chris@0:           $block_plugin->setTitle($this->title);
Chris@0:         }
Chris@0:         elseif ($block_plugin instanceof MessagesBlockPluginInterface) {
Chris@0:           $messages_block_displayed = TRUE;
Chris@0:         }
Chris@0:         $build[$region][$key] = $this->blockViewBuilder->view($block);
Chris@0: 
Chris@0:         // The main content block cannot be cached: it is a placeholder for the
Chris@0:         // render array returned by the controller. It should be rendered as-is,
Chris@0:         // with other placed blocks "decorating" it. Analogous reasoning for the
Chris@0:         // title block.
Chris@0:         if ($block_plugin instanceof MainContentBlockPluginInterface || $block_plugin instanceof TitleBlockPluginInterface) {
Chris@0:           unset($build[$region][$key]['#cache']['keys']);
Chris@0:         }
Chris@0:       }
Chris@0:       if (!empty($build[$region])) {
Chris@0:         // \Drupal\block\BlockRepositoryInterface::getVisibleBlocksPerRegion()
Chris@0:         // returns the blocks in sorted order.
Chris@0:         $build[$region]['#sorted'] = TRUE;
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     // If no block that shows the main content is displayed, still show the main
Chris@0:     // content. Otherwise the end user will see all displayed blocks, but not
Chris@0:     // the main content they came for.
Chris@0:     if (!$main_content_block_displayed) {
Chris@0:       $build['content']['system_main'] = $this->mainContent;
Chris@0:     }
Chris@0: 
Chris@0:     // If no block displays status messages, still render them.
Chris@0:     if (!$messages_block_displayed) {
Chris@0:       $build['content']['messages'] = [
Chris@0:         '#weight' => -1000,
Chris@0:         '#type' => 'status_messages',
Chris@0:       ];
Chris@0:     }
Chris@0: 
Chris@0:     // If any render arrays are manually placed, render arrays and blocks must
Chris@0:     // be sorted.
Chris@0:     if (!$main_content_block_displayed || !$messages_block_displayed) {
Chris@0:       unset($build['content']['#sorted']);
Chris@0:     }
Chris@0: 
Chris@0:     // The access results' cacheability is currently added to the top level of the
Chris@0:     // render array. This is done to prevent issues with empty regions being
Chris@0:     // displayed.
Chris@0:     // This would need to be changed to allow caching of block regions, as each
Chris@0:     // region must then have the relevant cacheable metadata.
Chris@0:     $merged_cacheable_metadata = CacheableMetadata::createFromRenderArray($build);
Chris@0:     foreach ($cacheable_metadata_list as $cacheable_metadata) {
Chris@0:       $merged_cacheable_metadata = $merged_cacheable_metadata->merge($cacheable_metadata);
Chris@0:     }
Chris@0:     $merged_cacheable_metadata->applyTo($build);
Chris@0: 
Chris@0:     return $build;
Chris@0:   }
Chris@0: 
Chris@0: }