Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\book;
Chris@0: 
Chris@18: use Drupal\Core\Entity\EntityTypeManagerInterface;
Chris@0: use Drupal\node\NodeInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Provides methods for exporting book to different formats.
Chris@0:  *
Chris@0:  * If you would like to add another format, swap this class in container.
Chris@0:  */
Chris@0: class BookExport {
Chris@0: 
Chris@0:   /**
Chris@0:    * The node storage.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Entity\EntityStorageInterface
Chris@0:    */
Chris@0:   protected $nodeStorage;
Chris@0: 
Chris@0:   /**
Chris@0:    * The node view builder.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Entity\EntityViewBuilderInterface
Chris@0:    */
Chris@0:   protected $viewBuilder;
Chris@0: 
Chris@0:   /**
Chris@0:    * The book manager.
Chris@0:    *
Chris@0:    * @var \Drupal\book\BookManagerInterface
Chris@0:    */
Chris@0:   protected $bookManager;
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a BookExport object.
Chris@0:    *
Chris@18:    * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
Chris@18:    *   The entity type manager.
Chris@0:    * @param \Drupal\book\BookManagerInterface $book_manager
Chris@0:    *   The book manager.
Chris@0:    */
Chris@18:   public function __construct(EntityTypeManagerInterface $entity_type_manager, BookManagerInterface $book_manager) {
Chris@18:     $this->nodeStorage = $entity_type_manager->getStorage('node');
Chris@18:     $this->viewBuilder = $entity_type_manager->getViewBuilder('node');
Chris@0:     $this->bookManager = $book_manager;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Generates HTML for export when invoked by book_export().
Chris@0:    *
Chris@0:    * The given node is embedded to its absolute depth in a top level section. For
Chris@0:    * example, a child node with depth 2 in the hierarchy is contained in
Chris@0:    * (otherwise empty) <div> elements corresponding to depth 0 and depth 1.
Chris@0:    * This is intended to support WYSIWYG output; for instance, level 3 sections
Chris@0:    * always look like level 3 sections, no matter their depth relative to the
Chris@0:    * node selected to be exported as printer-friendly HTML.
Chris@0:    *
Chris@0:    * @param \Drupal\node\NodeInterface $node
Chris@0:    *   The node to export.
Chris@0:    *
Chris@0:    * @return array
Chris@0:    *   A render array representing the HTML for a node and its children in the
Chris@0:    *   book hierarchy.
Chris@0:    *
Chris@0:    * @throws \Exception
Chris@0:    *   Thrown when the node was not attached to a book.
Chris@0:    */
Chris@0:   public function bookExportHtml(NodeInterface $node) {
Chris@0:     if (!isset($node->book)) {
Chris@0:       throw new \Exception();
Chris@0:     }
Chris@0: 
Chris@0:     $tree = $this->bookManager->bookSubtreeData($node->book);
Chris@0:     $contents = $this->exportTraverse($tree, [$this, 'bookNodeExport']);
Chris@0:     return [
Chris@0:       '#theme' => 'book_export_html',
Chris@0:       '#title' => $node->label(),
Chris@0:       '#contents' => $contents,
Chris@0:       '#depth' => $node->book['depth'],
Chris@0:       '#cache' => [
Chris@0:         'tags' => $node->getEntityType()->getListCacheTags(),
Chris@0:       ],
Chris@0:     ];
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Traverses the book tree to build printable or exportable output.
Chris@0:    *
Chris@0:    * During the traversal, the callback is applied to each node and is called
Chris@0:    * recursively for each child of the node (in weight, title order).
Chris@0:    *
Chris@0:    * @param array $tree
Chris@0:    *   A subtree of the book menu hierarchy, rooted at the current page.
Chris@0:    * @param callable $callable
Chris@0:    *   A callback to be called upon visiting a node in the tree.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    *   The output generated in visiting each node.
Chris@0:    */
Chris@0:   protected function exportTraverse(array $tree, $callable) {
Chris@0:     // If there is no valid callable, use the default callback.
Chris@0:     $callable = !empty($callable) ? $callable : [$this, 'bookNodeExport'];
Chris@0: 
Chris@0:     $build = [];
Chris@0:     foreach ($tree as $data) {
Chris@0:       // Note- access checking is already performed when building the tree.
Chris@0:       if ($node = $this->nodeStorage->load($data['link']['nid'])) {
Chris@0:         $children = $data['below'] ? $this->exportTraverse($data['below'], $callable) : '';
Chris@0:         $build[] = call_user_func($callable, $node, $children);
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     return $build;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Generates printer-friendly HTML for a node.
Chris@0:    *
Chris@0:    * @param \Drupal\node\NodeInterface $node
Chris@0:    *   The node that will be output.
Chris@0:    * @param string $children
Chris@0:    *   (optional) All the rendered child nodes within the current node. Defaults
Chris@0:    *   to an empty string.
Chris@0:    *
Chris@0:    * @return array
Chris@0:    *   A render array for the exported HTML of a given node.
Chris@0:    *
Chris@0:    * @see \Drupal\book\BookExport::exportTraverse()
Chris@0:    */
Chris@0:   protected function bookNodeExport(NodeInterface $node, $children = '') {
Chris@0:     $build = $this->viewBuilder->view($node, 'print', NULL);
Chris@0:     unset($build['#theme']);
Chris@0: 
Chris@0:     return [
Chris@0:       '#theme' => 'book_node_export_html',
Chris@0:       '#content' => $build,
Chris@0:       '#node' => $node,
Chris@0:       '#children' => $children,
Chris@0:     ];
Chris@0:   }
Chris@0: 
Chris@0: }