Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\book;
Chris@0: 
Chris@0: /**
Chris@0:  * Provides handling to render the book outline.
Chris@0:  */
Chris@0: class BookOutline {
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 new BookOutline.
Chris@0:    *
Chris@0:    * @param \Drupal\book\BookManagerInterface $book_manager
Chris@0:    *   The book manager.
Chris@0:    */
Chris@0:   public function __construct(BookManagerInterface $book_manager) {
Chris@0:     $this->bookManager = $book_manager;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Fetches the book link for the previous page of the book.
Chris@0:    *
Chris@0:    * @param array $book_link
Chris@0:    *   A fully loaded book link that is part of the book hierarchy.
Chris@0:    *
Chris@0:    * @return array
Chris@0:    *   A fully loaded book link for the page before the one represented in
Chris@0:    *   $book_link.
Chris@0:    */
Chris@0:   public function prevLink(array $book_link) {
Chris@0:     // If the parent is zero, we are at the start of a book.
Chris@0:     if ($book_link['pid'] == 0) {
Chris@0:       return NULL;
Chris@0:     }
Chris@0:     $flat = $this->bookManager->bookTreeGetFlat($book_link);
Chris@14:     reset($flat);
Chris@0:     $curr = NULL;
Chris@0:     do {
Chris@0:       $prev = $curr;
Chris@14:       $key = key($flat);
Chris@14:       $curr = current($flat);
Chris@14:       next($flat);
Chris@0:     } while ($key && $key != $book_link['nid']);
Chris@0: 
Chris@0:     if ($key == $book_link['nid']) {
Chris@0:       // The previous page in the book may be a child of the previous visible link.
Chris@0:       if ($prev['depth'] == $book_link['depth']) {
Chris@0:         // The subtree will have only one link at the top level - get its data.
Chris@0:         $tree = $this->bookManager->bookSubtreeData($prev);
Chris@0:         $data = array_shift($tree);
Chris@0:         // The link of interest is the last child - iterate to find the deepest one.
Chris@0:         while ($data['below']) {
Chris@0:           $data = end($data['below']);
Chris@0:         }
Chris@0:         $this->bookManager->bookLinkTranslate($data['link']);
Chris@0:         return $data['link'];
Chris@0:       }
Chris@0:       else {
Chris@0:         $this->bookManager->bookLinkTranslate($prev);
Chris@0:         return $prev;
Chris@0:       }
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Fetches the book link for the next page of the book.
Chris@0:    *
Chris@0:    * @param array $book_link
Chris@0:    *   A fully loaded book link that is part of the book hierarchy.
Chris@0:    *
Chris@0:    * @return array
Chris@0:    *   A fully loaded book link for the page after the one represented in
Chris@0:    *   $book_link.
Chris@0:    */
Chris@0:   public function nextLink(array $book_link) {
Chris@0:     $flat = $this->bookManager->bookTreeGetFlat($book_link);
Chris@14:     reset($flat);
Chris@0:     do {
Chris@14:       $key = key($flat);
Chris@14:       next($flat);
Chris@0:     } while ($key && $key != $book_link['nid']);
Chris@0: 
Chris@0:     if ($key == $book_link['nid']) {
Chris@0:       $next = current($flat);
Chris@0:       if ($next) {
Chris@0:         $this->bookManager->bookLinkTranslate($next);
Chris@0:       }
Chris@0:       return $next;
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Formats the book links for the child pages of the current page.
Chris@0:    *
Chris@0:    * @param array $book_link
Chris@0:    *   A fully loaded book link that is part of the book hierarchy.
Chris@0:    *
Chris@0:    * @return array
Chris@0:    *   HTML for the links to the child pages of the current page.
Chris@0:    */
Chris@0:   public function childrenLinks(array $book_link) {
Chris@0:     $flat = $this->bookManager->bookTreeGetFlat($book_link);
Chris@0: 
Chris@0:     $children = [];
Chris@0: 
Chris@0:     if ($book_link['has_children']) {
Chris@0:       // Walk through the array until we find the current page.
Chris@0:       do {
Chris@0:         $link = array_shift($flat);
Chris@0:       } while ($link && ($link['nid'] != $book_link['nid']));
Chris@0:       // Continue though the array and collect the links whose parent is this page.
Chris@0:       while (($link = array_shift($flat)) && $link['pid'] == $book_link['nid']) {
Chris@0:         $data['link'] = $link;
Chris@0:         $data['below'] = '';
Chris@0:         $children[] = $data;
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     if ($children) {
Chris@0:       return $this->bookManager->bookTreeOutput($children);
Chris@0:     }
Chris@0:     return '';
Chris@0:   }
Chris@0: 
Chris@0: }