BookStack Code Mirror - bookstack/blob - app/Entities/Tools/NextPreviousContentLocator.php

   1 <?php
   2
   3 namespace BookStack\Entities\Tools;
   4
   5 use BookStack\Entities\Models\BookChild;
   6 use BookStack\Entities\Models\Entity;
   7 use Illuminate\Support\Collection;
   8
   9 /**
  10  * Finds the next or previous content of a book element (page or chapter).
  11  */
  12 class NextPreviousContentLocator
  13 {
  14     protected $relativeBookItem;
  15     protected $flatTree;
  16     protected $currentIndex = null;
  17
  18     /**
  19      * NextPreviousContentLocator constructor.
  20      */
  21     public function __construct(BookChild $relativeBookItem, Collection $bookTree)
  22     {
  23         $this->relativeBookItem = $relativeBookItem;
  24         $this->flatTree = $this->treeToFlatOrderedCollection($bookTree);
  25         $this->currentIndex = $this->getCurrentIndex();
  26     }
  27
  28     /**
  29      * Get the next logical entity within the book hierarchy.
  30      */
  31     public function getNext(): ?Entity
  32     {
  33         return $this->flatTree->get($this->currentIndex + 1);
  34     }
  35
  36     /**
  37      * Get the next logical entity within the book hierarchy.
  38      */
  39     public function getPrevious(): ?Entity
  40     {
  41         return $this->flatTree->get($this->currentIndex - 1);
  42     }
  43
  44     /**
  45      * Get the index of the current relative item.
  46      */
  47     protected function getCurrentIndex(): ?int
  48     {
  49         $index = $this->flatTree->search(function (Entity $entity) {
  50             return get_class($entity) === get_class($this->relativeBookItem)
  51                 && $entity->id === $this->relativeBookItem->id;
  52         });
  53
  54         return $index === false ? null : $index;
  55     }
  56
  57     /**
  58      * Convert a book tree collection to a flattened version
  59      * where all items follow the expected order of user flow.
  60      */
  61     protected function treeToFlatOrderedCollection(Collection $bookTree): Collection
  62     {
  63         $flatOrdered = collect();
  64         /** @var Entity $item */
  65         foreach ($bookTree->all() as $item) {
  66             $flatOrdered->push($item);
  67             $childPages = $item->getAttribute('visible_pages') ?? [];
  68             $flatOrdered = $flatOrdered->concat($childPages);
  69         }
  70
  71         return $flatOrdered;
  72     }
  73 }