70 lines
2.0 KiB
PHP
70 lines
2.0 KiB
PHP
<?php namespace BookStack\Entities\Tools;
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use BookStack\Entities\Models\BookChild;
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use BookStack\Entities\Models\Entity;
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use Illuminate\Support\Collection;
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/**
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* Finds the next or previous content of a book element (page or chapter).
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*/
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class NextPreviousContentLocator
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{
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protected $relativeBookItem;
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protected $flatTree;
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protected $currentIndex = null;
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/**
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* NextPreviousContentLocator constructor.
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*/
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public function __construct(BookChild $relativeBookItem, Collection $bookTree)
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{
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$this->relativeBookItem = $relativeBookItem;
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$this->flatTree = $this->treeToFlatOrderedCollection($bookTree);
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$this->currentIndex = $this->getCurrentIndex();
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}
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/**
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* Get the next logical entity within the book hierarchy.
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*/
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public function getNext(): ?Entity
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{
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return $this->flatTree->get($this->currentIndex + 1);
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}
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/**
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* Get the next logical entity within the book hierarchy.
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*/
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public function getPrevious(): ?Entity
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{
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return $this->flatTree->get($this->currentIndex - 1);
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}
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/**
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* Get the index of the current relative item.
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*/
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protected function getCurrentIndex(): ?int
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{
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$index = $this->flatTree->search(function (Entity $entity) {
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return get_class($entity) === get_class($this->relativeBookItem)
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&& $entity->id === $this->relativeBookItem->id;
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});
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return $index === false ? null : $index;
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}
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/**
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* Convert a book tree collection to a flattened version
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* where all items follow the expected order of user flow.
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*/
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protected function treeToFlatOrderedCollection(Collection $bookTree): Collection
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{
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$flatOrdered = collect();
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/** @var Entity $item */
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foreach ($bookTree->all() as $item) {
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$flatOrdered->push($item);
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$childPages = $item->visible_pages ?? [];
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$flatOrdered = $flatOrdered->concat($childPages);
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}
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return $flatOrdered;
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}
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}
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