Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\book\Cache;
Chris@0: 
Chris@0: use Drupal\Core\Cache\CacheableMetadata;
Chris@0: use Drupal\Core\Cache\Context\CacheContextInterface;
Chris@0: use Symfony\Component\DependencyInjection\ContainerAwareInterface;
Chris@0: use Symfony\Component\DependencyInjection\ContainerAwareTrait;
Chris@0: use Symfony\Component\HttpFoundation\RequestStack;
Chris@0: 
Chris@0: /**
Chris@0:  * Defines the book navigation cache context service.
Chris@0:  *
Chris@0:  * Cache context ID: 'route.book_navigation'.
Chris@0:  *
Chris@0:  * This allows for book navigation location-aware caching. It depends on:
Chris@0:  * - whether the current route represents a book node at all
Chris@0:  * - and if so, where in the book hierarchy we are
Chris@0:  *
Chris@0:  * This class is container-aware to avoid initializing the 'book.manager'
Chris@0:  * service when it is not necessary.
Chris@0:  */
Chris@0: class BookNavigationCacheContext implements CacheContextInterface, ContainerAwareInterface {
Chris@0: 
Chris@0:   use ContainerAwareTrait;
Chris@0: 
Chris@0:   /**
Chris@0:    * The request stack.
Chris@0:    *
Chris@0:    * @var \Symfony\Component\HttpFoundation\RequestStack
Chris@0:    */
Chris@0:   protected $requestStack;
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a new BookNavigationCacheContext service.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
Chris@0:    *   The request stack.
Chris@0:    */
Chris@0:   public function __construct(RequestStack $request_stack) {
Chris@0:     $this->requestStack = $request_stack;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public static function getLabel() {
Chris@0:     return t("Book navigation");
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function getContext() {
Chris@0:     // Find the current book's ID.
Chris@0:     $current_bid = 0;
Chris@0:     if ($node = $this->requestStack->getCurrentRequest()->get('node')) {
Chris@0:       $current_bid = empty($node->book['bid']) ? 0 : $node->book['bid'];
Chris@0:     }
Chris@0: 
Chris@0:     // If we're not looking at a book node, then we're not navigating a book.
Chris@0:     if ($current_bid === 0) {
Chris@0:       return 'book.none';
Chris@0:     }
Chris@0: 
Chris@0:     // If we're looking at a book node, get the trail for that node.
Chris@0:     $active_trail = $this->container->get('book.manager')
Chris@0:       ->getActiveTrailIds($node->book['bid'], $node->book);
Chris@0:     return implode('|', $active_trail);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function getCacheableMetadata() {
Chris@0:     // The book active trail depends on the node and data attached to it.
Chris@0:     // That information is however not stored as part of the node.
Chris@0:     $cacheable_metadata = new CacheableMetadata();
Chris@0:     if ($node = $this->requestStack->getCurrentRequest()->get('node')) {
Chris@0:       // If the node is part of a book then we can use the cache tag for that
Chris@0:       // book. If not, then it can't be optimized away.
Chris@0:       if (!empty($node->book['bid'])) {
Chris@0:         $cacheable_metadata->addCacheTags(['bid:' . $node->book['bid']]);
Chris@0:       }
Chris@0:       else {
Chris@0:         $cacheable_metadata->setCacheMaxAge(0);
Chris@0:       }
Chris@0:     }
Chris@0:     return $cacheable_metadata;
Chris@0:   }
Chris@0: 
Chris@0: }