MAGE-791 Add alt registry for current category

Observer/RegisterCurrentCategoryObserver.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Algolia\AlgoliaSearch\Observer;
+
+use Algolia\AlgoliaSearch\Registry\CurrentCategory;
+use Magento\Catalog\Api\Data\CategoryInterface;
+use Magento\Framework\Event\Observer;
+use Magento\Framework\Event\ObserverInterface;
+
+class RegisterCurrentCategoryObserver implements ObserverInterface
+{
+    /** @var CurrentCategory  */
+    private CurrentCategory $currentCategory;
+
+    public function __construct(CurrentCategory $currentCategory) {
+        $this->currentCategory = $currentCategory;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function execute(Observer $observer)
+    {
+        /** @var CategoryInterface */
+        $category = $observer->getEvent()->getData('category');
+        $this->currentCategory->set($category);
+    }
+}

Registry/CurrentCategory.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Algolia\AlgoliaSearch\Registry;
+
+use Magento\Catalog\Api\CategoryRepositoryInterface;
+use Magento\Catalog\Api\Data\CategoryInterface;
+use Magento\Catalog\Api\Data\CategoryInterfaceFactory;
+
+class CurrentCategory
+{
+    private CategoryInterface $category;
+    private CategoryRepositoryInterface $categoryRepository;
+    private CategoryInterfaceFactory $categoryFactory;
+
+    public function __construct(
+        CategoryRepositoryInterface $categoryRepository,
+        CategoryInterfaceFactory $categoryFactory
+    )
+    {
+        $this->categoryRepository = $categoryRepository;
+        $this->categoryFactory = $categoryFactory;
+    }
+
+    public function set(CategoryInterface $category): void {
+        $this->category = $category;
+    }
+
+    public function get(): CategoryInterface {
+        return $this->category ?? $this->categoryFactory->create();
+    }
+}

etc/frontend/events.xml

@@ -23,4 +23,9 @@
     <event name="checkout_onepage_controller_success_action">
         <observer name="algoliasearch_insights_place_order_event" instance="Algolia\AlgoliaSearch\Observer\Insights\CheckoutOnepageControllerSuccessAction" />
     </event>
+
+    <!-- Registry -->
+    <event name="catalog_controller_category_init_after">
+        <observer name="algoliasearch_current_category" instance="Algolia\AlgoliaSearch\Observer\RegisterCurrentCategoryObserver"/>
+    </event>
 </config>