Create an on sale checker to make the plugin more user-friendly

Author: loevgaard

README.md

@@ -114,6 +114,40 @@ class YourFeedProcessor
 }
 ```
 
+## Check if a product is on sale
+If you want to check if a product is on sale, e.g. if you want to have a `Sale` category on your store, we have included
+a `\Setono\SyliusCatalogPromotionPlugin\Checker\OnSale\OnSaleCheckerInterface` service that checks exactly that:
+
+```php
+<?php
+
+use Setono\SyliusCatalogPromotionPlugin\Checker\OnSale\OnSaleCheckerInterface;
+use Setono\SyliusCatalogPromotionPlugin\Model\ProductInterface;
+
+class YourFeedProcessor
+{
+    public function __construct(private readonly OnSaleCheckerInterface $onSaleChecker) {
+    
+    }
+    
+    public function process(): void
+    {
+        /**
+         * A list of products you are processing
+         * 
+         * @var list<ProductInterface> $products 
+         */
+        $products = [];
+        
+        foreach ($products as $product) {
+            if($this->onSaleChecker->onSale($product)) {
+                // the product is on sale
+            }
+        }
+    }
+}
+```
+
 [ico-version]: https://poser.pugx.org/setono/sylius-catalog-promotion-plugin/v/stable
 [ico-unstable-version]: https://poser.pugx.org/setono/sylius-catalog-promotion-plugin/v/unstable
 [ico-license]: https://poser.pugx.org/setono/sylius-catalog-promotion-plugin/license

src/Checker/OnSale/OnSaleChecker.php

@@ -0,0 +1,63 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Setono\SyliusCatalogPromotionPlugin\Checker\OnSale;
+
+use Setono\SyliusCatalogPromotionPlugin\Applicator\RuntimePromotionsApplicatorInterface;
+use Setono\SyliusCatalogPromotionPlugin\Model\ProductInterface;
+use Sylius\Component\Channel\Context\ChannelContextInterface;
+use Sylius\Component\Core\Model\ChannelInterface;
+use Sylius\Component\Core\Model\ProductVariantInterface;
+use Webmozart\Assert\Assert;
+
+final class OnSaleChecker implements OnSaleCheckerInterface
+{
+    public function __construct(
+        private readonly ChannelContextInterface $channelContext,
+        private readonly RuntimePromotionsApplicatorInterface $runtimePromotionsApplicator,
+    ) {
+    }
+
+    public function onSale(ProductInterface|ProductVariantInterface $product, ChannelInterface $channel = null): bool
+    {
+        $channel = $channel ?? $this->channelContext->getChannel();
+        Assert::isInstanceOf($channel, ChannelInterface::class);
+
+        return match (true) {
+            $product instanceof ProductInterface => $this->checkProduct($product, $channel),
+            $product instanceof ProductVariantInterface => $this->checkVariant($product, $channel),
+        };
+    }
+
+    private function checkProduct(ProductInterface $product, ChannelInterface $channel): bool
+    {
+        /** @var ProductVariantInterface $variant */
+        foreach ($product->getEnabledVariants() as $variant) {
+            if ($this->checkVariant($variant, $channel)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private function checkVariant(ProductVariantInterface $variant, ChannelInterface $channel): bool
+    {
+        $channelPricing = $variant->getChannelPricingForChannel($channel);
+        if (null === $channelPricing) {
+            return false;
+        }
+
+        if ($channelPricing->isPriceReduced()) {
+            return true;
+        }
+
+        $product = $variant->getProduct();
+        Assert::isInstanceOf($product, ProductInterface::class);
+
+        $appliedPrice = $this->runtimePromotionsApplicator->apply($product, (int) $channelPricing->getPrice(), false);
+
+        return $appliedPrice < $channelPricing->getPrice();
+    }
+}

src/Checker/OnSale/OnSaleCheckerInterface.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Setono\SyliusCatalogPromotionPlugin\Checker\OnSale;
+
+use Setono\SyliusCatalogPromotionPlugin\Model\ProductInterface;
+use Sylius\Component\Core\Model\ChannelInterface;
+use Sylius\Component\Core\Model\ProductVariantInterface;
+
+interface OnSaleCheckerInterface
+{
+    /**
+     * @param ChannelInterface|null $channel if null the channel context will be used
+     */
+    public function onSale(ProductInterface|ProductVariantInterface $product, ChannelInterface $channel = null): bool;
+}

src/Resources/config/services/checker.xml

@@ -68,5 +68,14 @@
         <service id="Setono\SyliusCatalogPromotionPlugin\Checker\Runtime\EnabledRuntimeChecker">
             <tag name="setono_sylius_catalog_promotion.runtime_checker"/>
         </service>
+
+        <!-- On sale checker -->
+        <service id="Setono\SyliusCatalogPromotionPlugin\Checker\OnSale\OnSaleCheckerInterface"
+                 alias="Setono\SyliusCatalogPromotionPlugin\Checker\OnSale\OnSaleChecker"/>
+
+        <service id="Setono\SyliusCatalogPromotionPlugin\Checker\OnSale\OnSaleChecker">
+            <argument type="service" id="sylius.context.channel"/>
+            <argument type="service" id="Setono\SyliusCatalogPromotionPlugin\Applicator\RuntimePromotionsApplicatorInterface"/>
+        </service>
     </services>
 </container>