LYNX-486: not_available_message and only_x_left_in_stock doesn't show the same available stock (#279)

Author: deepak-soni1

app/code/Magento/CatalogInventoryGraphQl/Model/Resolver/NotAvailableMessageResolver.php

@@ -49,7 +49,7 @@ public function resolve(Field $field, $context, ResolveInfo $info, array $value
         if ((int) $this->scopeConfig->getValue('cataloginventory/options/not_available_message') === 1) {
             return sprintf(
                 'Only %s available for sale. Please adjust the quantity to continue',
-                (string) $this->productStock->getProductAvailableStock($cartItem)
+                (string) $this->productStock->getProductSaleableQty($cartItem)
             );
         }
 

app/code/Magento/QuoteGraphQl/Model/CartItem/ProductStock.php

@@ -8,11 +8,15 @@
 namespace Magento\QuoteGraphQl\Model\CartItem;
 
 use Magento\Catalog\Api\Data\ProductInterface;
-use Magento\CatalogInventory\Model\StockState;
 use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\CatalogInventory\Api\StockConfigurationInterface;
+use Magento\CatalogInventory\Api\StockRegistryInterface;
+use Magento\CatalogInventory\Model\Configuration;
+use Magento\CatalogInventory\Model\StockState;
+use Magento\Framework\App\Config\ScopeConfigInterface;
 use Magento\Framework\Exception\NoSuchEntityException;
 use Magento\Quote\Model\Quote\Item;
-use Magento\CatalogInventory\Api\StockConfigurationInterface;
+use Magento\Store\Model\ScopeInterface;
 
 /**
  * Product Stock class to check availability of product
@@ -35,11 +39,15 @@ class ProductStock
      * @param ProductRepositoryInterface $productRepositoryInterface
      * @param StockState $stockState
      * @param StockConfigurationInterface $stockConfiguration
+     * @param ScopeConfigInterface $scopeConfig
+     * @param StockRegistryInterface $stockRegistry
      */
     public function __construct(
         private readonly ProductRepositoryInterface $productRepositoryInterface,
         private readonly StockState $stockState,
-        private readonly StockConfigurationInterface $stockConfiguration
+        private readonly StockConfigurationInterface $stockConfiguration,
+        private readonly ScopeConfigInterface $scopeConfig,
+        private readonly StockRegistryInterface $stockRegistry
     ) {
     }
 
@@ -74,6 +82,7 @@ public function isProductAvailable(Item $cartItem): bool
      * @param int $previousQty
      * @param int|float $requestedQty
      * @return bool
+     * @throws NoSuchEntityException
      */
     public function isStockAvailableBundle(Item $cartItem, int $previousQty, $requestedQty): bool
     {
@@ -188,4 +197,66 @@ private function getLowestStockValueOfBundleProduct(Item $cartItem): float
 
         return min($bundleStock);
     }
+
+    /**
+     * Returns the lowest stock value of bundle product
+     *
+     * @param Item $cartItem
+     * @param float $thresholdQty
+     * @return float
+     */
+    private function getLowestSaleableQtyOfBundleProduct(Item $cartItem, float $thresholdQty): float
+    {
+        $bundleStock = [];
+        foreach ($cartItem->getQtyOptions() as $qtyOption) {
+            $bundleStock[] = $this->getSaleableQty($qtyOption->getProduct(), $thresholdQty);
+        }
+        return $bundleStock ? (float)min($bundleStock) : 0.0;
+    }
+
+    /**
+     * Returns the cart item's saleable qty value
+     *
+     * @param Item $cartItem
+     * @return float
+     * @throws NoSuchEntityException
+     */
+    public function getProductSaleableQty(Item $cartItem): float
+    {
+        $thresholdQty = (float)$this->scopeConfig->getValue(
+            Configuration::XML_PATH_STOCK_THRESHOLD_QTY,
+            ScopeInterface::SCOPE_STORE
+        );
+
+        if ($thresholdQty === 0.0) {
+            return $this->getProductAvailableStock($cartItem);
+        }
+        
+        if ($cartItem->getProductType() === self::PRODUCT_TYPE_BUNDLE) {
+            return $this->getLowestSaleableQtyOfBundleProduct($cartItem, $thresholdQty);
+        }
+
+        $variantProduct = $this->getVariantProduct($cartItem);
+        if ($variantProduct !== null) {
+            return $this->getSaleableQty($variantProduct, $thresholdQty);
+        }
+
+        return $this->getSaleableQty($cartItem->getProduct(), $thresholdQty);
+    }
+
+    /**
+     * Get product saleable qty when "Catalog > Inventory > Stock Options > Only X left Threshold" is greater than 0
+     *
+     * @param ProductInterface $product
+     * @param float $thresholdQty
+     * @return float
+     */
+    private function getSaleableQty(ProductInterface $product, float $thresholdQty): float
+    {
+        $stockItem = $this->stockRegistry->getStockItem($product->getId());
+        $stockStatus = $this->stockRegistry->getStockStatus($product->getId(), $product->getStore()->getWebsiteId());
+        $stockCurrentQty = $stockStatus->getQty();
+        $stockLeft = $stockCurrentQty - $stockItem->getMinQty();
+        return ($stockCurrentQty >= 0 && $stockLeft <= $thresholdQty) ? (float)$stockCurrentQty : 0.0;
+    }
 }