LYNX-377: Configure the response to the shopper if the requested quantity is not available

Author: sumesh-GL

app/code/Magento/CatalogInventory/Model/Config/Source/NotAvailableMessage.php

@@ -0,0 +1,48 @@
+<?php
+/**
+ * Copyright 2024 Adobe
+ * All Rights Reserved.
+ */
+declare(strict_types=1);
+
+/**
+ * Catalog Inventory Config Backend Model
+ */
+namespace Magento\CatalogInventory\Model\Config\Source;
+
+use Magento\Framework\Data\OptionSourceInterface;
+
+class NotAvailableMessage implements OptionSourceInterface
+{
+    /**
+     * Options getter
+     *
+     * @return array
+     */
+    public function toOptionArray(): array
+    {
+        $options = [];
+        $options[] = [
+            'value' => 1,
+            'label' => __('Only X available for sale. Please adjust the quantity to continue'),
+        ];
+        $options[] = [
+            'value' => 2,
+            'label' => __('Not enough items for sale. Please adjust the quantity to continue'),
+        ];
+        return $options;
+    }
+
+    /**
+     * Get options in "key-value" format
+     *
+     * @return array
+     */
+    public function toArray(): array
+    {
+        return [
+            1 => __('Only X available for sale. Please adjust the quantity to continue'),
+            2 => __('Not enough items for sale. Please adjust the quantity to continue')
+        ];
+    }
+}

app/code/Magento/CatalogInventory/Model/StockStateProvider.php

@@ -9,6 +9,7 @@
 use Magento\Catalog\Model\ProductFactory;
 use Magento\CatalogInventory\Api\Data\StockItemInterface;
 use Magento\CatalogInventory\Model\Spi\StockStateProviderInterface;
+use Magento\Framework\App\Config\ScopeConfigInterface;
 use Magento\Framework\DataObject\Factory as ObjectFactory;
 use Magento\Framework\Locale\FormatInterface;
 use Magento\Framework\Math\Division as MathDivision;
@@ -48,13 +49,15 @@ class StockStateProvider implements StockStateProviderInterface
      * @param FormatInterface $localeFormat
      * @param ObjectFactory $objectFactory
      * @param ProductFactory $productFactory
+     * @param ScopeConfigInterface $scopeConfig
      * @param bool $qtyCheckApplicable
      */
     public function __construct(
         MathDivision $mathDivision,
         FormatInterface $localeFormat,
         ObjectFactory $objectFactory,
         ProductFactory $productFactory,
+        private readonly ScopeConfigInterface $scopeConfig,
         $qtyCheckApplicable = true
     ) {
         $this->mathDivision = $mathDivision;
@@ -165,9 +168,17 @@ public function checkQuoteItemQty(StockItemInterface $stockItem, $qty, $summaryQ
 
         if (!$this->checkQty($stockItem, $summaryQty) || !$this->checkQty($stockItem, $qty)) {
             $message = __('The requested qty is not available');
+            if ((int) $this->scopeConfig->getValue('cataloginventory/options/not_available_message') === 1) {
+                $itemMessage = (__(sprintf(
+                    'Only %s available for sale. Please adjust the quantity to continue',
+                    $stockItem->getQty() - $stockItem->getMinQty()
+                )));
+            } else {
+                $itemMessage = (__('Not enough items for sale. Please adjust the quantity to continue'));
+            }
             $result->setHasError(true)
                 ->setErrorCode('qty_available')
-                ->setMessage($message)
+                ->setMessage($itemMessage)
                 ->setQuoteMessage($message)
                 ->setQuoteMessageIndex('qty');
             return $result;

app/code/Magento/CatalogInventory/etc/adminhtml/system.xml

@@ -35,6 +35,10 @@
                     <label>Display Products Availability in Stock on Storefront</label>
                     <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
                 </field>
+                <field id="not_available_message" translate="label" type="select" sortOrder="5" showInDefault="1" showInWebsite="1" canRestore="1">
+                    <label>Not Available Message</label>
+                    <source_model>Magento\CatalogInventory\Model\Config\Source\NotAvailableMessage</source_model>
+                </field>
             </group>
             <group id="item_options" translate="label comment" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                 <comment>

app/code/Magento/CatalogInventory/etc/config.xml

@@ -14,6 +14,7 @@
                 <show_out_of_stock>0</show_out_of_stock>
                 <stock_threshold_qty>0</stock_threshold_qty>
                 <display_product_stock_status>1</display_product_stock_status>
+                <not_available_message>2</not_available_message>
             </options>
             <item_options>
                 <manage_stock>1</manage_stock>

app/code/Magento/CatalogInventory/i18n/en_US.csv

@@ -73,3 +73,6 @@ Stock,Stock
 "Done","Done"
 "The requested qty exceeds the maximum qty allowed in shopping cart","The requested qty exceeds the maximum qty allowed in shopping cart"
 "You cannot use decimal quantity for this product.","You cannot use decimal quantity for this product."
+"Not enough items for sale. Please adjust the quantity to continue","Not enough items for sale. Please adjust the quantity to continue"
+"Only X available for sale. Please adjust the quantity to continue","Only X available for sale. Please adjust the quantity to continue"
+"Only %s available for sale. Please adjust the quantity to continue","Only %s available for sale. Please adjust the quantity to continue"

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

@@ -0,0 +1,58 @@
+<?php
+/**
+ * Copyright 2024 Adobe
+ * All Rights Reserved.
+ */
+declare(strict_types=1);
+
+namespace Magento\CatalogInventoryGraphQl\Model\Resolver;
+
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\Exception\LocalizedException;
+use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
+use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Query\ResolverInterface;
+use Magento\Quote\Model\Quote\Item;
+use Magento\QuoteGraphQl\Model\CartItem\ProductStock;
+
+/**
+ * Resolver for not_available_message
+ * Returns the configured response to the shopper if the requested quantity is not available
+ */
+class NotAvailableMessageResolver implements ResolverInterface
+{
+    /**
+     * @param ScopeConfigInterface $scopeConfig
+     * @param ProductStock $productStock
+     */
+    public function __construct(
+        private readonly ScopeConfigInterface $scopeConfig,
+        private readonly ProductStock $productStock
+    ) {
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
+    {
+        if (!isset($value['model'])) {
+            throw new LocalizedException(__('"model" value should be specified'));
+        }
+        /** @var Item $cartItem */
+        $cartItem = $value['model'];
+
+        if ($this->productStock->isProductAvailable($cartItem)) {
+            return null;
+        }
+
+        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)
+            );
+        }
+
+        return 'Not enough items for sale. Please adjust the quantity to continue';
+    }
+}

app/code/Magento/CatalogInventoryGraphQl/composer.json

@@ -8,6 +8,8 @@
         "magento/module-store": "*",
         "magento/module-catalog": "*",
         "magento/module-catalog-inventory": "*",
+        "magento/module-quote": "*",
+        "magento/module-quote-graph-ql": "*",
         "magento/module-graph-ql": "*"
     },
     "license": [

app/code/Magento/CatalogInventoryGraphQl/etc/schema.graphqls

@@ -10,3 +10,7 @@ enum ProductStockStatus @doc(description: "States whether a product stock status
     IN_STOCK
     OUT_OF_STOCK
 }
+
+interface CartItemInterface @typeResolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\CartItemTypeResolver") @doc(description: "An interface for products in a cart.") {
+    not_available_message: String @doc(description: "Message to display when the product is not available with this selected option.") @resolver(class: "Magento\\CatalogInventoryGraphQl\\Model\\Resolver\\NotAvailableMessageResolver")
+}

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

@@ -52,25 +52,14 @@ public function __construct(
      */
     public function isProductAvailable(Item $cartItem): bool
     {
-        /**
-         * @var ProductInterface $variantProduct
-         * Configurable products cannot have stock, only its variants can. If the user adds a configurable product
-         * using its SKU and the selected options, we need to get the variant it refers to from the quote.
-         */
-        $variantProduct = null;
-
-        if ($cartItem->getProductType() === self::PRODUCT_TYPE_CONFIGURABLE) {
-            if ($cartItem->getChildren()[0] !== null) {
-                $variantProduct = $this->productRepositoryInterface->get($cartItem->getSku());
-            }
-        }
         $requestedQty = $cartItem->getQtyToAdd() ?? $cartItem->getQty();
         $previousQty = $cartItem->getPreviousQty() ?? 0;
 
         if ($cartItem->getProductType() === self::PRODUCT_TYPE_BUNDLE) {
             return $this->isStockAvailableBundle($cartItem, $previousQty, $requestedQty);
         }
 
+        $variantProduct = $this->getVariantProduct($cartItem);
         $requiredItemQty =  $requestedQty + $previousQty;
         if ($variantProduct !== null) {
             return $this->isStockQtyAvailable($variantProduct, $requestedQty, $requiredItemQty, $previousQty);
@@ -102,6 +91,50 @@ public function isStockAvailableBundle(Item $cartItem, int $previousQty, $reques
         return true;
     }
 
+    /**
+     * Returns the cart item's available stock value
+     *
+     * @param Item $cartItem
+     * @return float
+     * @throws NoSuchEntityException
+     */
+    public function getProductAvailableStock(Item $cartItem): float
+    {
+        if ($cartItem->getProductType() === self::PRODUCT_TYPE_BUNDLE) {
+            return $this->getLowestStockValueOfBundleProduct($cartItem);
+        }
+
+        $variantProduct = $this->getVariantProduct($cartItem);
+        if ($variantProduct !== null) {
+            return $this->getAvailableStock($variantProduct);
+        }
+        return $this->getAvailableStock($cartItem->getProduct());
+    }
+
+    /**
+     * Returns variant product if available
+     *
+     * @param Item $cartItem
+     * @return ProductInterface|null
+     * @throws NoSuchEntityException
+     */
+    private function getVariantProduct(Item $cartItem): ?ProductInterface
+    {
+        /**
+         * @var ProductInterface $variantProduct
+         * Configurable products cannot have stock, only its variants can. If the user adds a configurable product
+         * using its SKU and the selected options, we need to get the variant it refers to from the quote.
+         */
+        $variantProduct = null;
+
+        if ($cartItem->getProductType() === self::PRODUCT_TYPE_CONFIGURABLE) {
+            if ($cartItem->getChildren()[0] !== null) {
+                $variantProduct = $this->productRepositoryInterface->get($cartItem->getSku());
+            }
+        }
+        return $variantProduct;
+    }
+
     /**
      * Check if product is available in stock
      *
@@ -127,4 +160,32 @@ private function isStockQtyAvailable(
 
         return ((bool) $stockStatus->getHasError()) === false;
     }
+
+    /**
+     * Returns the product's available stock value
+     *
+     * @param ProductInterface $product
+     * @return float
+     */
+    private function getAvailableStock(ProductInterface $product): float
+    {
+        return $this->stockState->getStockQty($product->getId());
+    }
+
+    /**
+     * Returns the lowest stock value of bundle product
+     *
+     * @param Item $cartItem
+     * @return float
+     */
+    private function getLowestStockValueOfBundleProduct(Item $cartItem): float
+    {
+        $bundleStock = [];
+        $qtyOptions = $cartItem->getQtyOptions();
+        foreach ($qtyOptions as $qtyOption) {
+            $bundleStock[] = $this->getAvailableStock($qtyOption->getProduct());
+        }
+
+        return min($bundleStock);
+    }
 }