add method checking if stock needed is valid or not

core/lib/Thelia/Model/Product.php

@@ -3,7 +3,38 @@
 namespace Thelia\Model;
 
 use Thelia\Model\Base\Product as BaseProduct;
+use Thelia\Model\Base\StockQuery;
 
 class Product extends BaseProduct {
 
+    public function stockIsValid($value, $combination = null)
+    {
+        $isValid = true;
+
+        if (ConfigQuery::read("verifyStock", 1) == 1) {
+
+            $stock = StockQuery::create()
+                ->filterByProduct($this);
+
+            if ($combination) {
+                $stock->filterByCombinationId($combination);
+            }
+
+            $stock = $stock->findOne();
+
+            if ($stock) {
+
+                if($stock->getQuantity() < $value) {
+                    $isValid = false;
+                }
+
+            } else {
+                $isValid = false;
+            }
+
+        }
+
+        return $isValid;
+    }
+
 }