Virtuemart Details Page in product.php sublayout

<div class="vm-details-button">
                <?php // Product Details Button
                $link = empty($product->link)? $product->canonical:$product->link;
                echo JHtml::link($link.$ItemidStr,vmText::_ ( 'COM_VIRTUEMART_PRODUCT_DETAILS' ), array ('title' => $product->product_name, 'class' => 'product-details fa fa-plus' ) );
                //echo JHtml::link ( JRoute::_ ( 'index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=' . $product->virtuemart_product_id . '&virtuemart_category_id=' . $product->virtuemart_category_id , FALSE), vmText::_ ( 'COM_VIRTUEMART_PRODUCT_DETAILS' ), array ('title' => $product->product_name, 'class' => 'product-details' ) );
                ?>
            </div>