WooCommerce Stock Report

I want to have a report page with all elements currently in stock, a realtime stock status.

This is the code I found and customize

<?php
/*
Template Name: Stock Report :)
*/
if (!is_user_logged_in() || !current_user_can('manage_options')) wp_die('This page is private.');
?>
<!DOCTYPE HTML>
<html>

<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <title><?php _e('Stock Report'); ?></title>
    <style>
        body {
            background: white;
            color: black;
            width: 95%;
            margin: 0 auto;
        }

        table {
            border: 1px solid #000;
            width: 100%;
        }

        table td,
        table th {
            border: 1px solid #000;
            padding: 6px;
        }
    </style>
</head>

<body>
    <header>
        <?php if (have_posts()) : while (have_posts()) : the_post(); ?>

                <h1 class="title"><?php the_title(); ?></h1>

                <?php the_content(); ?>

        <?php endwhile;
        endif; ?>
    </header>
    <section>
        <?php

        global $woocommerce;
        ?>
        <table cellspacing="0" cellpadding="2">
            <thead>
                <tr>
                    <th scope="col" style="text-align:left;"><?php _e('Product', 'woothemes'); ?></th>
                    <th scope="col" style="text-align:left;"><?php _e('COD', 'woothemes'); ?></th>
                    <th scope="col" style="text-align:left;"><?php _e('Scorta', 'woothemes'); ?></th>
                </tr>
            </thead>
            <tbody>
                <?php

                $args = array(
                    'post_type'            => 'product',
                    'post_status'         => 'publish',
                    'posts_per_page'     => -1,
                    'orderby'            => 'title',
                    'order'                => 'ASC',




                );

                $loop = new WP_Query($args);

                while ($loop->have_posts()) : $loop->the_post();

                    global $product;
                    if ($product->stock > 0) {
                ?>
                        <tr>
                            <td><?php echo $product->get_title(); ?></td>
                            <td><?php echo $product->sku; ?></td>
                            <td><?php echo $product->stock; ?></td>
                            <td><?php echo $product->get_image('thumbnail'); ?></td>

                        </tr>
                <?php
                    }
                endwhile;

                ?>
            </tbody>
        </table>

        <h2>Variations</h2>
        <table cellspacing="0" cellpadding="2">
            <thead>
                <tr>
                    <th scope="col" style="text-align:left;"><?php _e('Variation', 'woothemes'); ?></th>
                    <th scope="col" style="text-align:left;"><?php _e('Parent', 'woothemes'); ?></th>
                    <th scope="col" style="text-align:left;"><?php _e('SKU', 'woothemes'); ?></th>
                    <th scope="col" style="text-align:left;"><?php _e('Stock', 'woothemes'); ?></th>
                </tr>
            </thead>
            <tbody>
                <?php

                $args = array(
                    'post_type'            => 'product_variation',
                    'post_status'         => 'publish',
                    'posts_per_page'     => -1,
                    'orderby'            => 'title',
                    'order'                => 'ASC',
                    'meta_query' => array(
                        array(
                            'key'         => '_stock',
                            'value'     => array('', false, null),
                            'compare'     => 'NOT IN'
                        )
                    )
                );

                $loop = new WP_Query($args);

                while ($loop->have_posts()) : $loop->the_post();

                    $product = new WC_Product_Variation($loop->post->ID);
                    $variation = wc_get_product($product);
                    $variation->get_formatted_name();
                    if ($product->stock > 0) {

                ?>
                        <tr>
                            <td><?php echo $product->get_title(); ?></td>
                            <td><?php echo get_the_title($loop->post->post_parent); ?></td>
                            <td><?php echo $product->sku; ?></td>
                            <td><?php echo $product->stock; ?></td>
                            <td><?php echo $product->get_image('thumbnail'); ?></td>
                        </tr>
                <?php
                    }
                endwhile;

                ?>
            </tbody>
        </table>
</body>

</html>

the first loop has the simple product, the second loop the variable product.
Can you help me to have an unique loop?

So how can I group the variable product and have the total stock?
thanks