Add variation products programmatically on Woo

woo_update.php

//The array has this format

//[
//     {
//         "name"        : "T-Shirt",
//         "available_attributes": [
//             "size", "color"
//         ],
//         "variations":
//         [
//             {
//                 "attributes": {
//                     "size"  : "Small",
//                     "color" : "Red"
//                 },
//                 "price" : "8.00",
//                 "sku"         : "TS1000"
//             },
//             {
//                 "attributes": {
//                     "size"  : "Medium",
//                     "color" : "Red"
//                 },
//                 "price" : "10.00",
//                 "sku"         : "TS1000"
//             },
//             {
//                 "attributes": {
//                     "size"  : "Small",
//                     "color" : "Blue"
//                 },
//                 "price" : "8.00",
//                 "sku"         : "TS1000"
//             },
//             {
//                 "attributes": {
//                     "size"  : "Large",
//                     "color" : "Blue"
//                 },
//                 "price" : "12.00",
//                 "sku"         : "TS1000"
//             }                           
//         ]
//     },...
//]


function insert_product ($product_data) {
    $post = array( // Set up the basic post data to insert for our product

        'post_author'  => 1,
        'post_content' => '',
        'post_status'  => 'pending',
        'post_title'   => $product_data['name'],
        'post_parent'  => '',
        'post_type'    => 'product'
    );

    $post_id = wp_insert_post($post); // Insert the post returning the new post id

    if (!$post_id) // If there is no post id something has gone wrong so don't proceed
    {
        return false;
    }

    //update_post_meta($post_id, '_sku', $product_data['sku']); // Set its SKU
    update_post_meta( $post_id,'_visibility','visible'); // Set the product to visible, if not it won't show on the front end

    //wp_set_object_terms($post_id, $product_data['categories'], 'product_cat'); // Set up its categories
    wp_set_object_terms($post_id, 'variable', 'product_type'); // Set it to a variable product type

    insert_product_attributes($post_id, $product_data['available_attributes'], $product_data['variations']); // Add attributes passing the new post id, attributes & variations
    insert_product_variations($post_id, $product_data['variations']); // Insert variations passing the new post id & variations   
}

function insert_product_attributes ($post_id, $available_attributes, $variations) {
    foreach ($available_attributes as $attribute) // Go through each attribute
    {   
        $values = array(); // Set up an array to store the current attributes values.
        foreach ($variations as $variation) // Loop each variation in the file
        {
            $attribute_keys = array_keys($variation['attributes']); // Get the keys for the current variations attributes
            foreach ($attribute_keys as $key) // Loop through each key
            {
                if ($key === $attribute) // If this attributes key is the top level attribute add the value to the $values array
                {
                    $values[] = $variation['attributes'][$key];
                }
            }
        }
        // Essentially we want to end up with something like this for each attribute:
        // $values would contain: array('small', 'medium', 'medium', 'large');
        $values = array_unique($values); // Filter out duplicate values
        // Store the values to the attribute on the new post, for example without variables:
        // wp_set_object_terms(23, array('small', 'medium', 'large'), 'pa_size');
        wp_set_object_terms($post_id, $values, 'pa_' . $attribute);
    }
    $product_attributes_data = array(); // Setup array to hold our product attributes data
    foreach ($available_attributes as $attribute) // Loop round each attribute
    {
        $product_attributes_data['pa_'.$attribute] = array( // Set this attributes array to a key to using the prefix 'pa'

            'name'         => 'pa_'.$attribute,
            'value'        => '',
            'is_visible'   => '1',
            'is_variation' => '1',
            'is_taxonomy'  => '1'

        );
    }
    update_post_meta($post_id, '_product_attributes', $product_attributes_data); // Attach the above array to the new posts meta data key '_product_attributes'
}

function insert_product_variations ($post_id, $variations) {
    foreach ($variations as $index => $variation)
    {
        $variation_post = array( // Setup the post data for the variation

            'post_title'  => 'Variation #'.$index.' of '.count($variations).' for product#'. $post_id,
            'post_name'   => 'product-'.$post_id.'-variation-'.$index,
            'post_status' => 'publish',
            'post_parent' => $post_id,
            'post_type'   => 'product_variation',
            'guid'        => home_url() . '/?product_variation=product-' . $post_id . '-variation-' . $index
        );
        $variation_post_id = wp_insert_post($variation_post); // Insert the variation
        foreach ($variation['attributes'] as $attribute => $value) // Loop through the variations attributes
        {   
            $attribute_term = get_term_by('name', $value, 'pa_'.$attribute); // We need to insert the slug not the name into the variation post meta
            update_post_meta($variation_post_id, 'attribute_pa_'.$attribute, $attribute_term->slug);
          // Again without variables: update_post_meta(25, 'attribute_pa_size', 'small')
        }
        update_post_meta($variation_post_id, '_price', $variation['price']);
		update_post_meta($variation_post_id, '_regular_price', $variation['price']);
		update_post_meta($variation_post_id, '_sku', $variation['sku']);
    }
}

function insert_products($products) {
    if (!empty($products)) // No point proceeding if there are no products
    {
        array_map('insert_product', $products); // Run 'insert_product' function from above for each product
    }
}