WooCommerce -> Popularity custom sorting based on last 30days of sales

woocommerce-popularity-last-30-days.php

<?php

if (!wp_next_scheduled('set_last_month_product_sales_hook')) {
  wp_schedule_event(time(), 'daily', 'set_last_month_product_sales_hook');
}

add_action('set_last_month_product_sales_hook', 'cc_set_last_month_sales');
function cc_set_last_month_sales()
{

  $orders = wc_get_orders(
    array(
      'limit' => -1,
      'status' => array_map('wc_get_order_status_name', wc_get_is_paid_statuses()),
      'date_after' => date('Y-m-d', strtotime('-1 month')),
      'return' => 'ids',
    )
  );

  $identifiers = array();

  foreach ($orders as $order) {

    $items = wc_get_order($order)->get_items();
    foreach ($items as $item) {
      array_push($identifiers, $item->get_product_id());
    };
  };

  $counted_sales = array_count_values($identifiers);
  $keys = array();
  foreach ($counted_sales as $key => $val) {
    array_push($keys, $val);
    add_post_meta($key, 'wc_last_month_sales', $val);
  }
};

function cc_add_postmeta_ordering_args($sort_args)
{

  $orderby_value = isset($_GET['orderby']) ? wc_clean($_GET['orderby']) : apply_filters('woocommerce_default_catalog_orderby', get_option('woocommerce_default_catalog_orderby'));

  switch ($orderby_value) {
    case 'popularity':
      $sort_args['orderby']  = 'meta_value';
      $sort_args['order']    = 'asc';
      $sort_args['meta_key'] = 'wc_last_month_sales';
      break;
  }

  return $sort_args;
}
add_filter('woocommerce_get_catalog_ordering_args', 'cc_add_postmeta_ordering_args');

Hello!
It looks really good, but what about products that have not been ordered yet and therefore do not have meta_key = "wc_last_month_sales"?

@kosarlukascz This can be solved by adding a 0 value to all products before each run of the loop.

function handle_unordered_items()
{ 
  $products_ids = get_posts( array(
        'post_type'        => 'product',
        'numberposts'      => -1,
        'post_status'      => 'publish',
        'fields'           => 'ids',
        'meta_query'       => array( array(
            'key'     => 'wc_last_month_sales',
            'compare' => 'NOT EXISTS',
        ) )
    ) );

  foreach($product_ids as $product_id) {
    add_post_meta($product_id, 'wc_last_month_sales', 0);
  }
}

Dear mrkaluzny，
How can I apply these code？which file I need to update？

I add the code to theme functions.php is not work, how can I do? waiting for your reply, many thanks