public static function save_variations( $post_id, $post ) {
    // phpcs:disable WordPress.Security.NonceVerification.Missing
    if ( isset( $_POST['variable_post_id'] ) ) {
      $parent = wc_get_product( $post_id );
      $parent->set_default_attributes( self::prepare_set_attributes( $parent->get_attributes(), 'default_attribute_' ) );
      $parent->save();

      $max_loop   = max( array_keys( wp_unslash( $_POST['variable_post_id'] ) ) ); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
      $data_store = $parent->get_data_store();
      $data_store->sort_all_product_variations( $parent->get_id() );

      for ( $i = 0; $i <= $max_loop; $i++ ) {

        if ( ! isset( $_POST['variable_post_id'][ $i ] ) ) {
          continue;
        }
        $variation_id = absint( $_POST['variable_post_id'][ $i ] );
        $variation    = wc_get_product_object( 'variation', $variation_id );
        $stock        = null;

        // Handle stock changes.
        if ( isset( $_POST['variable_stock'], $_POST['variable_stock'][ $i ] ) ) {
          if ( isset( $_POST['variable_original_stock'], $_POST['variable_original_stock'][ $i ] ) && wc_stock_amount( $variation->get_stock_quantity( 'edit' ) ) !== wc_stock_amount( wp_unslash( $_POST['variable_original_stock'][ $i ] ) ) ) {
            /* translators: 1: product ID 2: quantity in stock */
            WC_Admin_Meta_Boxes::add_error( sprintf( __( 'The stock has not been updated because the value has changed since editing. Product %1$d has %2$d units in stock.', 'woocommerce' ), $variation->get_id(), $variation->get_stock_quantity( 'edit' ) ) );
          } else {
            $stock = wc_stock_amount( wp_unslash( $_POST['variable_stock'][ $i ] ) );
          }
        }

        // Handle dates.
        $date_on_sale_from = '';
        $date_on_sale_to   = '';

        // Force date from to beginning of day.
        if ( isset( $_POST['variable_sale_price_dates_from'][ $i ] ) ) {
          $date_on_sale_from = wc_clean( wp_unslash( $_POST['variable_sale_price_dates_from'][ $i ] ) );

          if ( ! empty( $date_on_sale_from ) ) {
            $date_on_sale_from = date( 'Y-m-d 00:00:00', strtotime( $date_on_sale_from ) );
          }
        }

        // Force date to to the end of the day.
        if ( isset( $_POST['variable_sale_price_dates_to'][ $i ] ) ) {
          $date_on_sale_to = wc_clean( wp_unslash( $_POST['variable_sale_price_dates_to'][ $i ] ) );

          if ( ! empty( $date_on_sale_to ) ) {
            $date_on_sale_to = date( 'Y-m-d 23:59:59', strtotime( $date_on_sale_to ) );
          }
        }

        $errors = $variation->set_props(
          array(
            'status'            => isset( $_POST['variable_enabled'][ $i ] ) ? 'publish' : 'private',
            'menu_order'        => isset( $_POST['variation_menu_order'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variation_menu_order'][ $i ] ) ) : null,
            'regular_price'     => isset( $_POST['variable_regular_price'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_regular_price'][ $i ] ) ) : null,
            'sale_price'        => isset( $_POST['variable_sale_price'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_sale_price'][ $i ] ) ) : null,
            'virtual'           => isset( $_POST['variable_is_virtual'][ $i ] ),
            'downloadable'      => isset( $_POST['variable_is_downloadable'][ $i ] ),
            'date_on_sale_from' => $date_on_sale_from,
            'date_on_sale_to'   => $date_on_sale_to,
            'description'       => isset( $_POST['variable_description'][ $i ] ) ? wp_kses_post( wp_unslash( $_POST['variable_description'][ $i ] ) ) : null,
            'download_limit'    => isset( $_POST['variable_download_limit'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_download_limit'][ $i ] ) ) : null,
            'download_expiry'   => isset( $_POST['variable_download_expiry'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_download_expiry'][ $i ] ) ) : null,
            // Those are sanitized inside prepare_downloads.
            'downloads'         => self::prepare_downloads(
              isset( $_POST['_wc_variation_file_names'][ $variation_id ] ) ? wp_unslash( $_POST['_wc_variation_file_names'][ $variation_id ] ) : array(), // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
              isset( $_POST['_wc_variation_file_urls'][ $variation_id ] ) ? wp_unslash( $_POST['_wc_variation_file_urls'][ $variation_id ] ) : array(), // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
              isset( $_POST['_wc_variation_file_hashes'][ $variation_id ] ) ? wp_unslash( $_POST['_wc_variation_file_hashes'][ $variation_id ] ) : array() // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
            ),
            'manage_stock'      => isset( $_POST['variable_manage_stock'][ $i ] ),
            'stock_quantity'    => $stock,
            'backorders'        => isset( $_POST['variable_backorders'], $_POST['variable_backorders'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_backorders'][ $i ] ) ) : null,
            'stock_status'      => isset( $_POST['variable_stock_status'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_stock_status'][ $i ] ) ) : null,
            'image_id'          => isset( $_POST['upload_image_id'][ $i ] ) ? wc_clean( wp_unslash( $_POST['upload_image_id'][ $i ] ) ) : null,
            'attributes'        => self::prepare_set_attributes( $parent->get_attributes(), 'attribute_', $i ),
            'sku'               => isset( $_POST['variable_sku'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_sku'][ $i ] ) ) : '',
            'weight'            => isset( $_POST['variable_weight'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_weight'][ $i ] ) ) : '',
            'length'            => isset( $_POST['variable_length'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_length'][ $i ] ) ) : '',
            'width'             => isset( $_POST['variable_width'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_width'][ $i ] ) ) : '',
            'height'            => isset( $_POST['variable_height'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_height'][ $i ] ) ) : '',
            'shipping_class_id' => isset( $_POST['variable_shipping_class'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_shipping_class'][ $i ] ) ) : null,
            'tax_class'         => isset( $_POST['variable_tax_class'][ $i ] ) ? wc_clean( wp_unslash( $_POST['variable_tax_class'][ $i ] ) ) : null,
          )
        );

        if ( is_wp_error( $errors ) ) {
          WC_Admin_Meta_Boxes::add_error( $errors->get_error_message() );
        }

        
/**
 * Set variation props before save.
 *
 * @param object $variation WC_Product_Variation object.
 * @param int $i
 * @since 3.8.0
 */
        do_action( 'woocommerce_admin_process_variation_object', $variation, $i );