Apply Discount on Regular price instead of sale price. if sale price configured at product level then we not apply sublium discount on Subscribe and save

Apply Discount on Regular price instead of sale price. if sale price configured at product level then we not apply sublium discount on Subscribe and save

 /**
   * Force Sublium Subscribe & Save discount to calculate against
   * the product's regular price, not the sale price.
   *
   * Works on product page, cart, and checkout.
   * Place in your child theme's functions.php or a site-specific plugin.
   */
  add_filter( 'sublium_wcs_plan_price', 'sublium_sns_discount_on_regular_price', 10, 3 );

  function sublium_sns_discount_on_regular_price( $price, $product, $plan ) {
        // Only act on Subscribe & Save plans (type 1).
        if ( ! is_object( $plan ) || $plan->get_type() !== 1 ) {
                return $price;
        }

        // Only act when the product is on sale.
        if ( ! $product->is_on_sale() ) {
                return $price;
        }

        // Recalculate the discount from regular price instead.
        $regular_price = (float) $product->get_regular_price();
        if ( $regular_price <= 0 ) {
                return $price;
        }

        return \Sublium_WCS\Includes\Helpers\Discount::calculate(
                $regular_price,
                $plan->get_plan_data(),
                $product
        );
  }