Woocommerce coupon discount on product regular price (not sale price) - coupon

Question

In WooCommerce there's regular price X and sales price Y.
I would like to add a specific coupon with a code for a 50 discount to be taken from the regular price X.
I would like the coupon to disregard the sale price so I get X-50 NOT Y-50. But when the specific coupon is not applied price Y is used.
I found the following which works for all coupons, but I need the solution to work for a specific coupon:
add_action( 'woocommerce_before_calculate_totals', 'add_custom_price', 10, 1);
function add_custom_price( $cart_object) {
global $woocommerce;
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return;
$coupon = False;
if ($coupons = WC()->cart->get_applied_coupons() == False )
$coupon = False;
else {
foreach ( WC()->cart->get_applied_coupons() as $code ) {
$coupons1 = new WC_Coupon( $code );
if ($coupons1->type == 'percent_product' || $coupons1->type == 'percent')
$coupon = True;
}
}
if ($coupon == True)
foreach ( $cart_object->get_cart() as $cart_item )
{
$price = $cart_item['data']->regular_price;
$cart_item['data']->set_price( $price );
}
}