Can I change the order WooCommerce Coupons are applied programmatically? - php

Question

I am developing a Woocommerce shop and want to offer all members (users logged in) 20% off their Total.
I have created a coupon called "twentypercent_off" and I am programmatically applying this using a custom function and a hook in my functions.php.
This works well.
In WC settings I have checked "Calculate coupon discounts sequentially" and this works almost as I would expect.
However what I would like is that my "twentypercent_off" is always applied last in cases where there are multiple coupons.
No matter what I have attempted to do (loop through all coupons on current order, remove all coupons, add them back in the order I desire) I find that Woo-commerce seems to always apply them in the order of monetary savings.
For example if the customer orders $100 worth of products and they have a coupon for $25 and also qualified to receive 20% off total.
I would like the total to calculate as (100 -25) * 0.8 = $60
but WC is calculating as such (100 * 0.8) - 25 = $55
I tried the following but it made no difference:
if ( is_user_logged_in() ) {
$Coupon_code = 'twentypercent_off';
$Current_Coupons = WC()->cart->get_coupons();
$Non_Prog_Coupons=array();
// loop through all current coupons
foreach( $Current_Coupons as $code => $coupon ){
if($code==$coupon_code){
WC()->cart->remove_coupon( $code );
} else {
WC()->cart->remove_coupon( $code );
$Non_Prog_Coupons[]=$code; // array of non-programmatically added coupons
}
}
// loop through non-programmatically added coupons
foreach( $Non_Prog_Coupons as $x => $code ){
WC()->cart->add_discount( $code ); // add them again
}
// add programmatically added coupon last !
WC()->cart->add_discount($Coupon_code);
}
return;
The only possible solution I have come across is to apply the 20% discount as a negative fee, which is not suitable for our purposes and would be an absolute last resort
Any ideas on how to achieve this would be greatly appreciated