WooCommerce: Double discount on sale products with coupon - php

Question

I want to double the discount for products on sale with a coupon code.
For example: The product is on sale with a 10% discount. If I add the coupon code doublediscount I want to double that discount to 20%.
The coupon discount should have limit of 15%.
So if a product is on sale with a 30% discount, the max added discount with the coupon code should be 15%. Resulting in a 45% discount on the regular price (sale + extra discount).
My code so far is this:
add_action( 'woocommerce_before_calculate_totals', 'double_saleprice_coupon' );
function double_saleprice_coupon( $cart ) {
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return;
global $woocommerce;
$coupon_id = 'doublediscount';
// Loop through cart items (first loop)
foreach ( $cart->get_cart() as $cart_item_key => $cart_item ){
// Check if product in cart is on sale
$product = $cart_item['data'];
$cart_item_regular_price = $cart_item['data']->get_regular_price();
$cart_item_sale_price = $cart_item['data']->get_sale_price();
$cart_item_diff = $cart_item_regular_price - $cart_item_sale_price;
$cart_item_per_cent = round( $cart_item_diff / $cart_item_regular_price * 100, 0 );
if ( $product->is_on_sale() && wc_pb_is_bundled_cart_item($cart_item) === false && $cart_item_per_cent < 15 ) {
echo 'on sale';
echo $cart_item_per_cent;
}
}
}
I loop through all cart items and check if they are on sale and if the discount is below 15%. If that's the case, I want to change the discount for these cart items.
If the cart item has a discount above 15% I don't want to do anything. So the coupon code doublediscount would apply 15% to them.
I just don't know how to add/change the discount of a cart item.

Answer 1

You can use the woocommerce_coupon_get_discount_amount hook instead in combination with the following coupon settings:
Set correctly your coupon code: doublediscount
Discount type: Percentage
Amount: 15
Steps applied in this answer:
Only if the specific coupon code matches and the product is on sale
If a product is not on sale, no discount will be applied (by the else condition equal to 0. However, if this doesn't apply, you can simply remove the else condition)
Current percentage discount of the on sale product is calculated.
If this is less than the maximum added discount (15),
then the discount is doubled
If this is more, the maximum discount added (15) will be applied automatically
So you get:
function filter_woocommerce_coupon_get_discount_amount( $discount, $price_to_discount , $cart_item, $single, $coupon ) {
// Returns true when viewing the cart page & only apply for this coupon
if ( is_cart() || is_checkout() && $coupon->get_code() == 'doublediscount' ) {
// Get an instance of the WC_Product object
$product = $cart_item['data'];
// Is a WC product
if ( is_a( $product, 'WC_Product' ) ) {
// On sale
if ( $product->is_on_sale() ) {
// Regular price
$cart_item_regular_price = $product->get_regular_price();
// Sale price
$cart_item_sale_price = $product->get_sale_price();
// Calculate the percentage difference
$cart_item_diff = $cart_item_regular_price - $cart_item_sale_price;
$cart_item_percentage = round( $cart_item_diff / $cart_item_regular_price * 100, 0 );
// Get maximum added discount
$max_added_discount = $coupon->get_amount();
// Less than maximum added discount
if ( $cart_item_percentage < $max_added_discount ) {
$discount = round( ( $price_to_discount * $cart_item_percentage ) / 100, 0 );
}
} else {
$discount = 0;
}
}
}
return $discount;
}
add_filter( 'woocommerce_coupon_get_discount_amount', 'filter_woocommerce_coupon_get_discount_amount', 10, 5 );