ppom-for-woocommerce-dont-apply-discount-to-addons.php

<?php
/**
 * Don't apply coupons to the product addons from PPOM for WooCommerce plugin.
ì */
add_filter( 'woocommerce_coupon_get_discount_amount', function ( $discount, $discounting_amount, $cart_item, $single, $coupon ) {
    if ( ! function_exists( 'ppom_get_field_prices' ) || ! function_exists( 'ppom_price_get_addon_total' ) ) {
       return $discount;
    }

    if ( $coupon->is_type( 'percent' ) ) {
       $ppom_addons_total = 0;

       if ( isset( $cart_item['ppom']['fields'] ) ) {
          $product_id       = $cart_item['product_id'];
          $variation_id     = $cart_item['variation_id'] ?? '';
          $ppom_fields_post = $cart_item['ppom']['fields'];
          $product_quantity = floatval( $cart_item['quantity'] );

          if ( $ppom_fields_post ) {
             $ppom_field_prices = ppom_get_field_prices( $ppom_fields_post, $product_id, $product_quantity, $variation_id, $cart_item );
             $ppom_addons_total = ppom_price_get_addon_total( $ppom_field_prices );
          }
       }

       $adjusted_amount = $discounting_amount - $ppom_addons_total;
       if ( $adjusted_amount < 0 ) {
          $adjusted_amount = 0;
       }

       $discount = $adjusted_amount * ( $coupon->get_amount() / 100 );
    }

    return $discount;
}, 10, 5 );