Adjusts the referral amount based on whether the product is virtual or not.

affwp-wc-referral-by-product-type.php

<?php
/**
 * Plugin Name: AffiliateWP - Modify Referral If Virtual Product (WC)
 * Plugin URI: https://affiliatewp.com
 * Description: Modify referral rate 
 * Author: AffiliateWP Team
 * Author URI: https://affiliatewp.com
 * Version: 1.0
 */
function prefix_affwp_modify_referral_if_virtual( $referral_amount, $affiliate_id, $amount, $reference, $product_id ) {
    
    $new_desired_amount = '10';

    global $product;

    if( $product->product_type == 'variable' ) :

	    // Get product variations
	    $variations = $product->get_available_variations();

	    // Identifying that all variations are virtual
	    $is_virtual = array();

	    foreach ( $variations as $v ){
		    $is_virtual[] = $v['is_virtual'];
	    }

	    $is_virtual = array_unique($is_virtual);
	    $all_variations_are_virtual = false;
	    if (count($is_virtual) === 1 && end($is_virtual) === true) {
	    	$all_variations_are_virtual = true;
    	}

	// Check if current product type is variable and all variations are virtual
	if( $product->product_type == 'variable' && $all_variations_are_virtual == true  ){

		// It's a virtual product in WooCommerce
		$amount = $new_desired_amount;

	}

    endif;
}
add_filter( 'affwp_calc_referral_amount', 'prefix_affwp_modify_referral_if_virtual', 10, 5 );