Calculate store credit from the order subtotal

Use the configured reward percentage against the order subtotal, excluding discounts, fees, shipping, and tax.

Developer note:

Add custom PHP in a small custom plugin or child theme, and test it on a staging site before production. This example requires ongoing maintenance when extension APIs change.

functions.php

<?php

add_filter( 'automatewoo/referrals/reward_amount', 'my_store_referral_subtotal_reward', 10, 3 );

/**
 * Calculate store credit from the referred order subtotal.
 *
 * @param float                          $reward_amount Existing reward amount.
 * @param AutomateWoo\Referrals\Advocate $advocate     Advocate.
 * @param WC_Order                       $order        Referred order.
 * @return float
 */
function my_store_referral_subtotal_reward( $reward_amount, $advocate, $order ) {
	if ( ! $order instanceof WC_Order ) {
		return $reward_amount;
	}

	$percentage = (float) AW_Referrals()->options()->reward_amount;

	return (float) $order->get_subtotal() * $percentage / 100;
}