<?php

function custom_referral_amounts( $referral_amount, $affiliate_id, $amount, $reference, $product_id ) {

    $user_id        = affwp_get_affiliate_user_id( $affiliate_id );
    $member         = new MeprUser( $user_id );
    $subscriptions  = array_unique( $member->active_product_subscriptions( 'products' ) );

    $user_level = 'freshman';

    foreach( $subscriptions as $product ) {

        if( strpos($product->post_title, 'Sophomore') !== false ) {

            $user_level = 'sophomore';
            break;

        } elseif( strpos($product->post_title, 'Junior') !== false ) {

            $user_level = 'junior';
            break;

        } elseif( strpos($product->post_title, 'Senior') !== false ) {

            $user_level = 'senior';
            break;

        } elseif( strpos($product->post_title, 'Graduate') !== false ) {

            $user_level = 'graduate';
            break;

        }

    }

    // Now we know the user level

    if( $user_level == 'freshman' ) {

        $referral_amount = $amount * 0.20;

        if( $referral_amount > 10 ) {
            $referral_amount = 10;
        }

    } elseif( $user_level == 'sophomore' ) {

        $referral_amount = $amount * 0.50;

        if( $referral_amount > 25 ) {
            $referral_amount = 25;
        }

    } elseif( $user_level == 'junior' ) {

        $referral_amount = $amount * 0.50;

        if( $referral_amount > 100 ) {
            $referral_amount = 100;
        }

    } elseif( $user_level == 'senior' ) {

        $referral_amount = $amount * 0.50;

        if( $referral_amount > 250 ) {
            $referral_amount = 250;
        }

    } elseif( $user_level == 'graduate' ) {

        $referral_amount = $amount * 0.50;

        if( $referral_amount > 500 ) {
            $referral_amount = 500;
        }

    }

    return $referral_amount;

}

add_filter( 'affwp_calc_referral_amount', 'custom_referral_amounts', 10, 5 );