WHMCS Custom affiliates redirects

gofas_custom_AffiliateClickthru.php

<?php
/**
 * Custom Affliates Redirects
 * © 2017 gofas.net
 *
*/
add_hook('AffiliateClickthru', 1, function($vars) {
	
	$affiliate_id	= (int)$vars['affiliateId'];
	$destination	= (string)'https://example.com';	// default destination after affiliate link click
	
	if ( $_REQUEST['page'] ) {							// page is the parameter name
		$destination = (string)$_REQUEST['page'];
		header( "Location: $destination" );
		exit;
	}
	if ( $vars['affiliateId'] === 1 ) {					// ID of affiliate
		$destination	= (string)'https://otherexample.com';
		header( "Location: $destination" );
		exit;
	}
	// default destination if not page parameter and not affiliate ID 
	else {
		header( "Location: $destination" );
		exit;
	}
});