Get UTM Source

utm.php

<?php
// Set cookie for new users
add_action( 'init', 'set_newuser_cookie'); // Run when WordPress loads
function set_newuser_cookie() {
	
	$cookie_value = $_SERVER["HTTP_REFERER"]; // Get URL the user came to your site for
	
	if ( !is_admin() && !isset($_COOKIE['origin'])) { // If not an admin or if cookie doesn't exist already
		setcookie( 'origin', $cookie_value, time()+3600*24*30, COOKIEPATH, COOKIE_DOMAIN, false); // Set cookie for 30 days
    		setcookie( 'utm_source', sanitize_key( $_GET['utm_source'] ), time() + ( 3 * 86400 ), COOKIEPATH, COOKIE_DOMAIN );
    		setcookie( 'utm_medium', $cookie_value, time()+3600*24*30, COOKIEPATH, COOKIE_DOMAIN, false); // Set cookie for 30 days
    		setcookie( 'utm_term', $cookie_value, time()+3600*24*30, COOKIEPATH, COOKIE_DOMAIN, false); // Set cookie for 30 days
	}
}


// Check cookie when order made and add to order
add_action('woocommerce_checkout_update_order_meta', 'add_referral_meta'); // Run when an order is made in WooCommerce

function add_referral_meta( $order_id, $posted ){
	$ref_url = $_COOKIE['origin']; // Get the cookie
  	$ref_utm_source = $_COOKIE['utm_source']; 
  	$ref_utm_medium = $_COOKIE['utm_medium'];
  	$ref_utm_term = $_COOKIE['utm_term']; 
	update_post_meta( $order_id, 'utm_source' . sanitize_key( $_COOKIE['utm_source'] ), 1 );
    	update_post_meta( $order_id, 'referrer', $ref_url ); // Add to order meta
    	update_post_meta( $order_id, 'utm_source', $ref_utm_source ); // Add to order meta utm_source
    	update_post_meta( $order_id, 'utm_medium', $ref_utm_medium ); // Add to order meta utm_medium
    	update_post_meta( $order_id, 'utm_term', $ref_utm_term ); // Add to order meta utm_medium

}