Replace the text that is added to confirmation emails and confirmation page by the Gift Levels add-on

my_pmprogl_customize_message.php

<?php

// Copy from below here...

/*
 * Replace the text that is added to confirmation emails and confirmation page by the Gift Levels add-on
 * As written, will just show the code instead of the link to checkout with the code.
 */
function my_pmprogl_customize_message() {
	remove_filter("pmpro_email_body", "pmprogl_pmpro_email_body", 10, 2);
	add_filter("pmpro_email_body", "my_pmprogl_pmpro_email_body", 10, 2);
	remove_filter("pmpro_confirmation_message", "pmprogl_pmpro_confirmation_message");
	add_filter("pmpro_confirmation_message", "my_pmprogl_pmpro_confirmation_message");
}
add_filter("init", "my_pmprogl_customize_message");

function my_pmprogl_pmpro_email_body($body, $pmpro_email)
{
    global $wpdb, $pmprogl_gift_levels, $current_user;
    //only checkout emails, not admins
    if(strpos($pmpro_email->template, "checkout") !== false && strpos($pmpro_email->template, "admin") == false)
    {
        //get the user_id from the email
        $user_id = $wpdb->get_var("SELECT ID FROM $wpdb->users WHERE user_email = '" . $pmpro_email->data['user_email'] . "' LIMIT 1");
        $level_id = $pmpro_email->data['membership_id'];
        //get the user's last purchased gift code
        $gift_codes = get_user_meta($current_user->ID, "pmprogl_gift_codes_purchased", true);
        if(is_array($gift_codes))
            $code_id = end($gift_codes);
        if(!empty($code_id))
        {
            $discount_code = $wpdb->get_var("SELECT code FROM $wpdb->pmpro_discount_codes WHERE id = '" . intval($code_id) . "' LIMIT 1");
            if(!empty($discount_code)) {
                $body = "<p><strong>Share this discount code with your gift recipient: " . $discount_code . "</strong></p>" . $body;
			}
        }
    }
    return $body;
}

/*
	Show last purchased gift code on the confirmation page.
*/
function my_pmprogl_pmpro_confirmation_message($message)
{
	global $current_user, $pmprogl_gift_levels, $wpdb;
	
	//which level purchased
	$level_id = intval($_REQUEST['level']);	
		
	//only if there is a gift for this level
	if(!empty($pmprogl_gift_levels) && !empty($pmprogl_gift_levels[$level_id]))
	{
		//get the user's last purchased gift code
		$gift_codes = get_user_meta($current_user->ID, "pmprogl_gift_codes_purchased", true);
		
		if(is_array($gift_codes))
			$last_code_id = end($gift_codes);
		
		if(!empty($last_code_id))
		{
			$discount_code = $wpdb->get_var("SELECT code FROM $wpdb->pmpro_discount_codes WHERE id = '" . intval($last_code_id) . "' LIMIT 1");
            if(!empty($discount_code)) {
                $message = "<p><strong>Share this discount code with your gift recipient: " . $discount_code . "</strong></p>" . $message;
			}
		}
	}
	return $message;
}