redirect from course page if not logged in

redirect.php

<?php


function convertkit_page_template_redirect()
{
    if( is_page( 'elements-one' ) && ! is_user_logged_in() )
    {
        $location = get_site_url() . '/courses/login/?redirect=' . get_permalink( $post->ID );
        wp_redirect( $location );
        die;
    }
}
add_action( 'template_redirect', 'convertkit_page_template_redirect' );