Disable WordPress User Login During Maintenance

disable-wordpress-login

// MAINTAINANCE MODE
//Disables login for 'editor' and custom 'revisor' user roles.

function site_maintenance() {
    if ( current_user_can('editor') || current_user_can('revisor') ) {

       $logout_url = wp_login_url().'?mode=maintainance';
       wp_logout();
       wp_redirect( $logout_url, 302 );

    }     
}
add_action('get_header', 'site_maintenance');

// CUSTOM LOGIN MESSAGES
function my_login_message() {

    if( $_GET['mode'] == 'maintainance' ){
        $message = '<p class="message"><b>Site undergoing maintainance.</b></p>';
        return $message;
    }

}
add_filter('login_message', 'my_login_message');