WordPress Plugin: Require Auth

cdm-require-auth.php

<?php
/**
 * Plugin Name: Require Auth
 * Plugin URI: https://gist.github.com/chrisdavidmiles/01ad21767394d6b3770197667c32526a
 * Description: Users must be logged in to WordPress to see site content. If a user is not authenticated, they will be redirected to the login screen. 
 * Author: Chris David Miles
 * Version: 0.1
 */

if ( ! defined( 'ABSPATH' ) )  die;

function is_wplogin(){
    $ABSPATH_MY = str_replace(array('\\','/'), DIRECTORY_SEPARATOR, ABSPATH);
    return (
           (  in_array($ABSPATH_MY.'wp-login.php', get_included_files()) 
           || in_array($ABSPATH_MY.'wp-register.php', get_included_files()) )
           || (isset($_GLOBALS['pagenow']) && $GLOBALS['pagenow'] === 'wp-login.php') 
           || $_SERVER['PHP_SELF']== '/wp-login.php'
           );
}

add_action('init', function () {
    if ( ! is_wplogin() && 
         ! is_user_logged_in() && 
         ! defined( 'WP_CLI' ) && 
         ! defined( 'DOING_AJAX' ) && 
         ! defined( 'DOING_CRON' ) && 
         $pagenow !== 'admin-post.php' && 
         $request['path'] !== '/wp-admin/options.php' ) {
           wp_redirect(wp_login_url( site_url( add_query_arg( array(), $wp->request ) ) ) );
           die();
        }
});