WordPress Force Login

<?php

/**
 * Force Login
 */
function force_login() {
    if (!is_user_logged_in()) {
        $url = home_url($_SERVER['REQUEST_URI']);

        $whitelist = [];
        // $whitelist = apply_filters('forcelogin_whitelist', []);
        $redirect = apply_filters('forcelogin_redirect', $url);
        $login = wp_login_url();
        $pattern = '/\?.*/';

        if (preg_replace($pattern, '', $url) != preg_replace($pattern, '', $login) && !in_array($url, $whitelist) ) {
            wp_safe_redirect(
                wp_login_url($redirect),
                302
            );
            exit;
        }
    }
}

add_action('init', 'force_login');