seo.inc.php

<?php

/**
 * Plugin Name:     eggMUP: SEO Tools
 * Plugin URI:      https://gist.github.com/ianpegg/29d16c74fea470046c1dacb4f9dd3fb9
 * Description:     Tools for SEO tweaks.
 * Version:         1.0.1
 * Author:          Ian Pegg
 * Author URI:      https://eggcupwebdesign.com
 * php version 7.4.15
 *
 * @category Must_Use_Plugin
 * @package  WordPress_Plugin
 * @author   Ian Pegg <[email protected]>
 * @license  GNU/GPLv3 https://www.gnu.org/licenses/gpl-3.0.txt
 * @link     https://eggcupwebdesign.com
 **/

namespace EggCup\MUP\SEO;

if (!defined('ABSPATH')) {
    exit;
}


/**
 * Prevents WP from guessing which page to return whenever the page 
 * request results in a 404.
 * 
 * Letting WP guess is not necessarily a bad thing, but if you want 
 * to track _all_ 404s in analytics or have other mitigations in place
 * then you have two options:
 *  1. add a filter to 'do_redirect_guess_404_permalink' to prevent WP
 *     guessing when it encounters a 404.
 *  2. remove the 'template_redirect' to deactivate all redirects, including
 *     canonical redirects. This function does a lot of work to clean up the URL
 *     so this is the nuclear option and may have an impact on your SEO!
 * 
 * @link https://make.wordpress.org/core/2020/06/26/wordpress-5-5-better-fine-grained-control-of-redirect_guess_404_permalink/
 * @link https://developer.wordpress.org/reference/functions/redirect_canonical/
 */
add_filter('do_redirect_guess_404_permalink', '__return_false');
remove_action('template_redirect', 'redirect_canonical');


/**
 * Redirects unauthenticated users to the login prompt.
 * A handy way to stop bots from scraping staging sites.
 * Important: assumes 'development' and 'local' sites are
 * publicly inaccessible.
 *
 * @return void
 */
add_action('template_redirect', function () {
    if ('staging' === wp_get_environment_type() AND !is_admin()) {
        // For belt and braces add robots noindex meta tag to public pages:
        add_action('pre_option_blog_public', '__return_zero');

        // Redirect the user to login prompt unless they pass a GET var:
        if (!is_user_logged_in() AND !isset($_GET['viewfrontend'])) {
            auth_redirect();
        }
    }
});


/**
 * Redirect the current request to the 404 page, whilst setting
 * headers at the same time.
 *
 * Important: Only call this function if you understand why
 * you need to use it!
 *
 * @return void
 */
function Do_404_redirect()
{
    global $wp_query;

    $wp_query->set_404();
    status_header(404);
    get_template_part(404);
    exit();
}