Optimize your WordPress site with custom 301 redirect handling

gistfile1.txt

Copy the following PHP code and create a PHP snippet using your snippet plugins. 
Paste the code into the plugin and save it.

This code snippet will help you to easily manage all 301 redirects and so simply redirect your old links on new directly 
from wordpress admin. By using these redirects you can ensure that both human and search engine traffic gets sent to the 
appropriate pages wich helps maintain your SEO value as well improve user experience. The snippet also incorporates caching 
to ease up on database load which helps keep your site fast and efficient. It is simply a functional way of preserving the 
integrity of your sites links all integrated without needing additional plugins, so you can maintain an easy and straight 
forward workflow.

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// Register the custom menu page
function flx_redirect_menu_page() {
    add_menu_page(
        'FLX Redirect', // Page title
        'FLX Redirect', // Menu title
        'manage_options', // Capability
        'flx-redirect', // Menu slug
        'flx_redirect_admin_page', // Function to display the page
        'dashicons-randomize', // Icon
        90 // Position
    );
}
add_action('admin_menu', 'flx_redirect_menu_page');

// Display the admin page
function flx_redirect_admin_page() {
    if (!current_user_can('manage_options')) {
        wp_die(__('You do not have sufficient permissions to access this page.'));
    }

    // Handle form submission
    if (isset($_POST['flx_redirect_nonce']) && wp_verify_nonce($_POST['flx_redirect_nonce'], 'flx_redirect_save')) {
        $redirects = [];

        if (isset($_POST['flx_redirects']) && is_array($_POST['flx_redirects'])) {
            foreach ($_POST['flx_redirects'] as $redirect) {
                if (!empty($redirect['old_url']) && !empty($redirect['new_url'])) {
                    $redirects[] = [
                        'old_url' => esc_url_raw(wp_unslash(trim($redirect['old_url']))),
                        'new_url' => esc_url_raw(wp_unslash(trim($redirect['new_url']))),
                    ];
                }
            }
        }

        update_option('flx_redirects', $redirects);
        flx_redirect_clear_cache();
        echo '<div class="updated"><p>Redirects saved successfully.</p></div>';
    }

    // Get the saved redirects
    $redirects = get_option('flx_redirects', []);
    ?>
    <div class="wrap">
        <h1>FLX Redirect</h1>
        <form method="post">
            <?php wp_nonce_field('flx_redirect_save', 'flx_redirect_nonce'); ?>
            <table class="form-table" id="flx-redirect-table">
                <thead>
                    <tr>
                        <th>Old URL</th>
                        <th>New URL</th>
                        <th>Actions</th>
                    </tr>
                </thead>
                <tbody>
                    <?php if (!empty($redirects)) : ?>
                        <?php foreach ($redirects as $index => $redirect) : ?>
                            <tr>
                                <td><input type="text" name="flx_redirects[<?php echo esc_attr($index); ?>][old_url]" value="<?php echo esc_attr($redirect['old_url']); ?>" class="regular-text"></td>
                                <td><input type="text" name="flx_redirects[<?php echo esc_attr($index); ?>][new_url]" value="<?php echo esc_attr($redirect['new_url']); ?>" class="regular-text"></td>
                                <td><button type="button" class="button flx-remove-row">Remove</button></td>
                            </tr>
                        <?php endforeach; ?>
                    <?php else: ?>
                        <tr>
                            <td colspan="3">No redirects found. Add a new one below.</td>
                        </tr>
                    <?php endif; ?>
                </tbody>
            </table>
            <p>
                <button type="button" id="flx-add-row" class="button">Add Redirect</button>
            </p>
            <p>
                <input type="submit" class="button button-primary" value="Save Redirects">
            </p>
        </form>
    </div>
    <script>
    (function() {
        function addRemoveListener(button) {
            button.addEventListener('click', function() {
                this.closest('tr').remove();
            });
        }

        document.getElementById('flx-add-row').addEventListener('click', function() {
            var table = document.getElementById('flx-redirect-table').getElementsByTagName('tbody')[0];
            var rowCount = table.rows.length;
            var newRow = table.insertRow();
            newRow.innerHTML = `
                <td><input type="text" name="flx_redirects[${rowCount}][old_url]" class="regular-text"></td>
                <td><input type="text" name="flx_redirects[${rowCount}][new_url]" class="regular-text"></td>
                <td><button type="button" class="button flx-remove-row">Remove</button></td>
            `;
            addRemoveListener(newRow.querySelector('.flx-remove-row'));
        });

        document.querySelectorAll('.flx-remove-row').forEach(addRemoveListener);
    })();
    </script>
    <?php
}

// Handle the redirections efficiently with caching
function flx_redirect_handler() {
    if (is_admin()) {
        return; // Skip redirection on admin pages
    }

    // Use transient to cache redirects to avoid DB queries on every page load
    $redirects = get_transient('flx_redirects_cache');
    if ($redirects === false) {
        $redirects = get_option('flx_redirects', []);
        set_transient('flx_redirects_cache', $redirects, 12 * HOUR_IN_SECONDS); // Cache for 12 hours
    }

    $current_url = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http") . "://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
    $current_url = rtrim($current_url, '/');
    $current_domain = parse_url(home_url(), PHP_URL_HOST);

    foreach ($redirects as $redirect) {
        $old_url = rtrim($redirect['old_url'], '/');
        $new_url = rtrim($redirect['new_url'], '/');

        if ($current_url === $old_url) {
            $new_url_domain = parse_url($new_url, PHP_URL_HOST);
            
            if ($new_url_domain === $current_domain) {
                wp_safe_redirect($new_url, 301);
            } else {
                wp_redirect($new_url, 301);
            }
            exit;
        }
    }
}
add_action('template_redirect', 'flx_redirect_handler');

// Clear the cache when redirects are updated
function flx_redirect_clear_cache() {
    delete_transient('flx_redirects_cache');
}
add_action('update_option_flx_redirects', 'flx_redirect_clear_cache');