<?php
/**
 * Plugin Name: AI 404 Redirect
 * Plugin URI: https://domin8x.com/wordpress/plugins/ai-404-redirect
 * Description: Intelligently redirects 404 errors using AI to find the best matching content on your WordPress site. Reduces bounce rates and improves user experience with smart content matching.
 * Version: 1.0.0
 * Requires at least: 5.0
 * Tested up to: 6.8
 * Requires PHP: 7.4
 * Author: Domin8x
 * Author URI: https://domin8x.com
 * License: GPLv2 or later
 * License URI: https://www.gnu.org/licenses/gpl-2.0.html
 * Text Domain: ai-404-redirect
 * Domain Path: /languages
 */

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

define('AI_404_REDIRECT_VERSION', '1.0.0');

class AI_404_Redirect {
    
    private static $instance = null;
    
    // API configuration
    private $api_endpoint = 'https://text.pollinations.ai/openai';
    private $api_model = 'gpt-5-nano';
    private $api_key = 'dummy';
    private $temperature = 1;
    
    public static function get_instance() {
        if (null === self::$instance) {
            self::$instance = new self();
        }
        return self::$instance;
    }
    
    private function __construct() {
        add_action('init', array($this, 'init'));
        register_activation_hook(__FILE__, array($this, 'activate'));
        register_deactivation_hook(__FILE__, array($this, 'deactivate'));
    }
    
    public function init() {
        // Use high priority to override WordPress built-in redirects
        add_action('template_redirect', array($this, 'handle_404'), 1);
        add_action('admin_menu', array($this, 'add_admin_menu'));
        add_action('admin_notices', array($this, 'admin_notices'));
        add_action('admin_enqueue_scripts', array($this, 'admin_enqueue_styles'));
        
        // Disable WordPress's built-in redirect guessing
        add_filter('redirect_canonical', array($this, 'disable_wp_redirect_guess'), 1, 2);
        
        // Hook into WordPress events to detect URL changes
        add_action('post_updated', array($this, 'handle_post_url_change'), 10, 3);
        add_action('edited_term', array($this, 'handle_term_url_change'), 10, 3);
        add_action('wp_update_nav_menu_item', array($this, 'handle_menu_url_change'), 10, 3);
        
        // Check if tables exist, create if not
        $this->ensure_tables();
    }
    
    public function admin_enqueue_styles($hook) {
        // Only load on our plugin pages
        if (strpos($hook, 'ai-404-redirect') !== false || $hook === 'toplevel_page_ai-404-redirect') {
            wp_enqueue_style(
                'ai-404-redirect-admin',
                plugin_dir_url(__FILE__) . 'assets/admin-style.css',
                array(),
                AI_404_REDIRECT_VERSION
            );
        }
    }
    
    public function activate() {
        $this->create_tables();
        
        // Store version for future upgrades
        add_option('ai_404_redirect_version', AI_404_REDIRECT_VERSION);
        
        // Flush rewrite rules to ensure proper URL handling
        flush_rewrite_rules();
    }
    
    public function deactivate() {
        // Flush rewrite rules on deactivation
        flush_rewrite_rules();
    }
    
    private function create_tables() {
        global $wpdb;
        $charset_collate = $wpdb->get_charset_collate();
        
        // Create 404 hits table
        $hits_table = $wpdb->prefix . 'ai_404_redirect_hits';
        $hits_sql = "CREATE TABLE $hits_table (
            id mediumint(9) NOT NULL AUTO_INCREMENT,
            url varchar(500) NOT NULL,
            first_hit datetime DEFAULT CURRENT_TIMESTAMP,
            hit_count int DEFAULT 1,
            last_hit datetime DEFAULT CURRENT_TIMESTAMP,
            redirected_to varchar(500),
            user_agent text,
            referer varchar(500),
            PRIMARY KEY (id),
            UNIQUE KEY url (url),
            KEY first_hit (first_hit)
        ) $charset_collate;";
        
        require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
        dbDelta($hits_sql);
        
        // Create manual redirects table
        $redirects_table = $wpdb->prefix . 'ai_404_manual_redirects';
        $redirects_sql = "CREATE TABLE $redirects_table (
            id mediumint(9) NOT NULL AUTO_INCREMENT,
            from_url varchar(500) NOT NULL,
            to_url varchar(500) NOT NULL,
            redirect_type int DEFAULT 302,
            is_active tinyint(1) DEFAULT 1,
            created_at datetime DEFAULT CURRENT_TIMESTAMP,
            hit_count int DEFAULT 0,
            PRIMARY KEY (id),
            UNIQUE KEY from_url (from_url),
            KEY is_active (is_active)
        ) $charset_collate;";
        
        dbDelta($redirects_sql);
    }
    
    private function ensure_tables() {
        global $wpdb;
        
        // Check if manual redirects table exists
        $manual_table = $wpdb->prefix . 'ai_404_manual_redirects';
        $table_exists = $wpdb->get_var($wpdb->prepare("SHOW TABLES LIKE %s", $manual_table)) === $manual_table; // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
        
        if (!$table_exists) {
            $this->create_tables();
        }
    }
    
    public function handle_404() {
        if (is_404()) {
            $requested_url = isset($_SERVER['REQUEST_URI']) ? sanitize_text_field(wp_unslash($_SERVER['REQUEST_URI'])) : '';
            
            if (empty($requested_url)) {
                return;
            }
            
            // Track 404 hit
            $this->track_404_hit($requested_url);
            
            // Check for manual redirect first
            $manual_redirect = $this->get_manual_redirect($requested_url);
            if ($manual_redirect) {
                // Get final destination to prevent redirect chains
                $final_destination = $this->resolve_redirect_chain($manual_redirect['to_url']);
                $this->increment_manual_redirect_count($manual_redirect['id']);
                $redirect_url = $this->get_full_redirect_url($final_destination);
                $this->update_404_redirect($requested_url, $final_destination);
                wp_redirect($redirect_url, $manual_redirect['redirect_type']);
                exit;
            }
            
            // Check if we already have a cached redirect for this URL
            $cached_redirect = $this->get_cached_404_redirect($requested_url);
            if ($cached_redirect) {
                // Get final destination to prevent redirect chains
                $final_destination = $this->resolve_redirect_chain($cached_redirect);
                // Verify the final redirect target still exists
                if ($this->verify_redirect_target($final_destination)) {
                    // Update cache if destination changed due to chain resolution
                    if ($final_destination !== $cached_redirect) {
                        $this->update_404_redirect($requested_url, $final_destination);
                    }
                    $redirect_url = home_url($final_destination);
                    wp_redirect($redirect_url, 302);
                    exit;
                } else {
                    $this->clear_404_redirect_cache($requested_url);
                }
            }
            
            // If no manual or cached redirect, use AI
            $best_match = $this->find_best_match($requested_url);
            
            if ($best_match && $best_match !== $requested_url) {
                // Update redirect info before redirecting
                $this->update_404_redirect($requested_url, $best_match);
                
                // Force database write before redirect
                global $wpdb;
                if (function_exists('wp_cache_flush')) {
                    wp_cache_flush();
                }
                
                $redirect_url = home_url($best_match);
                wp_redirect($redirect_url, 302);
                exit;
            }
        }
    }
    
    private function find_best_match($requested_url) {
        $available_routes = $this->get_available_routes();
        
        if (empty($available_routes)) {
            return null;
        }
        
        $ai_response = $this->query_ai($requested_url, $available_routes);
        if ($ai_response === null) {
            return null;
        }
        
        return $this->parse_ai_response($ai_response, $available_routes);
    }
    
    private function get_available_routes() {
        $routes = array();
        
        // Add homepage
        $routes[] = home_url('/');
        
        // Get all published posts and pages
        $posts = get_posts(array(
            'post_type' => array('post', 'page'),
            'post_status' => 'publish',
            'numberposts' => -1
        ));
        
        foreach ($posts as $post) {
            $routes[] = get_permalink($post->ID);
        }
        
        // Get category and tag archives
        $categories = get_categories();
        foreach ($categories as $category) {
            $routes[] = get_category_link($category->term_id);
        }
        
        $tags = get_tags();
        foreach ($tags as $tag) {
            $routes[] = get_tag_link($tag->term_id);
        }
        
        // Remove home URL from routes to get relative paths and clean up URLs
        $home_url = home_url();
        $routes = array_map(function($route) use ($home_url) {
            $relative_path = str_replace($home_url, '', $route);
            // Remove /index.php/ if present
            $relative_path = str_replace('/index.php/', '/', $relative_path);
            // Ensure path starts with /
            if ($relative_path && $relative_path[0] !== '/') {
                $relative_path = '/' . $relative_path;
            }
            // If empty path, it's homepage
            if (empty($relative_path) || $relative_path === '/') {
                return '/';
            }
            return $relative_path;
        }, $routes);
        
        return array_unique($routes);
    }
    
    private function query_ai($requested_url, $available_routes) {
        $prompt = "A user tried to access: {$requested_url}\n\n";
        $prompt .= "Available routes:\n" . implode("\n", $available_routes) . "\n\n";
        $prompt .= "Find the most relevant and related route from the available routes. Be creative and consider:\n";
        $prompt .= "- Similar topics (e.g., 'rocket' relates to 'spacex', 'space', 'nasa')\n";
        $prompt .= "- Related keywords and synonyms\n";
        $prompt .= "- Conceptual connections\n";
        $prompt .= "- Partial matches and variations\n";
        $prompt .= "Return only the exact route path from the list above, nothing else.";
        
        $data = array(
            'model' => $this->api_model,
            'messages' => array(
                array(
                    'role' => 'user',
                    'content' => $prompt
                )
            ),
            'max_tokens' => 100,
            'temperature' => $this->temperature
        );
        
        $args = array(
            'headers' => array(
                'Content-Type' => 'application/json',
                'Authorization' => 'Bearer ' . $this->api_key
            ),
            'body' => json_encode($data),
            'timeout' => 30
        );
        
        $response = wp_remote_post($this->api_endpoint, $args);
        
        if (is_wp_error($response)) {
            return null;
        }
        
        $response_code = wp_remote_retrieve_response_code($response);
        $body = wp_remote_retrieve_body($response);
        
        if ($response_code !== 200) {
            return null;
        }
        
        $data = json_decode($body, true);
        
        if (json_last_error() !== JSON_ERROR_NONE) {
            return null;
        }
        
        if (isset($data['choices'][0]['message']['content'])) {
            return trim($data['choices'][0]['message']['content']);
        }
        
        return null;
    }
    
    private function parse_ai_response($ai_response, $available_routes) {
        if (empty($ai_response)) {
            return null;
        }
        
        // Clean up the AI response
        $ai_response = trim($ai_response, " \t\n\r\0\x0B\"'");
        
        // First try exact match
        foreach ($available_routes as $route) {
            if ($ai_response === $route) {
                return $route;
            }
        }
        
        // Then try if AI response is contained in any route (but avoid matching "/" with everything)
        foreach ($available_routes as $route) {
            if ($route !== '/' && strpos($route, $ai_response) !== false) {
                return $route;
            }
        }
        
        // Then try if any route is contained in AI response (but avoid matching "/" with everything) 
        foreach ($available_routes as $route) {
            if ($route !== '/' && strpos($ai_response, $route) !== false) {
                return $route;
            }
        }
        
        // Finally, check if AI response matches homepage specifically
        if ($ai_response === '/' || $ai_response === 'home' || $ai_response === 'homepage') {
            return '/';
        }
        
        return null;
    }
    
    public function disable_wp_redirect_guess($redirect_url, $requested_url) {
        // Disable WordPress's redirect guessing when on 404 pages
        if (is_404()) {
            return false;
        }
        
        return $redirect_url;
    }
    
    private function get_cached_404_redirect($url) {
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_redirect_hits';
        
        $cached = $wpdb->get_var($wpdb->prepare( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            "SELECT redirected_to FROM `{$table_name}` WHERE url = %s AND redirected_to IS NOT NULL AND redirected_to != ''", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
            $url
        ));
        
        return $cached;
    }
    
    private function verify_redirect_target($target_path) {
        $target_url = home_url($target_path);
        $response = wp_remote_head($target_url, array(
            'timeout' => 5,
            'redirection' => 0
        ));
        
        if (is_wp_error($response)) {
            return false;
        }
        
        $status_code = wp_remote_retrieve_response_code($response);
        return ($status_code !== 404 && $status_code !== 500);
    }
    
    private function clear_404_redirect_cache($url) {
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_redirect_hits';
        
        $wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            $table_name,
            array('redirected_to' => null),
            array('url' => $url),
            array('%s'),
            array('%s')
        );
    }
    
    private function get_manual_redirect($url) {
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_manual_redirects';
        
        $redirect = $wpdb->get_row($wpdb->prepare( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            "SELECT * FROM `{$table_name}` WHERE from_url = %s AND is_active = 1", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
            $url
        ), ARRAY_A);
        
        return $redirect;
    }
    
    private function get_full_redirect_url($to_url) {
        // If it starts with http/https, it's already a full URL
        if (strpos($to_url, 'http://') === 0 || strpos($to_url, 'https://') === 0) {
            return $to_url;
        }
        
        // If it starts with /, it's a relative path - convert to full URL
        if (strpos($to_url, '/') === 0) {
            return home_url($to_url);
        }
        
        // If it doesn't start with /, assume it's a relative path and add /
        return home_url('/' . $to_url);
    }
    
    private function increment_manual_redirect_count($redirect_id) {
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_manual_redirects';
        
        $wpdb->query($wpdb->prepare( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            "UPDATE `{$table_name}` SET hit_count = hit_count + 1 WHERE id = %d", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
            $redirect_id
        ));
    }
    
    private function track_404_hit($url) {
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_redirect_hits';
        
        $user_agent = isset($_SERVER['HTTP_USER_AGENT']) ? sanitize_text_field(wp_unslash($_SERVER['HTTP_USER_AGENT'])) : '';
        $referer = isset($_SERVER['HTTP_REFERER']) ? esc_url_raw(wp_unslash($_SERVER['HTTP_REFERER'])) : '';
        $url = sanitize_text_field($url);
        
        $existing = $wpdb->get_row($wpdb->prepare( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            "SELECT * FROM `{$table_name}` WHERE url = %s", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
            $url
        ));
        
        if ($existing) {
            $wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
                $table_name,
                array(
                    'hit_count' => absint($existing->hit_count) + 1,
                    'last_hit' => current_time('mysql')
                ),
                array('url' => $url),
                array('%d', '%s'),
                array('%s')
            );
        } else {
            $wpdb->insert( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
                $table_name,
                array(
                    'url' => $url,
                    'user_agent' => $user_agent,
                    'referer' => $referer
                ),
                array('%s', '%s', '%s')
            );
        }
    }
    
    private function update_404_redirect($url, $redirected_to) {
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_redirect_hits';
        
        $wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            $table_name,
            array('redirected_to' => $redirected_to),
            array('url' => $url),
            array('%s'),
            array('%s')
        );
    }
    
    public function add_admin_menu() {
        // Add main menu page
        add_menu_page(
            'AI 404 Redirect',
            'AI 404 Redirect',
            'manage_options',
            'ai-404-redirect',
            array($this, 'hits_page'),
            'dashicons-redo',
            30
        );
        
        // Add submenu pages
        add_submenu_page(
            'ai-404-redirect',
            '404 Hits History',
            '404 Hits',
            'manage_options',
            'ai-404-redirect',
            array($this, 'hits_page')
        );
        
        add_submenu_page(
            'ai-404-redirect',
            'Manual Redirects',
            'Manual Redirects',
            'manage_options',
            'ai-404-redirect-manual',
            array($this, 'manual_redirects_page')
        );
    }
    
    public function hits_page() {
        // Check user permissions
        if (!current_user_can('manage_options')) {
            wp_die(esc_html__('You do not have sufficient permissions to access this page.', 'ai-404-redirect'));
        }
        
        if (isset($_POST['clear_hits']) && check_admin_referer('clear_404_hits', 'clear_hits_nonce')) {
            $this->clear_404_hits();
            echo '<div class="notice notice-success"><p>' . esc_html__('404 hits cleared successfully!', 'ai-404-redirect') . '</p></div>';
        }
        
        if (isset($_POST['fix_chains']) && check_admin_referer('fix_redirect_chains', 'fix_chains_nonce')) {
            $this->fix_existing_redirect_chains();
            echo '<div class="notice notice-success"><p>' . esc_html__('Redirect chains have been resolved and fixed!', 'ai-404-redirect') . '</p></div>';
        }
        
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_redirect_hits';
        
        $hits = $wpdb->get_results( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            "SELECT * FROM `{$table_name}` ORDER BY first_hit DESC LIMIT 200", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
            ARRAY_A
        );
        
        ?>
        <div class="wrap">
            <h1><?php echo esc_html__('404 Hits History', 'ai-404-redirect'); ?></h1>
            
            <div style="margin-bottom: 20px;">
                <form method="post" action="" style="display: inline-block; margin-right: 10px;">
                    <?php wp_nonce_field('clear_404_hits', 'clear_hits_nonce'); ?>
                    <?php submit_button(__('Clear All 404 Hits', 'ai-404-redirect'), 'secondary', 'clear_hits', false, array('onclick' => 'return confirm("' . esc_js(__('Are you sure you want to clear all 404 hits? This action cannot be undone.', 'ai-404-redirect')) . '")')); ?>
                </form>
                <form method="post" action="" style="display: inline-block;">
                    <?php wp_nonce_field('fix_redirect_chains', 'fix_chains_nonce'); ?>
                    <?php submit_button(__('Fix Redirect Chains', 'ai-404-redirect'), 'primary', 'fix_chains', false, array('onclick' => 'return confirm("' . esc_js(__('This will resolve any redirect chains in your manual redirects and cached 404 redirects. Continue?', 'ai-404-redirect')) . '")')); ?>
                </form>
            </div>
            
            <?php if (empty($hits)): ?>
                <p><?php echo esc_html__('No 404 hits recorded yet.', 'ai-404-redirect'); ?></p>
            <?php else: ?>
                <table class="wp-list-table widefat fixed striped">
                    <thead>
                        <tr>
                            <th><?php echo esc_html__('URL', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('First Hit', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Hit Count', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Last Hit', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Redirected To', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Referer', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Actions', 'ai-404-redirect'); ?></th>
                        </tr>
                    </thead>
                    <tbody>
                        <?php foreach ($hits as $hit): ?>
                            <tr>
                                <td><code><?php echo esc_html($hit['url']); ?></code></td>
                                <td><?php echo esc_html($hit['first_hit']); ?></td>
                                <td><span class="hit-count"><?php echo esc_html($hit['hit_count']); ?></span></td>
                                <td><?php echo esc_html($hit['last_hit']); ?></td>
                                <td>
                                    <?php if ($hit['redirected_to']): ?>
                                        <span class="redirected">→ <?php echo esc_html($hit['redirected_to']); ?></span>
                                    <?php else: ?>
                                        <span class="no-redirect"><?php echo esc_html__('No redirect', 'ai-404-redirect'); ?></span>
                                    <?php endif; ?>
                                </td>
                                <td>
                                    <?php if ($hit['referer']): ?>
                                        <a href="<?php echo esc_url($hit['referer']); ?>" target="_blank">View</a>
                                    <?php else: ?>
                                        <span class="no-referer"><?php echo esc_html__('Direct', 'ai-404-redirect'); ?></span>
                                    <?php endif; ?>
                                </td>
                                <td>
                                    <?php 
                                    $manual_url = admin_url('options-general.php?page=ai-404-redirect-manual&from_url=' . urlencode($hit['url']));
                                    if ($hit['redirected_to']) {
                                        $manual_url .= '&to_url=' . urlencode($hit['redirected_to']);
                                    }
                                    ?>
                                    <a href="<?php echo esc_url($manual_url); ?>" 
                                       class="button button-small button-primary">
                                        <?php echo esc_html__('Edit', 'ai-404-redirect'); ?>
                                    </a>
                                </td>
                            </tr>
                        <?php endforeach; ?>
                    </tbody>
                </table>
            <?php endif; ?>
            
            <div class="d8x-footer">
                <p><strong>AI 404 Redirect</strong> by <a href="https://domin8x.com" target="_blank">Domin8x</a> | Need custom WordPress development? <a href="https://domin8x.com/contact" target="_blank">Get in touch!</a></p>
            </div>
        </div>
        <?php
    }
    
    public function manual_redirects_page() {
        // Check user permissions
        if (!current_user_can('manage_options')) {
            wp_die(esc_html__('You do not have sufficient permissions to access this page.', 'ai-404-redirect'));
        }
        
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_manual_redirects';
        
        // Handle form submissions
        if (isset($_POST['add_redirect']) && check_admin_referer('add_manual_redirect', 'redirect_nonce')) {
            $from_url = isset($_POST['from_url']) ? sanitize_text_field(wp_unslash($_POST['from_url'])) : '';
            $to_url = isset($_POST['to_url']) ? sanitize_text_field(wp_unslash($_POST['to_url'])) : '';
            $redirect_type = isset($_POST['redirect_type']) ? absint($_POST['redirect_type']) : 302;
            
            // Auto-format URLs
            if (!empty($from_url) && strpos($from_url, '/') !== 0) {
                $from_url = '/' . $from_url;
            }
            
            if (!empty($to_url) && strpos($to_url, '/') !== 0 && strpos($to_url, 'http://') !== 0 && strpos($to_url, 'https://') !== 0) {
                $to_url = '/' . $to_url;
            }
            
            if (!empty($from_url) && !empty($to_url)) {
                // Check if URL already exists in manual redirects
                $existing = $wpdb->get_row($wpdb->prepare( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
                    "SELECT * FROM `{$table_name}` WHERE from_url = %s", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
                    $from_url
                ));
                
                if ($existing) {
                    /* translators: %s is the URL that already has a redirect */
                    echo '<div class="notice notice-error"><p>' . sprintf(esc_html__('Error: A redirect for "%s" already exists. Please delete the existing one first or use a different URL.', 'ai-404-redirect'), esc_html($from_url)) . '</p></div>';
                } else {
                    // Check if this URL exists in 404 hits table to transfer hit count
                    $hits_table = $wpdb->prefix . 'ai_404_redirect_hits';
                    $hit_record = $wpdb->get_row($wpdb->prepare( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
                        "SELECT * FROM `{$hits_table}` WHERE url = %s", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
                        $from_url
                    ));
                    
                    $hit_count = $hit_record ? $hit_record->hit_count : 0;
                    
                    $result = $wpdb->insert( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
                        $table_name,
                        array(
                            'from_url' => $from_url,
                            'to_url' => $to_url,
                            'redirect_type' => $redirect_type,
                            'hit_count' => $hit_count
                        ),
                        array('%s', '%s', '%d', '%d')
                    );
                    
                    if ($result) {
                        // If this was created from a 404 hit, remove the 404 hit record
                        if ($hit_record) {
                            $wpdb->delete($hits_table, array('url' => $from_url), array('%s')); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
                        }
                        
                        if ($hit_count > 0) {
                            /* translators: %d is the number of hits transferred from 404 history */
                            $success_msg = sprintf(__('Manual redirect added successfully! Transferred %d hits from 404 history.', 'ai-404-redirect'), $hit_count);
                        } else {
                            $success_msg = __('Manual redirect added successfully!', 'ai-404-redirect');
                        }
                        echo '<div class="notice notice-success"><p>' . esc_html($success_msg) . '</p></div>';
                    } else {
                        /* translators: %s is the database error message */
                        echo '<div class="notice notice-error"><p>' . sprintf(esc_html__('Database error: %s', 'ai-404-redirect'), esc_html($wpdb->last_error)) . '</p></div>';
                    }
                }
            } else {
                echo '<div class="notice notice-error"><p>' . esc_html__('Error: Both From URL and To URL are required.', 'ai-404-redirect') . '</p></div>';
            }
        }
        
        if (isset($_POST['delete_redirect']) && isset($_POST['redirect_id']) && check_admin_referer('delete_redirect_' . absint($_POST['redirect_id']))) {
            $redirect_id = absint($_POST['redirect_id']);
            $wpdb->delete($table_name, array('id' => $redirect_id), array('%d')); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            echo '<div class="notice notice-success"><p>' . esc_html__('Redirect deleted successfully!', 'ai-404-redirect') . '</p></div>';
        }
        
        if (isset($_POST['toggle_redirect']) && isset($_POST['redirect_id']) && isset($_POST['is_active']) && check_admin_referer('toggle_redirect_' . absint($_POST['redirect_id']))) {
            $redirect_id = absint($_POST['redirect_id']);
            $is_active = absint($_POST['is_active']) ? 0 : 1;
            $wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
                $table_name,
                array('is_active' => $is_active),
                array('id' => $redirect_id),
                array('%d'),
                array('%d')
            );
            echo '<div class="notice notice-success"><p>' . esc_html__('Redirect status updated!', 'ai-404-redirect') . '</p></div>';
        }
        
        $redirects = $wpdb->get_results("SELECT * FROM `{$table_name}` ORDER BY created_at DESC", ARRAY_A); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
        
        ?>
        <div class="wrap">
            <h1><?php echo esc_html__('Manual Redirects', 'ai-404-redirect'); ?></h1>
            
            <h2><?php echo esc_html__('Add New Redirect', 'ai-404-redirect'); ?></h2>
            <?php 
            $prefill_from = isset($_GET['from_url']) ? sanitize_text_field(wp_unslash($_GET['from_url'])) : '';
            $prefill_to = isset($_GET['to_url']) ? sanitize_text_field(wp_unslash($_GET['to_url'])) : '';
            if ($prefill_from): 
            ?>
                <div class="notice notice-info">
                    <p><strong>Creating manual redirect for:</strong> <code><?php echo esc_html($prefill_from); ?></code></p>
                </div>
            <?php endif; ?>
            
            <form method="post" action="">
                <?php wp_nonce_field('add_manual_redirect', 'redirect_nonce'); ?>
                <table class="form-table">
                    <tr>
                        <th scope="row"><?php echo esc_html__('From URL', 'ai-404-redirect'); ?></th>
                        <td>
                            <input type="text" name="from_url" value="<?php echo esc_attr($prefill_from); ?>" placeholder="/old-page" size="40" required />
                            <p class="description"><?php echo esc_html__('The URL to redirect from (e.g., /old-page)', 'ai-404-redirect'); ?></p>
                        </td>
                    </tr>
                    <tr>
                        <th scope="row"><?php echo esc_html__('To URL', 'ai-404-redirect'); ?></th>
                        <td>
                            <input type="text" name="to_url" value="<?php echo esc_attr($prefill_to); ?>" placeholder="/new-page or https://example.com/page" size="40" required />
                            <p class="description"><?php echo esc_html__('Destination: Use /relative-path or full https://example.com URL', 'ai-404-redirect'); ?></p>
                        </td>
                    </tr>
                    <tr>
                        <th scope="row"><?php echo esc_html__('Redirect Type', 'ai-404-redirect'); ?></th>
                        <td>
                            <select name="redirect_type">
                                <option value="301"><?php echo esc_html__('301 - Permanent', 'ai-404-redirect'); ?></option>
                                <option value="302" selected><?php echo esc_html__('302 - Temporary', 'ai-404-redirect'); ?></option>
                            </select>
                            <p class="description"><?php echo esc_html__('301 for permanent redirects, 302 for temporary', 'ai-404-redirect'); ?></p>
                        </td>
                    </tr>
                </table>
                <?php submit_button(__('Add Redirect', 'ai-404-redirect'), 'primary', 'add_redirect'); ?>
            </form>
            
            <h2><?php echo esc_html__('Existing Redirects', 'ai-404-redirect'); ?></h2>
            <?php if (empty($redirects)): ?>
                <p><?php echo esc_html__('No manual redirects created yet.', 'ai-404-redirect'); ?></p>
            <?php else: ?>
                <table class="wp-list-table widefat fixed striped">
                    <thead>
                        <tr>
                            <th><?php echo esc_html__('From URL', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('To URL', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Type', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Status', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Hits', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Created', 'ai-404-redirect'); ?></th>
                            <th><?php echo esc_html__('Actions', 'ai-404-redirect'); ?></th>
                        </tr>
                    </thead>
                    <tbody>
                        <?php foreach ($redirects as $redirect): ?>
                            <tr>
                                <td><code><?php echo esc_html($redirect['from_url']); ?></code></td>
                                <td><a href="<?php echo esc_url($redirect['to_url']); ?>" target="_blank"><?php echo esc_html($redirect['to_url']); ?></a></td>
                                <td><span class="redirect-type-<?php echo esc_attr($redirect['redirect_type']); ?>"><?php echo esc_html($redirect['redirect_type']); ?></span></td>
                                <td>
                                    <?php if ($redirect['is_active']): ?>
                                        <span class="status-active"><?php echo esc_html__('Active', 'ai-404-redirect'); ?></span>
                                    <?php else: ?>
                                        <span class="status-inactive"><?php echo esc_html__('Inactive', 'ai-404-redirect'); ?></span>
                                    <?php endif; ?>
                                </td>
                                <td><?php echo esc_html($redirect['hit_count']); ?></td>
                                <td><?php echo esc_html($redirect['created_at']); ?></td>
                                <td>
                                    <form method="post" style="display: inline;">
                                        <?php wp_nonce_field('toggle_redirect_' . $redirect['id']); ?>
                                        <input type="hidden" name="redirect_id" value="<?php echo absint($redirect['id']); ?>" />
                                        <input type="hidden" name="is_active" value="<?php echo absint($redirect['is_active']); ?>" />
                                        <button type="submit" name="toggle_redirect" class="button button-small">
                                            <?php echo $redirect['is_active'] ? esc_html__('Disable', 'ai-404-redirect') : esc_html__('Enable', 'ai-404-redirect'); ?>
                                        </button>
                                    </form>
                                    <form method="post" style="display: inline;">
                                        <?php wp_nonce_field('delete_redirect_' . $redirect['id']); ?>
                                        <input type="hidden" name="redirect_id" value="<?php echo absint($redirect['id']); ?>" />
                                        <button type="submit" name="delete_redirect" class="button button-small button-link-delete" 
                                                onclick="return confirm('<?php echo esc_js(__('Are you sure you want to delete this redirect?', 'ai-404-redirect')); ?>')"><?php echo esc_html__('Delete', 'ai-404-redirect'); ?></button>
                                    </form>
                                </td>
                            </tr>
                        <?php endforeach; ?>
                    </tbody>
                </table>
            <?php endif; ?>
            
            <div class="d8x-footer">
                <p><strong>AI 404 Redirect</strong> by <a href="https://domin8x.com" target="_blank">Domin8x</a> | Need custom WordPress development? <a href="https://domin8x.com/contact" target="_blank">Get in touch!</a></p>
            </div>
        </div>
        <?php
    }
    
    private function get_conflicting_plugins() {
        $conflicting_plugins = array();
        
        // Check for common redirect/SEO plugins
        $plugins_to_check = array(
            'seo-by-rankmath/rank-math.php' => 'RankMath SEO',
            'wordpress-seo/wp-seo-main.php' => 'Yoast SEO',
            'redirection/redirection.php' => 'Redirection',
            'simple-301-redirects/wp-simple-301-redirects.php' => 'Simple 301 Redirects',
            'safe-redirect-manager/safe-redirect-manager.php' => 'Safe Redirect Manager',
            'quick-page-post-redirect-plugin/page_post_redirect_plugin.php' => 'Quick Page/Post Redirect'
        );
        
        foreach ($plugins_to_check as $plugin_file => $plugin_name) {
            if (is_plugin_active($plugin_file)) {
                $conflicting_plugins[] = $plugin_name;
            }
        }
        
        // Also check for common classes
        $class_checks = array(
            'RankMath' => 'RankMath SEO',
            'WPSEO_Options' => 'Yoast SEO',
            'Red_Item' => 'Redirection Plugin'
        );
        
        foreach ($class_checks as $class_name => $plugin_name) {
            if (class_exists($class_name) && !in_array($plugin_name, $conflicting_plugins)) {
                $conflicting_plugins[] = $plugin_name;
            }
        }
        
        return $conflicting_plugins;
    }
    
    public function admin_notices() {
        if (current_user_can('manage_options')) {
            $conflicting_plugins = $this->get_conflicting_plugins();
            
            if (!empty($conflicting_plugins)) {
                echo '<div class="notice notice-warning">';
                echo '<p><strong>⚠️ AI 404 Redirect Notice:</strong> The following redirect/SEO plugins are active: <strong>' . esc_html(implode(', ', $conflicting_plugins)) . '</strong></p>';
                echo '<p>These plugins may interfere with AI-powered 404 redirects. Consider disabling their 404 redirect features for best results.</p>';
                echo '</div>';
            }
        }
    }
    
    private function clear_404_hits() {
        global $wpdb;
        $table_name = $wpdb->prefix . 'ai_404_redirect_hits';
        $wpdb->query("TRUNCATE TABLE `{$table_name}`"); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
    }
    
    /**
     * Resolves redirect chains to prevent infinite loops and multiple redirects
     * 
     * @param string $url The URL to resolve
     * @param array $visited Track visited URLs to prevent infinite loops
     * @return string The final destination URL
     */
    private function resolve_redirect_chain($url, $visited = array()) {
        // Prevent infinite loops by limiting depth and tracking visited URLs
        if (count($visited) >= 10 || in_array($url, $visited)) {
            return $url;
        }
        
        $visited[] = $url;
        
        // Check if this URL has a manual redirect
        $manual_redirect = $this->get_manual_redirect($url);
        if ($manual_redirect && $manual_redirect['is_active']) {
            return $this->resolve_redirect_chain($manual_redirect['to_url'], $visited);
        }
        
        // Check if this URL has a cached AI redirect
        $cached_redirect = $this->get_cached_404_redirect($url);
        if ($cached_redirect && $cached_redirect !== $url) {
            return $this->resolve_redirect_chain($cached_redirect, $visited);
        }
        
        return $url;
    }
    
    /**
     * Updates all redirect chains when a URL destination changes
     * This prevents redirect chains from forming when content URLs change
     * 
     * @param string $old_url The old URL that was a destination
     * @param string $new_url The new URL it should point to
     */
    private function update_redirect_chains($old_url, $new_url) {
        global $wpdb;
        
        // Update manual redirects that point to the old URL
        $manual_table = $wpdb->prefix . 'ai_404_manual_redirects';
        $wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            $manual_table,
            array('to_url' => $new_url),
            array('to_url' => $old_url),
            array('%s'),
            array('%s')
        );
        
        // Update 404 hit cache that points to the old URL
        $hits_table = $wpdb->prefix . 'ai_404_redirect_hits';
        $wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
            $hits_table,
            array('redirected_to' => $new_url),
            array('redirected_to' => $old_url),
            array('%s'),
            array('%s')
        );
    }
    
    /**
     * Detects and fixes existing redirect chains in the database
     * This can be run periodically or on-demand to clean up chains
     */
    public function fix_existing_redirect_chains() {
        global $wpdb;
        
        // Get all manual redirects
        $manual_table = $wpdb->prefix . 'ai_404_manual_redirects';
        $redirects = $wpdb->get_results("SELECT * FROM `{$manual_table}` WHERE is_active = 1", ARRAY_A); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
        
        foreach ($redirects as $redirect) {
            $final_destination = $this->resolve_redirect_chain($redirect['to_url']);
            
            // If the final destination is different, update it
            if ($final_destination !== $redirect['to_url']) {
                $wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
                    $manual_table,
                    array('to_url' => $final_destination),
                    array('id' => $redirect['id']),
                    array('%s'),
                    array('%d')
                );
            }
        }
        
        // Get all 404 hit redirects
        $hits_table = $wpdb->prefix . 'ai_404_redirect_hits';
        $hits = $wpdb->get_results("SELECT * FROM `{$hits_table}` WHERE redirected_to IS NOT NULL AND redirected_to != ''", ARRAY_A); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
        
        foreach ($hits as $hit) {
            $final_destination = $this->resolve_redirect_chain($hit['redirected_to']);
            
            // If the final destination is different, update it
            if ($final_destination !== $hit['redirected_to']) {
                $wpdb->update( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
                    $hits_table,
                    array('redirected_to' => $final_destination),
                    array('id' => $hit['id']),
                    array('%s'),
                    array('%d')
                );
            }
        }
    }
    
    /**
     * Handle post URL changes (slug updates, status changes)
     */
    public function handle_post_url_change($post_id, $post_after, $post_before) {
        // Only process published posts and pages
        if ($post_after->post_status !== 'publish' && $post_before->post_status !== 'publish') {
            return;
        }
        
        $old_url = '';
        $new_url = '';
        
        // Get old URL if post was previously published
        if ($post_before->post_status === 'publish') {
            $old_permalink = get_permalink($post_before);
            $old_url = str_replace(home_url(), '', $old_permalink);
        }
        
        // Get new URL if post is now published
        if ($post_after->post_status === 'publish') {
            $new_permalink = get_permalink($post_after);
            $new_url = str_replace(home_url(), '', $new_permalink);
        }
        
        // If URLs changed, update redirect chains
        if (!empty($old_url) && !empty($new_url) && $old_url !== $new_url) {
            $this->update_redirect_chains($old_url, $new_url);
        }
    }
    
    /**
     * Handle taxonomy term URL changes (category, tag slug updates)
     */
    public function handle_term_url_change($term_id, $taxonomy, $args) {
        $term = get_term($term_id, $taxonomy);
        if (!$term || is_wp_error($term)) {
            return;
        }
        
        // Get old term data if available
        if (isset($args['slug'])) {
            $old_slug = $args['slug'];
            $new_slug = $term->slug;
            
            if ($old_slug !== $new_slug) {
                // Construct old and new URLs
                if ($taxonomy === 'category') {
                    $old_url = str_replace(home_url(), '', get_category_link($term_id));
                    $old_url = str_replace($new_slug, $old_slug, $old_url);
                    $new_url = str_replace(home_url(), '', get_category_link($term_id));
                } elseif ($taxonomy === 'post_tag') {
                    $old_url = str_replace(home_url(), '', get_tag_link($term_id));
                    $old_url = str_replace($new_slug, $old_slug, $old_url);
                    $new_url = str_replace(home_url(), '', get_tag_link($term_id));
                } else {
                    $old_url = str_replace(home_url(), '', get_term_link($term_id, $taxonomy));
                    $old_url = str_replace($new_slug, $old_slug, $old_url);
                    $new_url = str_replace(home_url(), '', get_term_link($term_id, $taxonomy));
                }
                
                if (!empty($old_url) && !empty($new_url) && $old_url !== $new_url) {
                    $this->update_redirect_chains($old_url, $new_url);
                }
            }
        }
    }
    
    /**
     * Handle menu item URL changes
     */
    public function handle_menu_url_change($menu_id, $menu_item_db_id, $args) {
        // This is less critical as menu items aren't typically redirect destinations
        // but included for completeness
        if (isset($args['menu-item-url'])) {
            $new_url = $args['menu-item-url'];
            // Get old URL from database if needed
            $old_menu_item = wp_setup_nav_menu_item(get_post($menu_item_db_id));
            if ($old_menu_item && isset($old_menu_item->url)) {
                $old_url = str_replace(home_url(), '', $old_menu_item->url);
                $new_url = str_replace(home_url(), '', $new_url);
                
                if (!empty($old_url) && !empty($new_url) && $old_url !== $new_url) {
                    $this->update_redirect_chains($old_url, $new_url);
                }
            }
        }
    }
}

// Initialize the plugin
AI_404_Redirect::get_instance();