<?php
/**
 * Plugin Name: AI Search
 * Description: Replaces the default search with an intelligent search system.
 * Version: 1.8.0
 * Author: samuelsilvapt
 * License: GPL2
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit; // Exit if accessed directly.
}
require_once plugin_dir_path( __FILE__ ) . 'includes/class-ai-search-service.php';


class AI_Search {

    /**
     * Singleton instance.
     *
     * @var AI_Search|null
     */
    private static $instance = null;

    /**
     * Plugin version.
     */
    const VERSION = '1.8.0';

    /**
     * OpenAI API Key.
     */
    private $api_key;

    /**
     * Threshold for similarity score.
     */
    private $similarity_threshold;

    /**
     * Initialize the plugin.
     */
    private function __construct() {
        $this->api_key = get_option( 'ai_search_api_key', '' );
        $this->similarity_threshold = get_option( 'ai_search_similarity_threshold', 0.5 );
        $this->provider = get_option( 'ai_search_provider', $this->api_key ? 'openai' : 'ai_service' );
        $this->service_token = get_option( 'ai_search_service_token', '' );
        $this->service_client = new AI_Search_Service();

        $this->register_hooks();

    }

    /**
     * Get the singleton instance.
     *
     * @return AI_Search
     */
    public static function get_instance() {
        if ( null === self::$instance ) {
            self::$instance = new self();
        }

        return self::$instance;
    }

    /**
     * Register hooks.
     */
    private function register_hooks() {

        add_action( 'save_post', [ $this, 'generate_embedding' ] );
        add_filter( 'posts_results', [ $this, 'filter_search_results' ], 10, 2 );
        add_action( 'admin_menu', [ $this, 'register_settings_menu' ] );
        add_action( 'admin_post_ai_search_generate_embeddings', [ $this, 'generate_selected_embeddings' ] );
        add_action( 'admin_post_ai_search_clear_cache', [ $this, 'clear_embeddings_cache' ] );
        add_action( 'admin_post_ai_search_validate_token', [ $this, 'validate_service_token' ] );
        add_action( 'wp_ajax_ai_search_validate_token', [ $this, 'validate_service_token' ] );

    }

    /**
     * Generate embedding for a post and save it to post meta.
     *
     * @param int $post_id Post ID.
     */
    public function generate_embedding( $post_id ) {
        if ( wp_is_post_revision( $post_id ) ) {
            return;
        }

        $post = get_post( $post_id );
        if ( 'publish' !== $post->post_status ) {
            return;
        }

        // Sanitize post title and content
        $post_title = sanitize_text_field( $post->post_title );
        $post_content = sanitize_textarea_field( $post->post_content );

        // Combine context with content for embedding
        $content = $post_title . ' ' . $post_content;
        $embedding = $this->get_embedding( $content );

        if ( $embedding ) {
            update_post_meta( $post_id, '_ai_search_embedding', wp_json_encode( $embedding ) );
        }
    }

    /**
     * Get embedding from OpenAI.
     *
     * @param string $content Content to embed.
     *
     * @return array|false Embedding data or false on failure.
     */
    private function get_embedding( $content ) {
        $content = sanitize_textarea_field( $content );
        // Check for Cached Embedding
        $cached_embedding = get_transient( 'ai_search_embedding_' . md5( $content ) );
        if ( $cached_embedding ) {
            return $cached_embedding;
        }

        if ( $this->provider === 'ai_service' ) {
            // Check if we have a service token first
            $service_token = get_option( 'ai_search_service_token', '' );
            if ( empty( $service_token ) ) {
                return false; // No token available, service not registered
            }
            
            $embedding = $this->service_client->get_embedding( $content );
            if ( $embedding && ! empty( $embedding['embedding']) ) {
                return $embedding['embedding'];
            }
            return false; // Service failed, don't fallback to OpenAI without user consent
        }

        $response = wp_remote_post( 'https://api.openai.com/v1/embeddings', [
            'headers' => [
                'Authorization' => 'Bearer ' . $this->api_key,
                'Content-Type'  => 'application/json',
            ],
            'body'    => wp_json_encode([
                'input' => $content,
                'model' => 'text-embedding-ada-002',
            ]),
        ]);

        if ( is_wp_error( $response ) ) {
            return false;
        }

        $body = json_decode( wp_remote_retrieve_body( $response ), true );

        if ( ! isset( $body['data'][0]['embedding'] ) ) {
            return false;
        }

        // Cache the embedding for 1 day
        set_transient( 'ai_search_embedding_' . md5( $content ), $body['data'][0]['embedding'], MONTH_IN_SECONDS );
        return $body['data'][0]['embedding'];
    }

    /**
     * Customize the search query.
     *
     * @param string $sql Original SQL query.
     * @param WP_Query $query WP_Query object.
     *
     * @return string Modified SQL query.
     */
    public function filter_search_results( $posts, $query ) {
        if ( ! $query->is_search() || is_admin() ) {
            return $posts;
        }

        $post_type = $query->get( 'post_type' );
    
        $search_query = get_search_query();
        $search_query = sanitize_text_field( $search_query );
        $query_embedding = $this->get_embedding( $search_query );
    
        if ( ! $query_embedding ) {
            return $posts;
        }
    
        $similarities = [];

        $all_posts = get_posts([
            'numberposts' => -1,
            'post_type'   => $post_type,
            'post_status' => 'publish',
            'meta_key'    => '_ai_search_embedding',
        ]);

        
        foreach ( $all_posts as $post ) {

            $embedding_json = get_post_meta( $post->ID, '_ai_search_embedding', true );
            if ( empty( $embedding_json ) ) {
                continue;
            }

            $embedding = json_decode( $embedding_json, true );
            if ( ! empty( $embedding['embedding'] ) ) {
                $embedding = $embedding['embedding'];
            }
            $similarity = $this->calculate_similarity( $query_embedding, $embedding );
            if ( $similarity >= $this->similarity_threshold ) {
                $similarities[ $post->ID ] = $similarity;
            }
        }

        if ( empty( $similarities ) ) {
            return $posts; 
        }
    
        arsort( $similarities );
        $ordered_ids = array_keys( $similarities );

        $posts = get_posts([
            'post_type'      => $post_type,
            'post_status'    => 'publish',
            'post__in'       => $ordered_ids,
            'orderby'        => 'post__in',
            'posts_per_page' => -1,
        ]);
        
        return $posts;
    }

    /**
     * Calculate cosine similarity.
     *
     * @param array $a First vector.
     * @param array $b Second vector.
     *
     * @return float Cosine similarity.
     */
   private function calculate_similarity( $a, $b ) {

        if ( ! is_array( $a ) || ! is_array( $b ) || count( $a ) !== count( $b ) ) {
            return 0;
        }

        $dot_product = array_sum( array_map( function ( $x, $y ) {
            return $x * $y;
        }, $a, $b ) );

        $magnitude_a = sqrt( array_sum( array_map( function ( $x ) {
            return $x ** 2;
        }, $a ) ) );

        $magnitude_b = sqrt( array_sum( array_map( function ( $x ) {
            return $x ** 2;
        }, $b ) ) );

        if ( $magnitude_a === 0 || $magnitude_b === 0 ) {
            return 0;
        }

        return $dot_product / ( $magnitude_a * $magnitude_b );
    }


    /**
     * Register settings menu in admin.
     */
    public function register_settings_menu() {
        add_options_page(
            'AI Search Settings',
            'AI Search',
            'manage_options',
            'ai-search',
            [ $this, 'settings_page' ]
        );
    }

    /**
     * Check if AI service registration is needed and attempt registration.
     *
     * @param string $provider The selected provider.
     * @return array Result array with 'success' boolean and 'message' string.
     */
    private function handle_ai_service_registration( $provider ) {
        if ( $provider !== 'ai_service' ) {
            return [ 'success' => true, 'message' => 'Settings saved successfully!' ];
        }

        if ( ! empty( get_option( 'ai_search_service_token', '' ) ) ) {
            return [ 'success' => true, 'message' => 'Settings saved successfully!' ];
        }

        return $this->attempt_service_registration();
    }

    /**
     * Attempt to register with AI service and handle the response.
     *
     * @return array Result array with 'success' boolean and 'message' string.
     */
    private function attempt_service_registration() {
        $service_token = $this->service_client->register_origin();
        
        if ( $service_token ) {
            update_option( 'ai_search_service_token', $service_token );
            return [ 
                'success' => true, 
                'message' => 'Settings saved successfully! AI Search Service registered.' 
            ];
        }

        return [ 
            'success' => false, 
            'message' => '<strong>AI Search Service is temporarily unavailable.</strong> Please try again later or use your own OpenAI API key instead.' 
        ];
    }

    /**
     * Display registration result message.
     *
     * @param array $result Result from registration attempt.
     */
    private function display_registration_message( $result ) {
        $class = $result['success'] ? 'updated' : 'error';
        echo '<div class="' . $class . '"><p>' . $result['message'] . '</p></div>';
    }

    /**
     * Generate embedding for selected custom post type.
     * @return void
     */
    public function generate_selected_embeddings() {
        if ( ! current_user_can( 'manage_options' ) || ! isset( $_POST['cpt'] ) ) {
            wp_die( __( 'Unauthorized access', 'ai-search' ) );
        }

        $cpt = sanitize_text_field( $_POST['cpt'] );
        $limit = isset( $_POST['limit'] ) ? intval( $_POST['limit'] ) : 50;
        $limit = min( max( $limit, 1 ), 1000 ); // Sanitize: min 1, max 1000
        $processed_titles = [];

        $posts = get_posts([
            'numberposts' => $limit,
            'post_type'   => $cpt,
            'post_status' => 'publish',
            'meta_query'  => [
                [
                    'key'     => '_ai_search_embedding',
                    'compare' => 'NOT EXISTS'
                ]
            ]
        ]);

        foreach ( $posts as $post ) {
            $this->generate_embedding( $post->ID );
            $processed_titles[] = $post->post_title;
        }

        set_transient( 'ai_search_processed_titles', $processed_titles, MINUTE_IN_SECONDS );

        wp_redirect( admin_url( 'options-general.php?page=ai-search&embeddings_generated=true&tab=embeddings' ) );
        exit;
    }

    /**
     * Clear all embedding cache (transients and post meta).
     * @return void
     */
    public function clear_embeddings_cache() {
        if ( ! current_user_can( 'manage_options' ) ) {
            wp_die( __( 'Unauthorized access', 'ai-search' ) );
        }

        check_admin_referer( 'ai_search_clear_cache' );

        $cache_type = isset( $_POST['cache_type'] ) ? sanitize_text_field( $_POST['cache_type'] ) : 'transients';
        $cleared_count = 0;

        if ( $cache_type === 'transients' || $cache_type === 'all' ) {
            // Clear embedding transients
            $cleared_count += $this->clear_embedding_transients();
        }

        if ( $cache_type === 'post_meta' || $cache_type === 'all' ) {
            // Clear post meta embeddings
            $cleared_count += $this->clear_post_meta_embeddings();
        }

        $message = $cache_type === 'all' ? 'all_cache_cleared' : $cache_type . '_cleared';
        wp_redirect( admin_url( 'options-general.php?page=ai-search&cache_cleared=' . $message . '&count=' . $cleared_count . '&tab=cache' ) );
        exit;
    }

    /**
     * Validate the service token via admin action.
     * @return void
     */
    public function validate_service_token() {
        if ( ! current_user_can( 'manage_options' ) ) {
            wp_die( __( 'Unauthorized access', 'ai-search' ) );
        }

        check_admin_referer( 'ai_search_validate_token' );

        // Check if token exists first
        $service_token = get_option( 'ai_search_service_token', '' );
        if ( empty( $service_token ) ) {
            wp_redirect( admin_url( 'options-general.php?page=ai-search&token_validation=no_token&tab=general' ) );
            exit;
        }

        $validation_result = $this->service_client->validate_token();
        
        if ( $validation_result === false ) {
            wp_redirect( admin_url( 'options-general.php?page=ai-search&token_validation=error&tab=general' ) );
        } elseif ( isset( $validation_result['valid'] ) && $validation_result['valid'] === true ) {
            // Store validation data in transient for display
            set_transient( 'ai_search_validation_data', $validation_result, 300 ); // 5 minutes
            wp_redirect( admin_url( 'options-general.php?page=ai-search&token_validation=success&tab=general' ) );
        } else {
            // Invalid token
            set_transient( 'ai_search_validation_error', $validation_result, 300 ); // 5 minutes
            wp_redirect( admin_url( 'options-general.php?page=ai-search&token_validation=invalid&tab=general' ) );
        }
        
        exit;
    }

    /**
     * Clear embedding transients from WordPress cache.
     * @return int Number of transients cleared.
     */
    private function clear_embedding_transients() {
        global $wpdb;
        
        // Clear ai_search_embedding_ transients
        $result = $wpdb->query( 
            $wpdb->prepare( 
                "DELETE FROM {$wpdb->options} WHERE option_name LIKE %s OR option_name LIKE %s",
                '_transient_ai_search_embedding_%',
                '_transient_timeout_ai_search_embedding_%'
            )
        );

        // Also clear ai_service_embedding_ transients
        $result += $wpdb->query( 
            $wpdb->prepare( 
                "DELETE FROM {$wpdb->options} WHERE option_name LIKE %s OR option_name LIKE %s",
                '_transient_ai_service_embedding_%',
                '_transient_timeout_ai_service_embedding_%'
            )
        );

        return $result;
    }

    /**
     * Clear post meta embeddings.
     * @return int Number of post meta entries cleared.
     */
    private function clear_post_meta_embeddings() {
        global $wpdb;
        
        $result = $wpdb->query( 
            $wpdb->prepare( 
                "DELETE FROM {$wpdb->postmeta} WHERE meta_key = %s",
                '_ai_search_embedding'
            )
        );

        return $result;
    }


    /**
     * Display settings page.
     */
    /**
     * Display settings page with tabs.
     */
    public function settings_page() {
        $active_tab = isset( $_GET['tab'] ) ? sanitize_text_field( $_GET['tab'] ) : 'general';

        echo '<div class="wrap">';
        echo '<h1>AI Search Settings</h1>';
        echo '<h2 class="nav-tab-wrapper">';
        echo '<a href="?page=ai-search&tab=general" class="nav-tab ' . ( $active_tab == 'general' ? 'nav-tab-active' : '' ) . '">General Settings</a>';
        echo '<a href="?page=ai-search&tab=embeddings" class="nav-tab ' . ( $active_tab == 'embeddings' ? 'nav-tab-active' : '' ) . '">Generate Embeddings</a>';
        echo '<a href="?page=ai-search&tab=cache" class="nav-tab ' . ( $active_tab == 'cache' ? 'nav-tab-active' : '' ) . '">Cache Management</a>';
        echo '</h2>';

        if ( $active_tab == 'general' ) {
            $this->general_settings_page();
        } elseif ( $active_tab == 'embeddings' ) {
            $this->embeddings_settings_page();
        } else {
            $this->cache_management_page();
        }

        echo '</div>';
    }


    /**
     * General settings tab.
     */
    private function general_settings_page() {
        // Handle token validation messages
        if ( isset( $_GET['token_validation'] ) ) {
            $validation_status = sanitize_text_field( $_GET['token_validation'] );
            
            if ( $validation_status === 'success' ) {
                $validation_data = get_transient( 'ai_search_validation_data' );
                if ( $validation_data ) {
                    echo '<div class="updated"><p><strong>Token Validation Successful!</strong></p>';
                    if ( isset( $validation_data['client'] ) ) {
                        $client = $validation_data['client'];
                        echo '<ul style="margin-left: 20px;">';
                        echo '<li><strong>Client ID:</strong> ' . esc_html( $client['id'] ?? 'N/A' ) . '</li>';
                        echo '<li><strong>Origin:</strong> ' . esc_html( $client['origin'] ?? 'N/A' ) . '</li>';
                        echo '<li><strong>Daily Limit:</strong> ' . esc_html( number_format( $client['daily_limit'] ?? 0 ) ) . '</li>';
                        echo '<li><strong>Total Limit:</strong> ' . esc_html( number_format( $client['total_limit'] ?? 0 ) ) . '</li>';
                        echo '<li><strong>Used Daily:</strong> ' . esc_html( number_format( $client['used_daily'] ?? 0 ) ) . '</li>';
                        echo '<li><strong>Used Total:</strong> ' . esc_html( number_format( $client['used_total'] ?? 0 ) ) . '</li>';
                        echo '<li><strong>Quotas Exceeded:</strong> ' . ( 
                            isset( $client['quotas_exceeded']['daily'] ) && $client['quotas_exceeded']['daily'] ? 'Daily' : '' 
                        ) . ( 
                            isset( $client['quotas_exceeded']['total'] ) && $client['quotas_exceeded']['total'] ? ' Total' : '' 
                        ) . ( 
                            !( $client['quotas_exceeded']['daily'] ?? false ) && !( $client['quotas_exceeded']['total'] ?? false ) ? 'None' : '' 
                        ) . '</li>';
                        echo '</ul>';
                    }
                    echo '</div>';
                    delete_transient( 'ai_search_validation_data' );
                }
            } elseif ( $validation_status === 'invalid' ) {
                $error_data = get_transient( 'ai_search_validation_error' );
                echo '<div class="error"><p><strong>Token Validation Failed!</strong></p>';
                if ( $error_data && isset( $error_data['details'] ) ) {
                    echo '<p>Error: ' . esc_html( $error_data['details'] ) . '</p>';
                }
                echo '</div>';
                delete_transient( 'ai_search_validation_error' );
            } elseif ( $validation_status === 'error' ) {
                echo '<div class="error"><p><strong>Token Validation Error!</strong> Unable to connect to AI Search Service.</p></div>';
            } elseif ( $validation_status === 'no_token' ) {
                echo '<div class="error"><p><strong>No Token Found!</strong> Please save your settings first to generate a service token.</p></div>';
            }
        }

        if ( isset( $_POST['provider'], $_POST['api_key'], $_POST['similarity_threshold'] ) ) {
            check_admin_referer( 'ai_search_save_settings' );
            
            $new_provider = sanitize_text_field( $_POST['provider'] );
            $current_provider = get_option( 'ai_search_provider', '' );
            
            // Save the basic settings
            update_option( 'ai_search_provider', $new_provider );
            update_option( 'ai_search_api_key', sanitize_text_field( wp_unslash( $_POST['api_key'] ) ) );
            update_option( 'ai_search_similarity_threshold', floatval( $_POST['similarity_threshold'] ) );
            
            // Save service token if provided
            if ( isset( $_POST['service_token'] ) ) {
                update_option( 'ai_search_service_token', sanitize_text_field( wp_unslash( $_POST['service_token'] ) ) );
            }
            
            // Handle AI service registration
            $registration_result = $this->handle_ai_service_registration( $new_provider );
            
            if ( ! $registration_result['success'] ) {
                // Registration failed - revert provider setting
                update_option( 'ai_search_provider', $current_provider );
            }
            
            // Display the result message
            $this->display_registration_message( $registration_result );
        }

        $provider = get_option( 'ai_search_provider', $this->api_key ? 'openai' : 'ai_service' );
        $api_key = get_option( 'ai_search_api_key', '' );
        $service_token = get_option( 'ai_search_service_token', '' );
        $similarity_threshold = get_option( 'ai_search_similarity_threshold', 0.5 );

        echo '<form method="post" action="">';
        wp_nonce_field( 'ai_search_save_settings' );

        echo '<label for="provider"><strong>AI Provider:</strong></label><br>';
        echo '<select id="provider" name="provider" onchange="aiSearchToggleApiKey()">';
        echo '<option value="ai_service"' . selected( $provider, 'ai_service', false ) . '>AI Search Service (Free up to 10,000 embeddings/site)</option>';
        echo '<option value="openai"' . selected( $provider, 'openai', false ) . '>Use your own OpenAI API Key</option>';
        echo '</select>';
        echo '<p><em>Choose between using our external service (no API key needed) or managing embeddings yourself with an OpenAI key. No personal data is stored or used for other purposes.</em></p>';

        echo '<br/><br/>';

        echo '<div id="openai-key-container" style="display: ' . ( $provider === 'openai' ? 'block' : 'none' ) . ';">';
        echo '<label for="api_key">OpenAI API Key:</label><br>';
        echo '<input type="text" id="api_key" name="api_key" value="' . esc_attr( $api_key ) . '" style="width: 100%; max-width: 400px;" />';
        echo '</div>';

        echo '<div id="service-token-container" style="display: ' . ( $provider === 'ai_service' ? 'block' : 'none' ) . ';">';
        echo '<label for="service_token">AI Search Service Token:</label><br>';
        echo '<input type="text" id="service_token" name="service_token" value="' . esc_attr( $service_token ) . '" style="width: 100%; max-width: 400px;" />';
        echo '<p><em>This token is automatically generated when you select the AI Service. You can manually update it if needed.</em></p>';
        
        // Add validation button if token exists
        if ( ! empty( $service_token ) ) {
            echo '<div style="margin-top: 10px;">';
            echo '<button type="button" id="validate-token-btn" class="button button-secondary">Validate Token</button>';
            echo '<span id="validation-spinner" style="display: none; margin-left: 10px;">Validating...</span>';
            echo '<p><em>Click to validate your token and check usage statistics.</em></p>';
            echo '</div>';
        }
        
        echo '</div>';

        echo '<br/><br/>';

        echo '<label for="similarity_threshold">Similarity Threshold (0.5-1):</label><br>';
        echo '<input type="range" id="similarity_threshold" name="similarity_threshold" min="0.5" max="1" step="0.001" value="' . esc_attr( $similarity_threshold ) . '" oninput="this.nextElementSibling.value = Number(this.value).toFixed(3)">';
        echo '<output>' . number_format( $similarity_threshold, 3 ) . '</output>';
        echo '<p><em>Defines how similar a post must be to appear in search results. Higher values (closer to 1.0) mean stricter, more relevant results. Values below 0.5 often return too many irrelevant matches. Default: 0.500.</em></p>';

        echo '<br/><br/>';
        echo '<input type="submit" class="button-primary" value="Save Settings" />';
        echo '</form>';

        echo '<script>
        function aiSearchToggleApiKey() {
            var provider = document.getElementById("provider").value;
            document.getElementById("openai-key-container").style.display = (provider === "openai") ? "block" : "none";
            document.getElementById("service-token-container").style.display = (provider === "ai_service") ? "block" : "none";
        }
        
        document.addEventListener("DOMContentLoaded", function() {
            var validateBtn = document.getElementById("validate-token-btn");
            if (validateBtn) {
                validateBtn.addEventListener("click", function() {
                    var spinner = document.getElementById("validation-spinner");
                    validateBtn.disabled = true;
                    spinner.style.display = "inline";
                    
                    // Create a form and submit it
                    var form = document.createElement("form");
                    form.method = "POST";
                    form.action = "' . esc_url( admin_url( 'admin-post.php?action=ai_search_validate_token' ) ) . '";
                    
                    var nonceField = document.createElement("input");
                    nonceField.type = "hidden";
                    nonceField.name = "_wpnonce";
                    nonceField.value = "' . wp_create_nonce( 'ai_search_validate_token' ) . '";
                    
                    form.appendChild(nonceField);
                    document.body.appendChild(form);
                    form.submit();
                });
            }
        });
        </script>';
    }


    /**
     * Embeddings settings tab.
     */
    private function embeddings_settings_page() {
        if ( isset( $_GET['embeddings_generated'] ) ) {
            echo '<div class="updated"><p>Embeddings have been generated for selected posts!</p></div>';
            $processed_titles = get_transient( 'ai_search_processed_titles' );
            if ( $processed_titles && is_array( $processed_titles ) ) {
                echo '<div class="updated"><p>Embeddings have been generated for the following posts:</p><ul>';
                foreach ( $processed_titles as $title ) {
                    echo '<li>' . esc_html( $title ) . '</li>';
                }
                echo '</ul></div>';
                delete_transient( 'ai_search_processed_titles' );
            }

        }

        $post_types = get_post_types( [ 'public' => true ], 'objects' );
        echo '<h2>Generate Embeddings for Selected CPT</h2>';
        echo '<p>Select a custom post type and click the button to generate embeddings for posts that do not yet have them.</p>';
        echo '<form method="post" action="' . esc_url( admin_url( 'admin-post.php?action=ai_search_generate_embeddings' ) ) . '">';
        echo '<label for="cpt">Select Custom Post Type:</label><br>';
        echo '<select name="cpt" id="cpt">';
        foreach ( $post_types as $post_type ) {
            echo '<option value="' . esc_attr( $post_type->name ) . '">' . esc_html( $post_type->label ) . '</option>';
        }
        echo '</select><br><br>';

        echo '<label for="limit">How many posts?</label><br>';
        echo '<select name="limit" id="limit">';
        foreach ( [50, 100, 200, 400, 600, 1000] as $count ) {
            echo '<option value="' . $count . '">' . $count . '</option>';
        }
        echo '</select>';
        echo '<p><strong>Note:</strong> Selecting higher values (e.g., 400 or more) may cause timeouts or crash the server depending on your hosting limits. Use with caution.</p><br><br>';

        echo '<input type="submit" class="button button-secondary" value="Generate Embeddings" />';
        echo '</form>';

    }

    /**
     * Cache management tab.
     */
    private function cache_management_page() {
        // Display success messages
        if ( isset( $_GET['cache_cleared'] ) ) {
            $cleared_type = sanitize_text_field( $_GET['cache_cleared'] );
            $count = isset( $_GET['count'] ) ? intval( $_GET['count'] ) : 0;
            
            $messages = [
                'transients_cleared' => 'Embedding cache (transients) cleared successfully!',
                'post_meta_cleared' => 'Post meta embeddings cleared successfully!',
                'all_cache_cleared' => 'All embedding cache and post meta cleared successfully!'
            ];
            
            $message = isset( $messages[$cleared_type] ) ? $messages[$cleared_type] : 'Cache cleared successfully!';
            echo '<div class="updated"><p>' . $message . ' (' . $count . ' entries removed)</p></div>';
        }

        echo '<h2>Cache Management</h2>';
        echo '<p>Manage your AI Search embedding cache. Use these options to clear cached embeddings when needed.</p>';

        // Get cache statistics
        $stats = $this->get_cache_statistics();
        
        echo '<div class="cache-stats" style="background: #f1f1f1; padding: 15px; margin: 20px 0; border-radius: 5px;">';
        echo '<h3>Cache Statistics</h3>';
        echo '<p><strong>Cached Embeddings (Transients):</strong> ~' . $stats['transients'] . ' entries</p>';
        echo '<p><strong>Post Meta Embeddings:</strong> ' . $stats['post_meta'] . ' posts</p>';
        echo '<p><em>Note: Transient count is approximate and includes both embedding cache and timeout entries.</em></p>';
        echo '</div>';

        echo '<div class="cache-actions">';
        
        // Clear transients only
        echo '<div style="margin-bottom: 20px; padding: 15px; border: 1px solid #ddd; border-radius: 5px;">';
        echo '<h3>Clear Embedding Cache (Transients)</h3>';
        echo '<p>Clears temporarily cached embeddings. These will be regenerated automatically when needed.</p>';
        echo '<form method="post" action="' . esc_url( admin_url( 'admin-post.php?action=ai_search_clear_cache' ) ) . '" style="display: inline;">';
        wp_nonce_field( 'ai_search_clear_cache' );
        echo '<input type="hidden" name="cache_type" value="transients" />';
        echo '<input type="submit" class="button button-secondary" value="Clear Cache Only" onclick="return confirm(\'Are you sure you want to clear the embedding cache?\');" />';
        echo '</form>';
        echo '</div>';

        // Clear post meta embeddings
        echo '<div style="margin-bottom: 20px; padding: 15px; border: 1px solid #ddd; border-radius: 5px;">';
        echo '<h3>Clear Post Embeddings</h3>';
        echo '<p><strong>Warning:</strong> This will remove stored embeddings from all posts. You will need to regenerate them manually.</p>';
        echo '<form method="post" action="' . esc_url( admin_url( 'admin-post.php?action=ai_search_clear_cache' ) ) . '" style="display: inline;">';
        wp_nonce_field( 'ai_search_clear_cache' );
        echo '<input type="hidden" name="cache_type" value="post_meta" />';
        echo '<input type="submit" class="button button-secondary" value="Clear Post Embeddings" onclick="return confirm(\'WARNING: This will remove all stored post embeddings. You will need to regenerate them. Continue?\');" />';
        echo '</form>';
        echo '</div>';

        // Clear everything
        echo '<div style="margin-bottom: 20px; padding: 15px; border: 1px solid #e74c3c; border-radius: 5px; background: #fdf2f2;">';
        echo '<h3 style="color: #e74c3c;">Clear All Embedding Data</h3>';
        echo '<p><strong>DANGER:</strong> This will remove ALL embedding cache and post meta. AI Search will stop working until you regenerate embeddings.</p>';
        echo '<form method="post" action="' . esc_url( admin_url( 'admin-post.php?action=ai_search_clear_cache' ) ) . '" style="display: inline;">';
        wp_nonce_field( 'ai_search_clear_cache' );
        echo '<input type="hidden" name="cache_type" value="all" />';
        echo '<input type="submit" class="button button-secondary" value="Clear Everything" onclick="return confirm(\'DANGER: This will remove ALL embedding data. AI Search will stop working until you regenerate embeddings. Are you absolutely sure?\');" style="background: #e74c3c; border-color: #c0392b; color: white;" />';
        echo '</form>';
        echo '</div>';

        echo '</div>';
    }

    /**
     * Get cache statistics.
     * @return array Cache statistics.
     */
    private function get_cache_statistics() {
        global $wpdb;
        
        // Count embedding-related transients (approximate)
        $transients = $wpdb->get_var( 
            $wpdb->prepare( 
                "SELECT COUNT(*) FROM {$wpdb->options} WHERE option_name LIKE %s OR option_name LIKE %s",
                '_transient_ai_search_embedding_%',
                '_transient_ai_service_embedding_%'
            )
        );

        // Count posts with embeddings
        $post_meta = $wpdb->get_var( 
            $wpdb->prepare( 
                "SELECT COUNT(*) FROM {$wpdb->postmeta} WHERE meta_key = %s",
                '_ai_search_embedding'
            )
        );

        return [
            'transients' => intval( $transients ),
            'post_meta' => intval( $post_meta )
        ];
    }


}

// Initialize the plugin.
AI_Search::get_instance();