<?php
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

class ACOSMAIA_Chat_Handler {
    private $product_finder;

    private $last_product_meta = [
        'has_more'      => false,
        'show_more_url' => '',
    ];

    public function permission_check( WP_REST_Request $request ) {
        unset( $request );
        // Public storefront endpoint. Request safety is enforced in handle()
        // via input sanitization, rate limiting, and model usage limits.
        return __return_true();
    }

    public function handle( WP_REST_Request $request ) {
        $debug_id = function_exists( 'wp_generate_uuid4' ) ? wp_generate_uuid4() : uniqid( 'acosmaia_', true );
        $this->last_product_meta = [
            'has_more'      => false,
            'show_more_url' => '',
        ];
        
        if ( ! class_exists( 'WooCommerce' ) ) {
            $this->report_error_event( $debug_id, 'woocommerce_missing', 'WooCommerce is required.' );
            return new WP_REST_Response( [ 'error' => 'WooCommerce is required.' ], 500 );
        }

        if ( ! $this->allow_request_rate() ) {
            return new WP_REST_Response( [ 'error' => 'Too many requests. Please wait a minute and try again.' ], 429 );
        }

        $message = sanitize_text_field( (string) $request->get_param( 'message' ) );
        if ( $message === '' ) {
            return new WP_REST_Response( [ 'error' => 'Message is required.' ], 400 );
        }

        $message_lower = strtolower( $message );

        if ( $this->is_order_details_request( $message_lower ) ) {
            $order_details_message = $this->build_current_user_order_details_message();
            $this->increment_counter( 'acosmaia_total_chats' );

            return new WP_REST_Response( [
                'message'         => $order_details_message,
                'warning'         => '',
                'products'        => [],
                'show_more_url'   => '',
                'show_more_label' => '',
                'applied_filters' => [],
                'total_found'     => 0,
                'debug_id'        => $debug_id,
                'usage'           => [ 'total_tokens' => 0 ],
            ], 200 );
        }

        $access_warning = $this->get_blocking_access_warning( $message_lower );

        if ( '' !== $access_warning ) {
            $this->increment_counter( 'acosmaia_total_chats' );

            return new WP_REST_Response( [
                'message'       => $access_warning,
                'warning'       => $access_warning,
                'products'      => [],
                'show_more_url' => '',
                'show_more_label' => '',
                'applied_filters' => [],
                'total_found'   => 0,
                'debug_id'      => $debug_id,
                'usage'         => [ 'total_tokens' => 0 ],
            ], 200 );
        }

        $page_access_warning = $this->get_page_access_warning( $message_lower );

        // Check if API is configured
        $ai_client = ACOSMAIA_AI_API_Client::from_settings();
        $is_api_configured = $ai_client->is_configured();

        if ( ! $this->usage_limit_available() && $is_api_configured ) {
            $limit_message = $this->get_token_finished_message();
            return new WP_REST_Response( [
                'message' => $limit_message,
                'warning' => $limit_message,
                'error'   => $limit_message,
            ], 429 );
        }

        $query_plan = [];
        if ( $is_api_configured && $this->should_plan_product_query( $message_lower ) ) {
            $query_plan = $this->generate_product_query_plan( '', $message );
        }

        $finder_result = $this->get_product_finder()->find( $message, $query_plan );
        if ( ! is_array( $finder_result ) ) {
            $this->increment_counter( 'acosmaia_failed_queries' );
            $this->report_error_event( $debug_id, 'product_finder_invalid_result', 'Product finder returned an invalid result.' );

            return new WP_REST_Response( [
                'message'  => get_option( 'acosmaia_fallback_response', 'Sorry, I am unable to answer right now. Please contact support.' ),
                'warning'  => $page_access_warning,
                'products' => [],
                'show_more_url' => '',
                'show_more_label' => '',
                'applied_filters' => [],
                'total_found' => 0,
                'debug_id' => $debug_id,
                'error'    => 'Invalid product finder response.',
            ], 200 );
        }

        $products = isset( $finder_result['products'] ) && is_array( $finder_result['products'] )
            ? $finder_result['products']
            : [];
        $product_cards = $this->build_product_cards( $products );
        $show_more_url = isset( $finder_result['show_more_url'] ) ? (string) $finder_result['show_more_url'] : '';
        $show_more_label = $show_more_url ? 'Show more products' : '';
        $total_found = isset( $finder_result['total_found'] ) ? (int) $finder_result['total_found'] : count( $products );
        $applied_filters = isset( $finder_result['applied_filters'] ) && is_array( $finder_result['applied_filters'] )
            ? $finder_result['applied_filters']
            : [];

        $this->increment_counter( 'acosmaia_total_chats' );

        if ( ! $is_api_configured ) {
            return new WP_REST_Response( [
                'message'  => $this->fallback_message( $products, $message, true ),
                'warning'  => $page_access_warning,
                'products' => $product_cards,
                'show_more_url' => $show_more_url,
                'show_more_label' => $show_more_label,
                'applied_filters' => $applied_filters,
                'total_found' => $total_found,
                'debug_id' => $debug_id,
                'usage'    => [ 'total_tokens' => 0 ],
            ], 200 );
        }

        $system_prompt = $this->build_system_prompt( $products, $message );

        if ( ! $ai_client->is_configured() ) {
            return new WP_REST_Response( [
                'message'  => $this->fallback_message( $products, $message, true ),
                'warning'  => $page_access_warning,
                'products' => $product_cards,
                'show_more_url' => $show_more_url,
                'show_more_label' => $show_more_label,
                'applied_filters' => $applied_filters,
                'total_found' => $total_found,
                'debug_id' => $debug_id,
                'usage'    => [ 'total_tokens' => 0 ],
            ], 200 );
        }

        $request_response = $ai_client->request( $system_prompt, $message );

        if ( is_wp_error( $request_response ) ) {
            $this->increment_counter( 'acosmaia_failed_queries' );
            $error_message = (string) $request_response->get_error_message();
            $this->report_error_event( $debug_id, 'ai_request_error', $error_message );
            
            $is_token_limit = $this->is_token_limit_error_message( $error_message );
            $assistant_message = $is_token_limit
                ? $this->get_token_finished_message()
                : get_option( 'acosmaia_fallback_response', 'Sorry, I am unable to answer right now. Please contact support.' );

            return new WP_REST_Response( [
                'message'  => $assistant_message,
                'warning'  => $is_token_limit ? $assistant_message : $page_access_warning,
                'products' => $product_cards,
                'show_more_url' => $show_more_url,
                'show_more_label' => $show_more_label,
                'applied_filters' => $applied_filters,
                'total_found' => $total_found,
                'debug_id' => $debug_id,
                'error'    => $error_message,
            ], 200 );
        }

        $parsed = $ai_client->parse_response( $request_response );

        if ( isset( $parsed['error'] ) ) {
            $this->increment_counter( 'acosmaia_failed_queries' );
            $error_message = (string) $parsed['error'];
            $this->report_error_event( $debug_id, 'ai_parse_error', $error_message );
            
            $is_token_limit = $this->is_token_limit_error_message( $error_message );
            $assistant_message = $is_token_limit
                ? $this->get_token_finished_message()
                : get_option( 'acosmaia_fallback_response', 'Sorry, I am unable to answer right now. Please contact support.' );

            return new WP_REST_Response( [
                'message'  => $assistant_message,
                'warning'  => $is_token_limit ? $assistant_message : $page_access_warning,
                'products' => $product_cards,
                'show_more_url' => $show_more_url,
                'show_more_label' => $show_more_label,
                'applied_filters' => $applied_filters,
                'total_found' => $total_found,
                'debug_id' => $debug_id,
                'error'    => $error_message,
            ], 200 );
        }

        $ai_content = isset( $parsed['content'] ) ? $parsed['content'] : '';
        $ai_usage = isset( $parsed['usage'] ) ? $parsed['usage'] : [];
        $assistant_message = trim( wp_strip_all_tags( (string) $ai_content ) );

        if ( ! empty( $product_cards ) ) {
            $assistant_message = 'Here are some products that match your search.';
        }

        if ( empty( $ai_content ) ) {
            $this->increment_counter( 'acosmaia_failed_queries' );
            $provider_error = 'Unexpected AI response: empty content.';
            $this->report_error_event( $debug_id, 'ai_empty_content', $provider_error );
            $is_token_limit = $this->is_token_limit_error_message( $provider_error );
            $assistant_message = $is_token_limit
                ? $this->get_token_finished_message()
                : get_option( 'acosmaia_fallback_response', 'Sorry, I am unable to answer right now. Please contact support.' );

            return new WP_REST_Response( [
                'message'  => $assistant_message,
                'warning'  => $is_token_limit ? $assistant_message : $page_access_warning,
                'products' => $product_cards,
                'show_more_url' => $show_more_url,
                'show_more_label' => $show_more_label,
                'applied_filters' => $applied_filters,
                'total_found' => $total_found,
                'debug_id' => $debug_id,
                'error'    => $provider_error,
            ], 200 );
        }

        $this->track_usage( $ai_usage );

        return new WP_REST_Response( [
            'message'  => $assistant_message,
            'warning'  => $page_access_warning,
            'products' => $product_cards,
            'show_more_url' => $show_more_url,
            'show_more_label' => $show_more_label,
            'applied_filters' => $applied_filters,
            'total_found' => $total_found,
            'debug_id' => $debug_id,
            'usage'    => [
                'prompt_tokens'     => isset( $ai_usage['prompt_tokens'] ) ? (int) $ai_usage['prompt_tokens'] : 0,
                'completion_tokens' => isset( $ai_usage['completion_tokens'] ) ? (int) $ai_usage['completion_tokens'] : 0,
                'total_tokens'      => isset( $ai_usage['total_tokens'] ) ? (int) $ai_usage['total_tokens'] : 0,
            ],
        ], 200 );
    }

    private function get_product_finder() {
        if ( ! $this->product_finder instanceof ACOSMAIA_Product_Finder ) {
            $this->product_finder = new ACOSMAIA_Product_Finder();
        }

        return $this->product_finder;
    }

    private function allow_request_rate() {
        $ip = isset( $_SERVER['REMOTE_ADDR'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REMOTE_ADDR'] ) ) : 'unknown';
        $key = 'acosmaia_rate_' . md5( $ip );
        $count = (int) get_transient( $key );

        if ( $count >= 20 ) {
            return false;
        }

        set_transient( $key, $count + 1, MINUTE_IN_SECONDS );
        return true;
    }

    private function usage_limit_available() {
        $daily_limit   = (int) get_option( 'acosmaia_daily_limit', 0 );
        $monthly_limit = (int) get_option( 'acosmaia_monthly_limit', 0 );

        $daily_used   = (int) get_option( 'acosmaia_usage_daily_' . current_time( 'Ymd' ), 0 );
        $monthly_used = (int) get_option( 'acosmaia_usage_monthly_' . current_time( 'Ym' ), 0 );

        if ( $daily_limit > 0 && $daily_used >= $daily_limit ) {
            return false;
        }

        if ( $monthly_limit > 0 && $monthly_used >= $monthly_limit ) {
            return false;
        }

        return true;
    }

    private function get_token_finished_message() {
        return 'Token limit finished for now. Please try again later, or ask the site admin to increase chat token limits/API credits.';
    }

    private function is_token_limit_error_message( $error_message ) {
        $text = strtolower( trim( (string) $error_message ) );
        if ( '' === $text ) {
            return false;
        }

        return strpos( $text, 'quota exceeded' ) !== false
            || strpos( $text, 'usage limit reached' ) !== false
            || strpos( $text, 'insufficient credits' ) !== false
            || strpos( $text, 'out of credits' ) !== false
            || strpos( $text, 'token limit' ) !== false
            || strpos( $text, 'billing' ) !== false;
    }

    private function track_usage( array $usage ) {
        $total = isset( $usage['total_tokens'] ) ? (int) $usage['total_tokens'] : 0;
        if ( $total <= 0 ) {
            $prompt_tokens = isset( $usage['prompt_tokens'] ) ? (int) $usage['prompt_tokens'] : 0;
            $completion_tokens = isset( $usage['completion_tokens'] ) ? (int) $usage['completion_tokens'] : 0;
            $total = $prompt_tokens + $completion_tokens;
        }

        if ( $total <= 0 ) {
            return;
        }

        $daily_key   = 'acosmaia_usage_daily_' . current_time( 'Ymd' );
        $monthly_key = 'acosmaia_usage_monthly_' . current_time( 'Ym' );

        update_option( $daily_key, (int) get_option( $daily_key, 0 ) + $total, false );
        update_option( $monthly_key, (int) get_option( $monthly_key, 0 ) + $total, false );
    }

    private function increment_counter( $option_key ) {
        update_option( $option_key, (int) get_option( $option_key, 0 ) + 1, false );
    }

    private function report_error_event( $debug_id, $context, $message ) {
        $payload = [
            'debug_id'  => sanitize_text_field( (string) $debug_id ),
            'context'   => sanitize_key( (string) $context ),
            'message'   => sanitize_text_field( (string) $message ),
            'timestamp' => current_time( 'mysql' ),
        ];

        // Keep the latest error in a short-lived transient for diagnostics without using runtime logs.
        set_transient( 'acosmaia_last_error', $payload, 10 * MINUTE_IN_SECONDS );

        /**
         * Allows custom monitoring integrations to capture chat handler errors.
         *
         * @param array $payload Error payload with debug_id, context, message and timestamp.
         */
        do_action( 'acosmaia_error_event', $payload );
    }

    private function build_system_prompt( array $products, $message ) {
        $store_name  = get_bloginfo( 'name' );
        $assistant   = get_option( 'acosmaia_assistant_name', 'AI Assistant' );
        $knowledge   = get_option( 'acosmaia_knowledge_text', '' );
        $restrict    = get_option( 'acosmaia_restrict_product_only', 'no' ) === 'yes';
        $currency_code = function_exists( 'get_woocommerce_currency' ) ? get_woocommerce_currency() : 'USD';
        $currency_symbol = function_exists( 'get_woocommerce_currency_symbol' ) ? get_woocommerce_currency_symbol() : '$';
        $currency_example = wp_strip_all_tags( wc_price( 1234.56 ) );

        // Compact product context - only essential info
        $product_lines = [];
        foreach ( $products as $product ) {
            if ( ! $product instanceof WC_Product ) {
                continue;
            }

            // Minimal product format to reduce tokens
            $price = $product->get_price();
            $sale_price = $product->get_sale_price();
            $price_text = $sale_price !== ''
                ? wp_strip_all_tags( wc_price( (float) $sale_price ) ) . ' (was ' . wp_strip_all_tags( wc_price( (float) $price ) ) . ')'
                : wp_strip_all_tags( wc_price( (float) $price ) );

            $product_lines[] = sprintf(
                '%s - %s - %s',
                $product->get_name(),
                $price_text,
                $product->is_in_stock() ? 'In stock' : 'Out of stock'
            );
        }

        $product_context = empty( $product_lines ) 
            ? 'No matching products found.' 
            : 'Products: ' . implode( ' | ', array_slice( $product_lines, 0, 3 ) );

        $site_context   = $this->build_site_context();
        $wc_context     = $this->build_woocommerce_context();
        $policy_context = $this->get_policy_context();
        $pages_context  = $this->build_enabled_pages_context();
        $blog_context   = $this->build_blog_page_context( $message );
        $knowledge      = $this->truncate_context( $knowledge, 1800 );

        // Check if enabled pages are available for context
        $has_enabled_pages = strpos( $pages_context, 'No page access enabled' ) === false && strpos( $pages_context, 'No valid enabled pages found' ) === false;

        // Build scope section based on restriction and page availability
        $scope_section = $this->build_scope_section( $restrict, $has_enabled_pages );

        return "You are {$assistant} for {$store_name}. You help customers with shopping questions, product information, store policies, and general inquiries.\n\n" .
            "COMMUNICATION STYLE:\n" .
            "- Be friendly, professional, and concise\n" .
            "- Use clear, simple language\n" .
            "- Ask clarifying questions if the user's request is unclear\n" .
            "- Format responses with line breaks for readability\n" .
            "- Use bullet points for lists when relevant\n\n" .
            "PRODUCT QUESTIONS:\n" .
            "- Use the provided product information below\n" .
            "- If multiple products match, highlight 2-3 best options\n" .
            "- Always include price, availability, and key features\n" .
            "- When product cards are available in the UI, provide a brief summary and let the cards show details\n" .
            "- Never invent products, prices, or specifications\n\n" .
            "SUMMARY REQUESTS:\n" .
            "- When asked to summarize, provide concise key points (3-5 bullet points max)\n" .
            "- Focus on the most important information\n" .
            "- Use clear, easy-to-read formatting\n\n" .
            "PRICING:\n" .
            "- Store currency: {$currency_code} ({$currency_symbol})\n" .
            "- Currency format example: {$currency_example}\n" .
            "- Always quote prices in {$currency_code} unless user asks for conversion\n\n" .
            "ORDER & ACCOUNT QUESTIONS:\n" .
            "- If user mentions orders or account issues, suggest they check My Account or contact support\n" .
            "- Provide links to relevant pages if available\n\n" .
            "POLICY QUESTIONS:\n" .
            "- Answer based on the policies below\n" .
            "- If policy information is not available, direct user to support\n\n" .
            "{$scope_section}\n" .
            "KNOWLEDGE BASE:\n{$knowledge}\n\n" .
            "STORE INFO:\n{$site_context}\n\n" .
            "STORE SETUP:\n{$wc_context}\n\n" .
            "IMPORTANT POLICIES:\n{$policy_context}\n\n" .
            "BLOG & CONTENT:\n{$blog_context}\n\n" .
            "AVAILABLE INFORMATION:\n{$pages_context}\n\n" .
            "AVAILABLE PRODUCTS:\n{$product_context}\n\n" .
            "CRITICAL RULES:\n" .
            "- Never make up or invent products, prices, or features\n" .
            "- If information is not available, say so clearly\n" .
            "- Be helpful within the scope of available information\n" .
            "- Keep responses focused and actionable\n" .
            "- If a question is outside your knowledge, politely explain what information you have access to";
    }

    private function build_scope_section( $restrict, $has_enabled_pages ) {
        if ( $restrict ) {
            return "SCOPE:\n" .
                "- Only answer product and shopping-related questions\n" .
                "- Do not answer general knowledge or off-topic questions\n" .
                "- Focus on helping customers find and learn about products\n" .
                "- Stay on topic and relevant to the store\n";
        }

        if ( $has_enabled_pages ) {
            return "SCOPE:\n" .
                "- Help with shopping, products, and store policies\n" .
                "- Answer questions about the pages and information provided above (these are topics we have content for)\n" .
                "- For general questions not covered by provided pages, you can provide helpful information if relevant to the store\n" .
                "- Stay on topic and helpful to customers\n" .
                "- If a topic is not covered in the provided pages/information, let the user know what you do have access to\n";
        }

        return "SCOPE:\n" .
            "- Help with shopping, products, and store policies\n" .
            "- Answer general customer service questions\n" .
            "- Be helpful and professional in all interactions\n" .
            "- If information is not available, let the user know and suggest contacting support\n";
    }

    private function build_enabled_pages_context() {
        $enabled_pages = get_option( 'acosmaia_enabled_pages', [] );
        if ( ! is_array( $enabled_pages ) || empty( $enabled_pages ) ) {
            return 'No page access enabled.';
        }

        $chunks = [];
        foreach ( array_slice( $enabled_pages, 0, 30 ) as $page_id ) {
            $page_id = absint( $page_id );
            if ( $page_id <= 0 ) {
                continue;
            }

            $page = get_post( $page_id );
            if ( ! $page instanceof WP_Post || 'page' !== $page->post_type || 'publish' !== $page->post_status ) {
                continue;
            }

            $title = sanitize_text_field( get_the_title( $page_id ) );
            $url = esc_url_raw( get_permalink( $page_id ) );
            $content = wp_strip_all_tags( (string) $page->post_content );
            $content = preg_replace( '/\s+/', ' ', trim( $content ) );
            $content = $this->truncate_context( $content, 3000 );

            $chunks[] = "Page: {$title}\nURL: {$url}\nContent: {$content}";
        }

        if ( empty( $chunks ) ) {
            return 'No valid enabled pages found.';
        }

        return $this->truncate_context( implode( "\n\n", $chunks ), 12000 );
    }

    private function build_blog_page_context( $message = '' ) {
        $blog_page_id = (int) get_option( 'page_for_posts', 0 );
        
        if ( $blog_page_id <= 0 ) {
            return 'No blog page configured.';
        }

        $blog_page = get_post( $blog_page_id );
        if ( ! $blog_page instanceof WP_Post || 'page' !== $blog_page->post_type || 'publish' !== $blog_page->post_status ) {
            return 'Blog page exists but is not accessible.';
        }

        $title = sanitize_text_field( get_the_title( $blog_page_id ) );
        $url = esc_url_raw( get_permalink( $blog_page_id ) );
        
        // Get blog page content
        $content = wp_strip_all_tags( (string) $blog_page->post_content );
        $content = preg_replace( '/\s+/', ' ', trim( $content ) );
        $content = $this->truncate_context( $content, 2000 );

        $blog_info = "Blog Page: {$title}\nURL: {$url}";
        if ( ! empty( $content ) ) {
            $blog_info .= "\nContent: {$content}";
        }

        // Check if user is asking about a specific blog post
        if ( ! empty( $message ) && is_string( $message ) && strlen( $message ) > 3 ) {
            $specific_posts = $this->find_blog_posts_matching_query( $message );
            if ( ! empty( $specific_posts ) ) {
                $blog_info .= "\n\nMatching Blog Posts:\n";
                foreach ( $specific_posts as $post ) {
                    if ( ! $post instanceof WP_Post ) {
                        continue;
                    }
                    $post_title = sanitize_text_field( $post->post_title );
                    $post_url = esc_url_raw( get_permalink( $post ) );
                    
                    // Get full post content
                    $post_content = wp_strip_all_tags( $post->post_content );
                    $post_content = preg_replace( '/\s+/', ' ', trim( $post_content ) );
                    $post_content = $this->truncate_context( $post_content, 2000 );
                    
                    $blog_info .= "\nPost: {$post_title}\nURL: {$post_url}\nContent: {$post_content}";
                }
                return $this->truncate_context( $blog_info, 10000 );
            }
        }

        // Get recent posts from blog with full content
        $recent_posts = get_posts( [
            'numberposts' => 10,
            'post_type'   => 'post',
            'post_status' => 'publish',
            'orderby'     => 'date',
            'order'       => 'DESC',
        ] );

        $posts_summary = [];
        if ( ! empty( $recent_posts ) ) {
            foreach ( $recent_posts as $post ) {
                if ( ! $post instanceof WP_Post ) {
                    continue;
                }
                $post_title = sanitize_text_field( $post->post_title );
                $post_url = esc_url_raw( get_permalink( $post ) );
                
                // Get post excerpt or content
                $post_content = '';
                if ( ! empty( $post->post_excerpt ) ) {
                    $post_content = wp_strip_all_tags( $post->post_excerpt );
                } else {
                    $post_content = wp_strip_all_tags( $post->post_content );
                }
                
                // Clean up whitespace
                $post_content = preg_replace( '/\s+/', ' ', trim( $post_content ) );
                $post_content = $this->truncate_context( $post_content, 800 );
                
                $posts_summary[] = "Post: {$post_title}\nURL: {$post_url}\nContent: {$post_content}";
            }
        }

        if ( ! empty( $posts_summary ) ) {
            $blog_info .= "\n\nRecent Posts:\n" . implode( "\n\n", $posts_summary );
        }

        return $this->truncate_context( $blog_info, 8000 );
    }

    private function find_blog_posts_matching_query( $message ) {
        if ( ! is_string( $message ) || strlen( trim( $message ) ) < 3 ) {
            return [];
        }

        // Search for posts matching keywords from the message
        $search_terms = $this->extract_search_keywords( strtolower( $message ) );
        if ( empty( $search_terms ) ) {
            return [];
        }

        // Try to find exact title matches first
        $posts = get_posts( [
            'numberposts' => 5,
            'post_type'   => 'post',
            'post_status' => 'publish',
            's'           => $search_terms,
            'orderby'     => 'relevance',
        ] );

        // Filter to only include posts that have a reasonable match
        $matched = [];
        if ( ! empty( $posts ) ) {
            $query_lower = strtolower( $message );
            foreach ( $posts as $post ) {
                if ( ! $post instanceof WP_Post ) {
                    continue;
                }
                $post_title_lower = strtolower( $post->post_title );
                $post_content_lower = strtolower( wp_strip_all_tags( $post->post_content ) );
                
                // Check if post title or content contains significant portion of the query
                $title_match = 0;
                $terms = explode( ' ', $search_terms );
                foreach ( $terms as $term ) {
                    if ( ! empty( $term ) && strlen( $term ) > 2 ) {
                        if ( strpos( $post_title_lower, $term ) !== false ) {
                            $title_match += 2;
                        } elseif ( strpos( $post_content_lower, $term ) !== false ) {
                            $title_match += 1;
                        }
                    }
                }
                
                if ( $title_match > 0 ) {
                    $matched[] = $post;
                }
            }
        }

        return $matched;
    }


    private function build_site_context() {
        $cache_key = 'acosmaia_site_context_v2';
        $cached    = get_transient( $cache_key );

        if ( is_string( $cached ) && $cached !== '' ) {
            return $cached;
        }

        $lines = [];
        $lines[] = 'Site name: ' . sanitize_text_field( get_bloginfo( 'name' ) );
        $lines[] = 'Tagline: ' . sanitize_text_field( get_bloginfo( 'description' ) );
        $lines[] = 'Site URL: ' . esc_url_raw( home_url( '/' ) );
        $lines[] = 'Language: ' . sanitize_text_field( get_bloginfo( 'language' ) );
        $lines[] = 'Timezone: ' . sanitize_text_field( (string) wp_timezone_string() );
        $lines[] = 'Date format: ' . sanitize_text_field( (string) get_option( 'date_format', 'F j, Y' ) );
        $lines[] = 'Time format: ' . sanitize_text_field( (string) get_option( 'time_format', 'g:i a' ) );

        $admin_email = get_option( 'admin_email', '' );
        if ( is_email( $admin_email ) ) {
            $lines[] = 'Admin email: ' . sanitize_email( $admin_email );
        }

        if ( function_exists( 'wp_get_theme' ) ) {
            $theme = wp_get_theme();
            if ( $theme ) {
                $lines[] = 'Theme: ' . sanitize_text_field( (string) $theme->get( 'Name' ) );
            }
        }

        $important_pages = [];
        if ( (int) get_option( 'page_on_front', 0 ) > 0 ) {
            $important_pages[] = [
                'label' => 'Front page',
                'id'    => (int) get_option( 'page_on_front', 0 ),
            ];
        }
        if ( (int) get_option( 'page_for_posts', 0 ) > 0 ) {
            $important_pages[] = [
                'label' => 'Blog page',
                'id'    => (int) get_option( 'page_for_posts', 0 ),
            ];
        }
        if ( (int) get_option( 'wp_page_for_privacy_policy', 0 ) > 0 ) {
            $important_pages[] = [
                'label' => 'Privacy policy',
                'id'    => (int) get_option( 'wp_page_for_privacy_policy', 0 ),
            ];
        }

        foreach ( $important_pages as $page_ref ) {
            $page_id = isset( $page_ref['id'] ) ? (int) $page_ref['id'] : 0;
            if ( $page_id <= 0 ) {
                continue;
            }

            $title = get_the_title( $page_id );
            $url   = get_permalink( $page_id );
            if ( ! $title || ! $url ) {
                continue;
            }

            $lines[] = sanitize_text_field( (string) $page_ref['label'] ) . ': ' . sanitize_text_field( $title ) . ' (' . esc_url_raw( $url ) . ')';
        }

        $context = $this->truncate_context( implode( "\n", array_filter( $lines ) ), 2400 );
        set_transient( $cache_key, $context, 10 * MINUTE_IN_SECONDS );

        return $context;
    }

    private function build_woocommerce_context() {
        if ( ! class_exists( 'WooCommerce' ) ) {
            return 'WooCommerce not installed.';
        }

        $cache_key = 'acosmaia_wc_context_v3';
        $cached    = get_transient( $cache_key );

        if ( is_string( $cached ) && $cached !== '' ) {
            return $cached;
        }

        $lines = [];
        $currency_code   = function_exists( 'get_woocommerce_currency' ) ? get_woocommerce_currency() : 'USD';
        $currency_symbol = function_exists( 'get_woocommerce_currency_symbol' ) ? get_woocommerce_currency_symbol() : '$';
        $currency_pos    = (string) get_option( 'woocommerce_currency_pos', 'left' );

        $lines[] = 'Currency: ' . sanitize_text_field( $currency_code ) . ' (' . sanitize_text_field( $currency_symbol ) . ')';
        $lines[] = 'Currency position: ' . sanitize_text_field( $currency_pos );
        $lines[] = 'Weight unit: ' . sanitize_text_field( (string) get_option( 'woocommerce_weight_unit', 'kg' ) );
        $lines[] = 'Dimension unit: ' . sanitize_text_field( (string) get_option( 'woocommerce_dimension_unit', 'cm' ) );
        $lines[] = 'Prices include tax: ' . ( get_option( 'woocommerce_prices_include_tax', 'no' ) === 'yes' ? 'yes' : 'no' );
        $lines[] = 'Tax enabled: ' . ( get_option( 'woocommerce_calc_taxes', 'no' ) === 'yes' ? 'yes' : 'no' );
        $lines[] = 'Coupons enabled: ' . ( get_option( 'woocommerce_enable_coupons', 'yes' ) === 'yes' ? 'yes' : 'no' );
        $lines[] = 'Manage stock: ' . ( get_option( 'woocommerce_manage_stock', 'yes' ) === 'yes' ? 'yes' : 'no' );

        $shop_page_url = function_exists( 'wc_get_page_permalink' ) ? wc_get_page_permalink( 'shop' ) : '';
        $cart_url = function_exists( 'wc_get_cart_url' ) ? wc_get_cart_url() : '';
        $checkout_url = function_exists( 'wc_get_checkout_url' ) ? wc_get_checkout_url() : '';
        $myaccount_url = function_exists( 'wc_get_page_permalink' ) ? wc_get_page_permalink( 'myaccount' ) : '';
        if ( $shop_page_url ) {
            $lines[] = 'Shop URL: ' . esc_url_raw( $shop_page_url );
        }
        if ( $cart_url ) {
            $lines[] = 'Cart URL: ' . esc_url_raw( $cart_url );
        }
        if ( $checkout_url ) {
            $lines[] = 'Checkout URL: ' . esc_url_raw( $checkout_url );
        }
        if ( $myaccount_url ) {
            $lines[] = 'My account URL: ' . esc_url_raw( $myaccount_url );
        }

        $product_counts = wp_count_posts( 'product' );
        if ( $product_counts ) {
            $lines[] = sprintf(
                'Product counts: publish=%d draft=%d pending=%d private=%d',
                isset( $product_counts->publish ) ? (int) $product_counts->publish : 0,
                isset( $product_counts->draft ) ? (int) $product_counts->draft : 0,
                isset( $product_counts->pending ) ? (int) $product_counts->pending : 0,
                isset( $product_counts->private ) ? (int) $product_counts->private : 0
            );
        }

        $sale_ids = function_exists( 'wc_get_product_ids_on_sale' ) ? wc_get_product_ids_on_sale() : [];
        $featured_ids = function_exists( 'wc_get_featured_product_ids' ) ? wc_get_featured_product_ids() : [];
        $lines[] = 'On-sale products: ' . count( (array) $sale_ids );
        $lines[] = 'Featured products: ' . count( (array) $featured_ids );

        $recent_products = wc_get_products( [
            'limit'  => 20,
            'status' => 'publish',
            'return' => 'objects',
            'orderby' => 'date',
            'order' => 'DESC',
        ] );

        $price_values = [];
        $recent_lines = [];
        foreach ( $recent_products as $product ) {
            if ( ! $product instanceof WC_Product ) {
                continue;
            }

            $price = (float) $product->get_price();
            if ( $price > 0 ) {
                $price_values[] = $price;
            }

            $recent_lines[] = sprintf(
                '#%d %s | SKU: %s | Price: %s | Stock: %s | Categories: %s',
                (int) $product->get_id(),
                sanitize_text_field( $product->get_name() ),
                sanitize_text_field( (string) $product->get_sku() ),
                wp_strip_all_tags( wc_price( $price ) ),
                $product->is_in_stock() ? 'instock' : 'outofstock',
                wp_strip_all_tags( wc_get_product_category_list( $product->get_id(), ', ', '', '' ) )
            );
        }

        if ( ! empty( $price_values ) ) {
            $lines[] = 'Recent product price range: min=' . wp_strip_all_tags( wc_price( min( $price_values ) ) ) . ' max=' . wp_strip_all_tags( wc_price( max( $price_values ) ) );
            $lines[] = 'Recent product avg price: ' . wp_strip_all_tags( wc_price( array_sum( $price_values ) / max( 1, count( $price_values ) ) ) );
        }

        $categories = get_terms( [
            'taxonomy'   => 'product_cat',
            'hide_empty' => false,
            'number'     => 40,
            'orderby'    => 'count',
            'order'      => 'DESC',
        ] );
        if ( is_array( $categories ) && ! is_wp_error( $categories ) ) {
            $cat_lines = [];
            foreach ( $categories as $cat ) {
                if ( ! $cat instanceof WP_Term ) {
                    continue;
                }

                $cat_lines[] = sanitize_text_field( $cat->name ) . ' (' . (int) $cat->count . ')';
            }

            if ( ! empty( $cat_lines ) ) {
                $lines[] = 'Product categories: ' . implode( ', ', $cat_lines );
            }
        }

        $tags = get_terms( [
            'taxonomy'   => 'product_tag',
            'hide_empty' => false,
            'number'     => 40,
            'orderby'    => 'count',
            'order'      => 'DESC',
        ] );
        if ( is_array( $tags ) && ! is_wp_error( $tags ) ) {
            $tag_lines = [];
            foreach ( $tags as $tag ) {
                if ( ! $tag instanceof WP_Term ) {
                    continue;
                }

                $tag_lines[] = sanitize_text_field( $tag->name ) . ' (' . (int) $tag->count . ')';
            }

            if ( ! empty( $tag_lines ) ) {
                $lines[] = 'Product tags: ' . implode( ', ', $tag_lines );
            }
        }

        if ( function_exists( 'wc_get_attribute_taxonomies' ) ) {
            $attribute_taxonomies = wc_get_attribute_taxonomies();
            if ( is_array( $attribute_taxonomies ) ) {
                $attr_lines = [];
                foreach ( $attribute_taxonomies as $attribute_taxonomy ) {
                    if ( ! isset( $attribute_taxonomy->attribute_name ) ) {
                        continue;
                    }

                    $attr_lines[] = sanitize_text_field( (string) $attribute_taxonomy->attribute_label ) . ' (' . sanitize_text_field( (string) $attribute_taxonomy->attribute_name ) . ')';
                }

                if ( ! empty( $attr_lines ) ) {
                    $lines[] = 'Global attributes: ' . implode( ', ', $attr_lines );
                }
            }
        }

        if ( function_exists( 'WC' ) && WC()->payment_gateways() ) {
            $gateway_lines = [];
            $available_gateways = WC()->payment_gateways()->payment_gateways();
            foreach ( $available_gateways as $gateway ) {
                if ( ! isset( $gateway->id ) ) {
                    continue;
                }

                $gateway_lines[] = sanitize_text_field( (string) $gateway->id ) . ':' . ( ! empty( $gateway->enabled ) && $gateway->enabled === 'yes' ? 'enabled' : 'disabled' );
            }

            if ( ! empty( $gateway_lines ) ) {
                $lines[] = 'Payment gateways: ' . implode( ', ', $gateway_lines );
            }
        }

        if ( class_exists( 'WC_Shipping_Zones' ) ) {
            $shipping_zone_lines = [];
            $zones = WC_Shipping_Zones::get_zones();
            foreach ( $zones as $zone ) {
                if ( empty( $zone['zone_name'] ) || empty( $zone['shipping_methods'] ) ) {
                    continue;
                }

                $method_lines = [];
                foreach ( $zone['shipping_methods'] as $method ) {
                    if ( ! isset( $method->id ) ) {
                        continue;
                    }

                    $method_lines[] = sanitize_text_field( (string) $method->id ) . ':' . ( ! empty( $method->enabled ) && $method->enabled === 'yes' ? 'enabled' : 'disabled' );
                }

                if ( ! empty( $method_lines ) ) {
                    $shipping_zone_lines[] = sanitize_text_field( (string) $zone['zone_name'] ) . ' [' . implode( ', ', $method_lines ) . ']';
                }
            }

            if ( ! empty( $shipping_zone_lines ) ) {
                $lines[] = 'Shipping zones: ' . implode( ' | ', $shipping_zone_lines );
            }
        }

        if ( ! empty( $recent_lines ) ) {
            $lines[] = 'Recent products: ' . implode( ' || ', array_slice( $recent_lines, 0, 20 ) );
        }

        $context = $this->truncate_context( implode( "\n", array_filter( $lines ) ), 12000 );
        set_transient( $cache_key, $context, 10 * MINUTE_IN_SECONDS );

        return $context;
    }

    private function truncate_context( $text, $max_chars ) {
        $text = trim( (string) $text );
        $max  = max( 200, (int) $max_chars );

        if ( strlen( $text ) <= $max ) {
            return $text;
        }

        return substr( $text, 0, $max ) . '...';
    }

    private function get_policy_context() {
        $pages = [
            'shipping' => wc_get_page_permalink( 'shop' ),
            'refund'   => function_exists( 'wc_get_account_endpoint_url' ) ? wc_get_account_endpoint_url( 'orders' ) : '',
        ];

        $policy_snippets = [];
        foreach ( $pages as $label => $url ) {
            if ( ! $url ) {
                continue;
            }

            $policy_snippets[] = ucfirst( $label ) . ' URL: ' . esc_url_raw( $url );
        }

        $manual = get_option( 'acosmaia_knowledge_text', '' );
        if ( $manual !== '' ) {
            $policy_snippets[] = 'Manual policy note: ' . sanitize_textarea_field( $manual );
        }

        return $this->truncate_context( implode( "\n", $policy_snippets ), 1800 );
    }

    private function should_plan_product_query( $message_lower ) {
        if ( ! is_string( $message_lower ) || '' === $message_lower ) {
            return false;
        }

        return (bool) preg_match(
            '/(product|products|price|pricing|cost|budget|under|below|in stock|stock|available|compare|similar|recommend|suggest|buy|purchase|shipping|delivery|refund|return|category|brand|color|size|sale|discount|offer)/i',
            $message_lower
        );
    }

    private function get_blocking_access_warning( $message_lower ) {
        $page_warning = $this->get_page_access_warning( $message_lower );
        if ( '' !== $page_warning ) {
            return $page_warning;
        }

        $shop_warning = $this->get_shop_access_warning( $message_lower );
        if ( '' !== $shop_warning ) {
            return $shop_warning;
        }

        return '';
    }

    private function get_page_access_warning( $message_lower ) {
        if ( ! $this->looks_like_page_access_request( $message_lower ) ) {
            return '';
        }

        $enabled_pages = $this->get_enabled_page_ids();
        if ( empty( $enabled_pages ) ) {
            return 'Warning: Page access is not enabled. Enable pages in admin to allow AI to use page content.';
        }

        $requested_pages = $this->get_requested_page_ids( $message_lower );
        if ( empty( $requested_pages ) ) {
            return '';
        }

        foreach ( $requested_pages as $requested_page_id ) {
            if ( in_array( $requested_page_id, $enabled_pages, true ) ) {
                return '';
            }
        }

        return 'Warning: This page is not enabled for AI access. Enable it in admin to allow page content responses.';
    }

    private function get_shop_access_warning( $message_lower ) {
        if ( ! $this->looks_like_product_request( $message_lower ) ) {
            return '';
        }

        if ( ! function_exists( 'wc_get_page_id' ) ) {
            return '';
        }

        $shop_page_id = (int) wc_get_page_id( 'shop' );
        if ( $shop_page_id <= 0 ) {
            return '';
        }

        $enabled_pages = $this->get_enabled_page_ids();
        if ( in_array( $shop_page_id, $enabled_pages, true ) ) {
            return '';
        }

        return 'Warning: Shop page access is disabled. Enable the Shop page in admin to allow product responses.';
    }

    private function looks_like_product_request( $message_lower ) {
        if ( ! is_string( $message_lower ) || '' === $message_lower ) {
            return false;
        }

        return (bool) preg_match(
            '/\b(product|products|shop|catalog|catalogue|price|pricing|stock|available|compare|recommend|suggest|buy|purchase|cart|sku)\b/i',
            $message_lower
        );
    }

    private function get_enabled_page_ids() {
        $enabled_pages = get_option( 'acosmaia_enabled_pages', [] );
        if ( ! is_array( $enabled_pages ) ) {
            return [];
        }

        $ids = [];
        foreach ( $enabled_pages as $item ) {
            $id = absint( $item );
            if ( $id > 0 ) {
                $ids[] = $id;
            }
        }

        return array_values( array_unique( $ids ) );
    }

    private function get_requested_page_ids( $message_lower ) {
        if ( ! is_string( $message_lower ) || '' === $message_lower ) {
            return [];
        }

        $pages = get_pages( [
            'sort_column' => 'menu_order,post_title',
            'post_status' => 'publish',
            'number'      => 150,
        ] );

        if ( ! is_array( $pages ) || empty( $pages ) ) {
            return [];
        }

        $requested = [];
        foreach ( $pages as $page ) {
            if ( ! $page instanceof WP_Post ) {
                continue;
            }

            $title = strtolower( trim( (string) $page->post_title ) );
            $slug  = strtolower( trim( (string) $page->post_name ) );

            if ( ( '' !== $title && strpos( $message_lower, $title ) !== false ) || ( '' !== $slug && strpos( $message_lower, $slug ) !== false ) ) {
                $requested[] = (int) $page->ID;
            }
        }

        return array_values( array_unique( $requested ) );
    }

    private function looks_like_page_access_request( $message_lower ) {
        if ( ! is_string( $message_lower ) || '' === $message_lower ) {
            return false;
        }

        return (bool) preg_match(
            '/\b(page|pages|about|contact|policy|terms|privacy|shipping|refund|return|faq|support|company|who\s+are\s+you|about\s+us|contact\s+us)\b/i',
            $message_lower
        );
    }

    private function should_lookup_products( $message_lower, array $query_plan ) {
        if ( isset( $query_plan['intent'] ) && is_string( $query_plan['intent'] ) && $query_plan['intent'] !== 'none' ) {
            return true;
        }

        if ( ! empty( $query_plan['search'] ) || ! empty( $query_plan['max_price'] ) || ! empty( $query_plan['in_stock_only'] ) || ! empty( $query_plan['compare_items'] ) ) {
            return true;
        }

        // If message still has meaningful search terms (for example, "show sunglass"),
        // do product lookup even when planner is skipped.
        if ( $this->extract_search_keywords( $message_lower ) !== '' ) {
            return true;
        }

        return $this->should_plan_product_query( $message_lower );
    }

    private function generate_product_query_plan( $api_key, $message ) {
        $planner_prompt = "You convert a customer chat request into WooCommerce product query JSON.\n" .
            "Return JSON only with these keys: intent, search, max_price, in_stock_only, compare_items, sort_by.\n" .
            "intent values: search | compare | lowest_price | most_expensive | most_reviewed | none\n" .
            "sort_by values: none | price_asc | price_desc | rating_desc\n" .
            "compare_items must be an array of up to 2 product phrases when intent=compare.\n" .
            "If no price found, use null for max_price.\n" .
            "No markdown and no explanation, only JSON object.";

        $ai_client = ACOSMAIA_AI_API_Client::from_settings();
        if ( ! $ai_client->is_configured() ) {
            return [];
        }

        $planner_response = $ai_client->request( $planner_prompt, (string) $message );
        if ( is_wp_error( $planner_response ) ) {
            return [];
        }

        $parsed = $ai_client->parse_response( $planner_response );
        if ( isset( $parsed['error'] ) ) {
            return [];
        }

        $response_content = isset( $parsed['content'] ) ? $parsed['content'] : '';
        $response_usage = isset( $parsed['usage'] ) ? $parsed['usage'] : [];

        if ( empty( $response_content ) ) {
            return [];
        }

        $this->track_usage( $response_usage );

        $raw_plan = $this->decode_json_from_text( $response_content );
        if ( ! is_array( $raw_plan ) ) {
            return [];
        }

        $allowed_intents = [ 'search', 'compare', 'lowest_price', 'most_expensive', 'most_reviewed', 'none' ];
        $allowed_sorts   = [ 'none', 'price_asc', 'price_desc', 'rating_desc' ];

        $intent = isset( $raw_plan['intent'] ) ? sanitize_text_field( strtolower( (string) $raw_plan['intent'] ) ) : 'none';
        $sort_by = isset( $raw_plan['sort_by'] ) ? sanitize_text_field( strtolower( (string) $raw_plan['sort_by'] ) ) : 'none';

        $compare_items = [];
        if ( isset( $raw_plan['compare_items'] ) && is_array( $raw_plan['compare_items'] ) ) {
            foreach ( array_slice( $raw_plan['compare_items'], 0, 2 ) as $item ) {
                $clean = sanitize_text_field( (string) $item );
                if ( strlen( $clean ) >= 2 ) {
                    $compare_items[] = $clean;
                }
            }
        }

        return [
            'intent'        => in_array( $intent, $allowed_intents, true ) ? $intent : 'none',
            'search'        => isset( $raw_plan['search'] ) ? sanitize_text_field( (string) $raw_plan['search'] ) : '',
            'max_price'     => isset( $raw_plan['max_price'] ) && is_numeric( $raw_plan['max_price'] ) ? (float) $raw_plan['max_price'] : null,
            'in_stock_only' => ! empty( $raw_plan['in_stock_only'] ),
            'compare_items' => $compare_items,
            'sort_by'       => in_array( $sort_by, $allowed_sorts, true ) ? $sort_by : 'none',
        ];
    }

    private function decode_json_from_text( $text ) {
        $trimmed = trim( (string) $text );
        if ( '' === $trimmed ) {
            return null;
        }

        if ( preg_match( '/```(?:json)?\s*(\{[\s\S]*\})\s*```/i', $trimmed, $matches ) ) {
            $trimmed = trim( $matches[1] );
        }

        $decoded = json_decode( $trimmed, true );
        return is_array( $decoded ) ? $decoded : null;
    }

    private function get_fallback_models( $preferred_model, $api_key = '' ) {
        $dynamic_free_models = $this->get_openrouter_free_models( $api_key );
        $candidates = array_merge(
            [ $preferred_model ],
            $dynamic_free_models,
            [
                'mistralai/mistral-7b-instruct:free',
                'google/gemma-2-9b-it:free',
                'meta-llama/llama-3.1-8b-instruct:free',
            ]
        );

        $models = [];
        foreach ( $candidates as $candidate ) {
            $candidate = trim( (string) $candidate );
            if ( '' === $candidate || in_array( $candidate, $models, true ) ) {
                continue;
            }
            $models[] = $candidate;
        }

        return $models;
    }

    private function get_openrouter_free_models( $api_key ) {
        $cache_key = 'acosmaia_openrouter_free_models';
        $cached    = get_transient( $cache_key );
        if ( is_array( $cached ) && ! empty( $cached ) ) {
            return $cached;
        }

        $headers = [
            'Content-Type' => 'application/json',
            'HTTP-Referer' => home_url( '/' ),
            'X-Title'      => get_bloginfo( 'name' ),
        ];

        if ( $api_key ) {
            $headers['Authorization'] = 'Bearer ' . $api_key;
        }

        $response = wp_remote_get( 'https://openrouter.ai/api/v1/models', [
            'headers' => $headers,
            'timeout' => 15,
        ] );

        if ( is_wp_error( $response ) ) {
            return [];
        }

        $status_code = (int) wp_remote_retrieve_response_code( $response );
        if ( $status_code < 200 || $status_code > 299 ) {
            return [];
        }

        $body = json_decode( (string) wp_remote_retrieve_body( $response ), true );
        if ( empty( $body['data'] ) || ! is_array( $body['data'] ) ) {
            return [];
        }

        $models = [];
        foreach ( $body['data'] as $item ) {
            if ( empty( $item['id'] ) || ! is_string( $item['id'] ) ) {
                continue;
            }

            $id = trim( $item['id'] );
            if ( '' === $id || strpos( $id, ':free' ) === false ) {
                continue;
            }

            $models[] = $id;
        }

        if ( ! empty( $models ) ) {
            set_transient( $cache_key, $models, 6 * HOUR_IN_SECONDS );
        }

        return $models;
    }

    private function find_relevant_products( $message, array $query_plan = [] ) {
        $message_lower = strtolower( $message );
        $intent = isset( $query_plan['intent'] ) && is_string( $query_plan['intent'] ) && $query_plan['intent'] !== ''
            ? $query_plan['intent']
            : $this->detect_product_query_intent( $message_lower );
        $browse_request = $this->looks_like_browse_products_request( $message_lower );
        
        // Extract meaningful keywords (remove stop words)
        $search_term = '';
        if ( isset( $query_plan['search'] ) && is_string( $query_plan['search'] ) ) {
            $search_term = sanitize_text_field( $query_plan['search'] );
        }

        if ( '' === $search_term ) {
            $search_term = $this->extract_search_keywords( $message_lower );
        }

        // Generic browse/list requests should show product cards without forcing a text search.
        if ( $browse_request && in_array( $search_term, [ 'shop', 'catalog', 'catalogue', 'products', 'product' ], true ) ) {
            $search_term = '';
        }

        $max_price = isset( $query_plan['max_price'] ) && is_numeric( $query_plan['max_price'] )
            ? (float) $query_plan['max_price']
            : $this->extract_max_price( $message );

        $min_price = $this->extract_min_price( $message );

        $in_stock_only = ! empty( $query_plan['in_stock_only'] )
            || strpos( $message_lower, 'in stock' ) !== false
            || strpos( $message_lower, 'available' ) !== false;

        $compare_items = [];
        if ( isset( $query_plan['compare_items'] ) && is_array( $query_plan['compare_items'] ) ) {
            $compare_items = array_slice( $query_plan['compare_items'], 0, 2 );
        }

        if ( empty( $compare_items ) && 'compare' === $intent ) {
            $compare_items = $this->extract_compare_items( $message );
        }

        if ( 'compare' === $intent && count( $compare_items ) >= 2 ) {
            $compared_products = $this->find_products_for_comparison( $compare_items, $max_price, $in_stock_only );
            if ( ! empty( $compared_products ) ) {
                return $compared_products;
            }
        }
        
        // Don't search if no meaningful keywords extracted and no product-specific intent detected.
        if ( empty( $search_term ) && null === $max_price && null === $min_price && 'none' === $intent && ! $browse_request ) {
            return [];
        }
        
        $args = [
            'limit'  => 4, // Fetch one extra item to detect whether "show more" should be displayed.
            'status' => 'publish',
            'return' => 'objects',
        ];

        if ( ! empty( $search_term ) ) {
            $args['s'] = $search_term;
        }

        if ( null !== $max_price ) {
            $args['max_price'] = (string) $max_price;
        }

        if ( null !== $min_price ) {
            $args['min_price'] = (string) $min_price;
        }

        $sort_by = isset( $query_plan['sort_by'] ) && is_string( $query_plan['sort_by'] ) ? $query_plan['sort_by'] : 'none';
        if ( 'price_asc' === $sort_by || 'lowest_price' === $intent || ( null !== $max_price && empty( $search_term ) ) ) {
            $args['orderby'] = 'price';
            $args['order']   = 'ASC';
        } elseif ( 'price_desc' === $sort_by ) {
            $args['orderby'] = 'price';
            $args['order']   = 'DESC';
        } elseif ( 'rating_desc' === $sort_by || 'most_reviewed' === $intent ) {
            // WooCommerce supports rating sort; this is the closest built-in approximation.
            $args['orderby'] = 'rating';
            $args['order']   = 'DESC';
        }

        if ( $in_stock_only ) {
            $args['stock_status'] = 'instock';
        }

        $products = wc_get_products( $args );

        $products = $this->apply_price_and_stock_filters( $products, $min_price, $max_price, $in_stock_only );

        if ( empty( $products ) && ! empty( $search_term ) ) {
            $products = $this->fallback_products_by_partial_name( $search_term, $max_price, $in_stock_only );
            $products = $this->apply_price_and_stock_filters( $products, $min_price, $max_price, $in_stock_only );
        }

        if ( empty( $products ) && ( null !== $min_price || null !== $max_price ) ) {
            $products = $this->fallback_products_by_price_range( $search_term, $min_price, $max_price, $in_stock_only );
        }

        $has_more = count( $products ) > 3;
        $this->last_product_meta = [
            'has_more'      => $has_more,
            'show_more_url' => $has_more ? $this->resolve_show_more_url( $message_lower, $search_term ) : '',
        ];

        if ( $has_more ) {
            $products = array_slice( $products, 0, 3 );
        }

        return $products;
    }

    private function apply_price_and_stock_filters( array $products, $min_price = null, $max_price = null, $in_stock_only = false ) {
        $filtered = [];

        foreach ( $products as $product ) {
            if ( ! $product instanceof WC_Product ) {
                continue;
            }

            if ( $in_stock_only && ! $product->is_in_stock() ) {
                continue;
            }

            $price = (float) $product->get_price();
            if ( null !== $min_price && $price < (float) $min_price ) {
                continue;
            }

            if ( null !== $max_price && $price > (float) $max_price ) {
                continue;
            }

            $filtered[] = $product;
        }

        return $filtered;
    }

    private function fallback_products_by_price_range( $search_term = '', $min_price = null, $max_price = null, $in_stock_only = false ) {
        $candidates = wc_get_products( [
            'limit'   => 60,
            'status'  => 'publish',
            'return'  => 'objects',
            'orderby' => 'date',
            'order'   => 'DESC',
        ] );

        $filtered = $this->apply_price_and_stock_filters( $candidates, $min_price, $max_price, $in_stock_only );

        $term = strtolower( trim( (string) $search_term ) );
        if ( $term === '' ) {
            return array_slice( $filtered, 0, 4 );
        }

        $matched = [];
        foreach ( $filtered as $product ) {
            if ( ! $product instanceof WC_Product ) {
                continue;
            }

            $haystack = strtolower( $product->get_name() . ' ' . $product->get_slug() );
            if ( strpos( $haystack, $term ) === false ) {
                continue;
            }

            $matched[] = $product;
            if ( count( $matched ) >= 4 ) {
                break;
            }
        }

        return $matched;
    }

    private function get_show_more_url_for_products() {
        return isset( $this->last_product_meta['show_more_url'] )
            ? esc_url_raw( (string) $this->last_product_meta['show_more_url'] )
            : '';
    }

    private function resolve_show_more_url( $message_lower, $search_term = '' ) {
        $matched_term_url = $this->find_matching_term_url( 'product_cat', $message_lower, $search_term );
        if ( $matched_term_url !== '' ) {
            return $matched_term_url;
        }

        $matched_tag_url = $this->find_matching_term_url( 'product_tag', $message_lower, $search_term );
        if ( $matched_tag_url !== '' ) {
            return $matched_tag_url;
        }

        $shop_url = function_exists( 'wc_get_page_permalink' ) ? wc_get_page_permalink( 'shop' ) : '';
        return $shop_url ? esc_url_raw( $shop_url ) : esc_url_raw( home_url( '/' ) );
    }

    private function find_matching_term_url( $taxonomy, $message_lower, $search_term = '' ) {
        $terms = get_terms( [
            'taxonomy'   => $taxonomy,
            'hide_empty' => true,
            'number'     => 80,
        ] );

        if ( is_wp_error( $terms ) || ! is_array( $terms ) ) {
            return '';
        }

        $haystack = strtolower( trim( $message_lower . ' ' . $search_term ) );
        if ( $haystack === '' ) {
            return '';
        }

        foreach ( $terms as $term ) {
            if ( ! $term instanceof WP_Term ) {
                continue;
            }

            $name = strtolower( trim( (string) $term->name ) );
            $slug = strtolower( trim( (string) $term->slug ) );
            if ( ( $name !== '' && strpos( $haystack, $name ) !== false ) || ( $slug !== '' && strpos( $haystack, $slug ) !== false ) ) {
                $url = get_term_link( $term );
                return is_wp_error( $url ) ? '' : esc_url_raw( $url );
            }
        }

        return '';
    }

    private function extract_compare_items( $message ) {
        if ( preg_match( '/compare\s+(.+?)\s+(?:and|vs|versus)\s+(.+)/i', $message, $matches ) ) {
            $left  = sanitize_text_field( trim( $matches[1], " \t\n\r\0\x0B\"'" ) );
            $right = sanitize_text_field( trim( $matches[2], " \t\n\r\0\x0B\"'" ) );

            $items = [];
            if ( strlen( $left ) >= 2 ) {
                $items[] = $left;
            }
            if ( strlen( $right ) >= 2 ) {
                $items[] = $right;
            }

            return $items;
        }

        return [];
    }

    private function find_products_for_comparison( array $compare_items, $max_price = null, $in_stock_only = false ) {
        $products = [];

        foreach ( array_slice( $compare_items, 0, 2 ) as $item ) {
            $term = sanitize_text_field( (string) $item );
            if ( '' === $term ) {
                continue;
            }

            $args = [
                'limit'  => 1,
                'status' => 'publish',
                'return' => 'objects',
                's'      => $term,
            ];

            if ( null !== $max_price ) {
                $args['max_price'] = (string) $max_price;
            }

            if ( $in_stock_only ) {
                $args['stock_status'] = 'instock';
            }

            $matches = wc_get_products( $args );
            if ( empty( $matches ) || ! $matches[0] instanceof WC_Product ) {
                continue;
            }

            $product = $matches[0];
            $product_id = $product->get_id();
            if ( isset( $products[ $product_id ] ) ) {
                continue;
            }

            $products[ $product_id ] = $product;
        }

        return array_values( $products );
    }

    private function detect_product_query_intent( $message_lower ) {
        if ( preg_match( '/(compare|\svs\s|versus)/i', $message_lower ) ) {
            return 'compare';
        }

        if ( preg_match( '/(most\s+reviewed|top\s+reviewed|highest\s+rated|best\s+rated)/i', $message_lower ) ) {
            return 'most_reviewed';
        }

        if ( preg_match( '/(lowest|cheapest|least\s+expensive|minimum).*(price|pricing|cost)|lowest\s+pricing/i', $message_lower ) ) {
            return 'lowest_price';
        }

        return 'none';
    }

    private function fallback_products_by_partial_name( $search_term, $max_price = null, $in_stock_only = false ) {
        $term = strtolower( sanitize_text_field( (string) $search_term ) );
        if ( '' === $term ) {
            return [];
        }

        $needles = [ $term ];
        if ( substr( $term, -2 ) === 'es' && strlen( $term ) > 4 ) {
            $needles[] = substr( $term, 0, -2 );
        }
        if ( substr( $term, -1 ) === 's' && strlen( $term ) > 3 ) {
            $needles[] = substr( $term, 0, -1 );
        }

        $candidates = wc_get_products( [
            'limit'  => 40,
            'status' => 'publish',
            'return' => 'objects',
            'orderby' => 'date',
            'order' => 'DESC',
        ] );

        $matched = [];
        foreach ( $candidates as $product ) {
            if ( ! $product instanceof WC_Product ) {
                continue;
            }

            $price = (float) $product->get_price();
            if ( null !== $max_price && $price > (float) $max_price ) {
                continue;
            }

            if ( $in_stock_only && ! $product->is_in_stock() ) {
                continue;
            }

            $haystack = strtolower( $product->get_name() . ' ' . $product->get_slug() );
            $is_match = false;
            foreach ( $needles as $needle ) {
                if ( $needle !== '' && strpos( $haystack, $needle ) !== false ) {
                    $is_match = true;
                    break;
                }
            }

            if ( ! $is_match ) {
                continue;
            }

            $matched[] = $product;
            if ( count( $matched ) >= 3 ) {
                break;
            }
        }

        return $matched;
    }

    private function extract_search_keywords( $message_lower ) {
        // Common stop words to remove
        $stop_words = [
            'can', 'you', 'i', 'me', 'my', 'we', 'he', 'she', 'it', 'they', 'them',
            'is', 'are', 'am', 'was', 'were', 'be', 'been', 'being',
            'have', 'has', 'had', 'do', 'does', 'did', 'will', 'would', 'could', 'should',
            'the', 'a', 'an', 'and', 'or', 'but', 'in', 'on', 'at', 'to', 'for', 'of', 'from', 'with', 'by',
            'suggest', 'show', 'find', 'give', 'get', 'have', 'recommend', 'help', 'want', 'need',
            'please', 'thanks', 'thank', 'hi', 'hello', 'hey', 'ok', 'okay',
            'price', 'pricing', 'cost', 'under', 'below', 'budget', 'product', 'products', 'site', 'shop', 'catalog', 'catalogue',
            'lowest', 'cheapest', 'most', 'reviewed', 'reviews', 'review', 'rated',
            'over', 'above', 'greater', 'greaterthan', 'more', 'than', 'higher',
            'rupee', 'rupees', 'inr', 'rs',
        ];

        // Remove punctuation and split into words
        $words = preg_split( '/[\s\-_,\.!?]+/', trim( $message_lower ), -1, PREG_SPLIT_NO_EMPTY );

        // Filter out stop words and keep only meaningful keywords
        $keywords = [];
        foreach ( $words as $word ) {
            $word = trim( $word );
            if ( ! empty( $word ) && preg_match( '/^[0-9]+(?:\.[0-9]+)?$/', $word ) ) {
                continue;
            }

            if ( ! empty( $word ) && strlen( $word ) > 2 && ! in_array( $word, $stop_words, true ) ) {
                $keywords[] = $word;
            }
        }

        // Return keywords joined by space (WooCommerce will search for all terms)
        return ! empty( $keywords ) ? implode( ' ', array_slice( $keywords, 0, 3 ) ) : '';
    }

    private function extract_max_price( $message ) {
        $patterns = [
            '/(?:under|below|less\s+than|upto|up\s*to)\s*(?:rs\.?|rupees?|inr|₹|\$)?\s*([0-9]+(?:\.[0-9]+)?)/i',
            '/(?:rs\.?|rupees?|inr|₹|\$)\s*([0-9]+(?:\.[0-9]+)?)/i',
            '/([0-9]+(?:\.[0-9]+)?)\s*(?:rs\.?|rupees?|inr|₹|\$)/i',
        ];

        foreach ( $patterns as $pattern ) {
            if ( preg_match( $pattern, $message, $matches ) ) {
                return (float) $matches[1];
            }
        }

        return null;
    }

    private function extract_min_price( $message ) {
        $patterns = [
            '/(?:over|above|greater\s*than|more\s*than|higher\s*than)\s*(?:rs\.?|rupees?|inr|₹|\$|₪)?\s*([0-9]+(?:\.[0-9]+)?)/i',
            '/(?:rs\.?|rupees?|inr|₹|\$|₪)\s*([0-9]+(?:\.[0-9]+)?)\s*(?:and\s*above|\+\s*$)/i',
        ];

        foreach ( $patterns as $pattern ) {
            if ( preg_match( $pattern, $message, $matches ) ) {
                return (float) $matches[1];
            }
        }

        return null;
    }

    private function looks_like_budget_query( $message_lower ) {
        return (bool) preg_match(
            '/(under|below|less than|upto|up to|budget|cheap|affordable|price|cost|rs\.?|rupees?|inr|₹|\$)/i',
            $message_lower
        );
    }

    private function looks_like_browse_products_request( $message_lower ) {
        return (bool) preg_match(
            '/\b(show|list|browse|view|see)\b.*\b(product|products|shop|catalog|catalogue)\b|\b(all|shop)\s+products?\b/i',
            $message_lower
        );
    }

    private function build_product_cards( array $products ) {
        $cards = [];

        foreach ( $products as $product ) {
            if ( ! $product instanceof WC_Product ) {
                continue;
            }

            $cards[] = [
                'id'              => $product->get_id(),
                'name'            => $product->get_name(),
                'description'     => wp_strip_all_tags( $product->get_short_description() ? $product->get_short_description() : $product->get_description() ),
                'price'           => wp_strip_all_tags( wc_price( (float) $product->get_price() ) ),
                'sale_price'      => $product->get_sale_price() !== '' ? wp_strip_all_tags( wc_price( (float) $product->get_sale_price() ) ) : '',
                'average_rating'  => (float) $product->get_average_rating(),
                'review_count'    => (int) $product->get_review_count(),
                'sku'             => $product->get_sku(),
                'stock_status'    => $product->is_in_stock() ? 'instock' : 'outofstock',
                'categories'      => wp_strip_all_tags( wc_get_product_category_list( $product->get_id(), ', ', '', '' ) ),
                'tags'            => wp_strip_all_tags( wc_get_product_tag_list( $product->get_id(), ', ', '', '' ) ),
                'attributes'      => $this->format_attributes( $product ),
                'image'           => wp_get_attachment_image_url( $product->get_image_id(), 'woocommerce_thumbnail' ),
                'url'             => $product->get_permalink(),
                'add_to_cart_url' => $this->get_card_add_to_cart_url( $product ),
            ];
        }

        return $cards;
    }

    private function get_card_add_to_cart_url( WC_Product $product ) {
        // Show Add to Cart only for directly purchasable simple products.
        if ( ! $product->is_type( 'simple' ) ) {
            return '';
        }

        if ( ! $product->is_purchasable() || ! $product->is_in_stock() ) {
            return '';
        }

        return $product->add_to_cart_url();
    }

    private function format_attributes( WC_Product $product ) {
        $result = [];

        foreach ( $product->get_attributes() as $attribute ) {
            if ( ! $attribute instanceof WC_Product_Attribute ) {
                continue;
            }

            $name = wc_attribute_label( $attribute->get_name() );
            if ( $attribute->is_taxonomy() ) {
                $terms = wp_get_post_terms( $product->get_id(), $attribute->get_name(), [ 'fields' => 'names' ] );
                $value = is_wp_error( $terms ) ? [] : $terms;
            } else {
                $value = $attribute->get_options();
            }

            $result[] = [
                'name'  => $name,
                'value' => implode( ', ', array_map( 'sanitize_text_field', (array) $value ) ),
            ];
        }

        return $result;
    }

    private function fallback_message( array $products, $message, $no_api = false ) {
        $base = $no_api
            ? 'AI API key is not configured yet. Here are products that may help:'
            : get_option( 'acosmaia_fallback_response', 'Sorry, I am unable to answer right now. Please contact support.' );

        if ( empty( $products ) ) {
            return $base . ' I could not find matching products for: ' . $message;
        }

        return $base;
    }

    private function is_order_details_request( $message_lower ) {
        if ( ! is_string( $message_lower ) || '' === trim( $message_lower ) ) {
            return false;
        }

        return (bool) preg_match(
            '/\b(my\s+orders?|order\s+history|recent\s+orders?|recent\s+purchases?|purchase\s+history|order\s+details?|track\s+my\s+order|show\s+my\s+orders?|show\s+my\s+recent\s+purchase\s+history)\b/i',
            $message_lower
        );
    }

    private function build_current_user_order_details_message() {
        if ( ! function_exists( 'is_user_logged_in' ) || ! is_user_logged_in() ) {
            $login_url = function_exists( 'wc_get_page_permalink' ) ? wc_get_page_permalink( 'myaccount' ) : wp_login_url();
            $login_url = $login_url ? esc_url_raw( $login_url ) : '';

            return $login_url
                ? 'Please log in to view your order details: ' . $login_url
                : 'Please log in to view your order details.';
        }

        $current_user_id = get_current_user_id();
        if ( $current_user_id <= 0 || ! function_exists( 'wc_get_orders' ) ) {
            return 'Unable to load your order details right now.';
        }

        $orders = wc_get_orders( [
            'customer_id' => $current_user_id,
            'limit'       => 5,
            'orderby'     => 'date',
            'order'       => 'DESC',
            'return'      => 'objects',
        ] );

        if ( empty( $orders ) ) {
            return 'No orders found for your account.';
        }

        $lines = [ 'Your recent orders:' ];
        foreach ( $orders as $order ) {
            if ( ! $order instanceof WC_Order ) {
                continue;
            }

            $order_number = '#' . sanitize_text_field( (string) $order->get_order_number() );
            $order_date = $order->get_date_created();
            $date_text = $order_date instanceof WC_DateTime ? $order_date->date_i18n( get_option( 'date_format', 'Y-m-d' ) ) : '';
            $status = sanitize_text_field( wc_get_order_status_name( $order->get_status() ) );
            $total = wp_strip_all_tags( $order->get_formatted_order_total() );
            $item_count = (int) $order->get_item_count();

            $line = sprintf(
                '%s | %s | %s | %s | %d item%s',
                $order_number,
                $date_text !== '' ? $date_text : 'Date unavailable',
                $status !== '' ? $status : 'Unknown status',
                $total !== '' ? $total : 'Total unavailable',
                $item_count,
                $item_count === 1 ? '' : 's'
            );

            $lines[] = $line;
        }

        if ( 1 === count( $lines ) ) {
            return 'No orders found for your account.';
        }

        if ( function_exists( 'wc_get_account_endpoint_url' ) ) {
            $orders_url = wc_get_account_endpoint_url( 'orders' );
            if ( is_string( $orders_url ) && $orders_url !== '' ) {
                $lines[] = 'View all orders: ' . esc_url_raw( $orders_url );
            }
        }

        return implode( "\n", $lines );
    }
}