<?php

namespace Awas\AdvancedSearch\Search;

class QueryBuilder
{
    private $container;

    public function __construct(\Awas\AdvancedSearch\Core\Container $container)
    {
        $this->container = $container;
    }
    /**
     * Builds the SQL query for the search engine.
     *
     * @param string $keyword
     * @param array $settings
     * @return string
     */
    public function build_query($keyword, $settings = [], $category = '')
    {
        global $wpdb;
        $table_name = $wpdb->prefix . 'awas_search_index';
        
        $keyword = sanitize_text_field($keyword);
        
        // 1. Stop Words Filtering
        $keyword = \Awas\AdvancedSearch\Core\Helper::sanitize_and_tokenize($keyword, $settings);
        
        // Settings defaults
        $max_results = isset($settings['logic']['max_results']) ? absint($settings['logic']['max_results']) : 10;
        $fuzzy = isset($settings['logic']['fuzzy_match']) ? (bool) $settings['logic']['fuzzy_match'] : true;
        
        $where = [];
        $where[] = $wpdb->prepare("status = %s", 'publish');

        // 2. Multilingual Support (WPML / Polylang)
        if (!empty($settings['advanced']['multilingual'])) {
            $lang = apply_filters('wpml_current_language', null);
            if (!$lang && function_exists('pll_current_language')) {
                $lang = pll_current_language('slug');
            }
            // Some products might have empty lang if created before WPML, so we allow empty or matched lang
            if ($lang) {
                $where[] = $wpdb->prepare("(lang = %s OR lang = '')", $lang);
            }
        }

        if (!empty($category)) {
            // Since our search_index table doesn't have a specific category column right now,
            // and we stored categories in the 'search_terms', we can enforce that the category
            // slug or name exists in the search_terms for a simple implementation.
            // Ideally, we'd join wp_term_relationships, but for performance, we can just do:
            $cat_term = get_term_by('slug', sanitize_text_field($category), 'product_cat');
            if ($cat_term) {
                $where[] = $wpdb->prepare("search_terms LIKE %s", '%' . $wpdb->esc_like($cat_term->name) . '%');
            }
        }

        // 3. Synonyms
        $search_keywords = [$keyword];
        if (!empty($settings['advanced']['synonyms'])) {
            $synonyms_raw = explode("\n", $settings['advanced']['synonyms']);
            foreach ($synonyms_raw as $rule) {
                $rule = explode('=', $rule);
                if (count($rule) === 2) {
                    $word1 = trim(strtolower($rule[0]));
                    $word2 = trim(strtolower($rule[1]));
                    $word1_pattern = '/\b' . preg_quote($word1, '/') . '\b/';
                    $word2_pattern = '/\b' . preg_quote($word2, '/') . '\b/';
                    
                    if (preg_match($word1_pattern, $keyword)) {
                        $search_keywords[] = preg_replace($word1_pattern, $word2, $keyword);
                    } elseif (preg_match($word2_pattern, $keyword)) {
                        $search_keywords[] = preg_replace($word2_pattern, $word1, $keyword);
                    }
                }
            }
        }

        $search_keywords = array_unique(array_filter($search_keywords));
        
        if (empty($search_keywords)) {
            return "";
        }

        $all_search_conditions = [];
        
        foreach ($search_keywords as $kw) {
            $search_conditions = [];
            $words = array_filter(explode(' ', $kw));
            
            // Exact SKU Match (Highest priority)
            $search_conditions[] = $wpdb->prepare("sku = %s", $kw);

            // Exact Title Match
            $search_conditions[] = $wpdb->prepare("title LIKE %s", '%' . $wpdb->esc_like($kw) . '%');

            // Fuzzy matching logic on search_terms (FULLTEXT OR LIKE)
            if ($fuzzy && !empty($words)) {
                $like_conditions = [];
                foreach ($words as $word) {
                    $like_conditions[] = $wpdb->prepare("search_terms LIKE %s", '%' . $wpdb->esc_like($word) . '%');
                }
                $search_conditions[] = "(" . implode(" AND ", $like_conditions) . ")";
            } elseif (!empty($words)) {
                $search_conditions[] = $wpdb->prepare("search_terms LIKE %s", '%' . $wpdb->esc_like($kw) . '%');
            }
            
            $all_search_conditions[] = "(" . implode(" OR ", $search_conditions) . ")";
        }
        
        $where[] = "(" . implode(" OR ", $all_search_conditions) . ")";

        $where_sql = implode(" AND ", $where);

        // Calculate relevance: Exact SKU (100), Exact Title (50), Partial (10)
        $select = "
            object_id, 
            variation_id,
            title,
            sku,
            (
                IF(sku = '" . esc_sql($keyword) . "', 100, 0) +
                IF(title LIKE '%" . esc_sql($keyword) . "%', 50, 0)
            ) as relevance
        ";

        $sql = "SELECT $select FROM $table_name WHERE $where_sql ORDER BY relevance DESC, title ASC LIMIT $max_results";

        return $sql;
    }
}