add_action('wp_ajax_bpu_ultra_update', function(){
    global $wpdb;
    if(!current_user_can('manage_options')) wp_send_json_error('No permission');

    $rows = isset($_POST['rows']) ? json_decode(stripslashes($_POST['rows']), true) : [];
    if(!$rows || !is_array($rows)) wp_send_json_error('Tušti duomenys');

    $mapping = isset($_POST['mapping']) ? json_decode(stripslashes($_POST['mapping']), true) : get_option('bpu_ultra_mapping',[]);
    $lookup_csv_col = $mapping['lookup_sku'] ?? '';
    if(!$lookup_csv_col) wp_send_json_error('Trūksta Lookup: SKU');

    $cancel_flag = get_option('bpu_ultra_cancel_flag', false);
    if($cancel_flag) wp_send_json_error('Importas sustabdytas');

    $batch_size = 200;
    $batches = array_chunk($rows, $batch_size);

    // Surenkame visus pa_pristatymo-laikas priskyrimus batchui
    $taxonomy_assignments = [];

    foreach($batches as $batch){
        $meta_cases = [];
        $post_ids = [];

        foreach($batch as $row){
            $sku_val = trim($row[$lookup_csv_col] ?? '');
            $sku_val = remove_utf8_bom($sku_val);
            $sku_val = preg_replace('/\x{00a0}/u', '', $sku_val);
            $sku_val = trim(mb_convert_encoding($sku_val, 'UTF-8', 'auto'));

            if($sku_val === '') {
                error_log("Tuščias SKU eilutėje: ".print_r($row,true));
                continue;
            }

            $pid = wc_get_product_id_by_sku($sku_val);
            if(!$pid){
                error_log("Produktas nerastas SKU: $sku_val");
                continue;
            }
            $post_ids[] = $pid;

            $stock_val = null;
            $rpesp_meta = [];

            foreach($mapping as $wc_field => $csv_col){
                if($wc_field === 'lookup_sku' || $csv_col === '') continue;

                $val = trim($row[$csv_col] ?? '');
                $val = remove_utf8_bom($val);
                $val = trim(mb_convert_encoding($val, 'UTF-8', 'auto'));
                $val = preg_replace('/\x{00a0}/u', '', $val);
                $val = str_replace(',', '.', $val);

                if($val === '') error_log("Tuščias laukas: SKU=$sku_val, field=$wc_field, csv_col=$csv_col");

                switch($wc_field){
                    case '_price':
                    case '_regular_price':
                        $meta_cases[$wc_field][$pid] = floatval($val);
                        break;

                    case '_stock':
                        $stock_val = intval($val);
                        break;

                    case '_alg_ean':
                        $ean = preg_replace('/\D/','',$val);
                        if($ean !== '') $meta_cases['_alg_ean'][$pid] = $ean;
                        break;

                    case 'esttime':
                        $rpesp_meta['esttime'] = $val !== null ? $val : '';
                        break;

                    case 'taxonomy:pa_pristatymo-laikas':
                        $taxonomy_assignments[$pid] = trim($val);
                        break;

                    default:
                        $meta_cases[$wc_field][$pid] = $val;
                        break;
                }
            }

            // Stock update
            if($stock_val !== null){
                $meta_cases['_stock'][$pid] = $stock_val;
                $meta_cases['_stock_status'][$pid] = $stock_val > 0 ? 'instock' : 'outofstock';
                $meta_cases['_manage_stock'][$pid] = 'yes';
            }

            // rpesp-meta-setting update
            if($rpesp_meta){
                $existing = get_post_meta($pid,'rpesp-meta-setting',true);
                $existing = maybe_unserialize($existing);
                if(!is_array($existing)) $existing = [];
                $merged = array_merge($existing, $rpesp_meta);
                $meta_cases['rpesp-meta-setting'][$pid] = maybe_serialize($merged);
                error_log("RPESP meta updated SKU=$sku_val: ".print_r($merged,true));
            }
        }

        // SQL update per CASE
        foreach($meta_cases as $meta_key => $cases){
            if(!$cases) continue;
            $ids = implode(',', array_map('intval', array_keys($cases)));
            $case_sql = [];
            foreach($cases as $pid => $val){
                if(is_numeric($val)) $case_sql[] = "WHEN $pid THEN $val";
                else $case_sql[] = "WHEN $pid THEN '".$wpdb->_real_escape($val)."'";
            }
            $case_sql = implode(' ', $case_sql);

            $wpdb->query("
                UPDATE {$wpdb->postmeta} 
                SET meta_value = CASE post_id 
                    $case_sql
                END
                WHERE meta_key = '$meta_key' AND post_id IN ($ids)
            ");
        }

        // Batch update post_modified
        if($post_ids){
            $ids_str = implode(',', array_map('intval', $post_ids));
            $wpdb->query("UPDATE {$wpdb->posts} SET post_modified=NOW() WHERE ID IN ($ids_str)");
        }
    }

    // ------------------------
    // pa_pristatymo-laikas batch update (tik produkto lygyje)
    // ------------------------
    if(!empty($taxonomy_assignments)){
        $taxonomy = 'pa_pristatymo-laikas';
        $attr_slug = 'pristatymo-laikas';

        $attributes = wc_get_attribute_taxonomies();
        $exists = false;
        foreach($attributes as $attr){
            if($attr->attribute_name === $attr_slug){ $exists = true; break; }
        }
        if(!$exists && function_exists('wc_create_attribute')){
            $attribute_id = wc_create_attribute([
                'name' => 'Pristatymo laikas',
                'slug' => $attr_slug,
                'type' => 'select',
                'order_by' => 'menu_order',
                'has_archives' => false
            ]);
            if($attribute_id && !taxonomy_exists($taxonomy)){
                register_taxonomy($taxonomy,'product',[
                    'label' => 'Pristatymo laikas',
                    'hierarchical' => false,
                    'public' => true,
                    'show_ui' => true,
                    'show_in_nav_menus' => false,
                    'show_admin_column' => true,
                    'rewrite' => ['slug'=>$attr_slug]
                ]);
            }
        }

        $term_slugs = [];
        foreach(array_unique($taxonomy_assignments) as $term_name){
            $term_slug = sanitize_title($term_name);
            if(!term_exists($term_slug,$taxonomy)){
                wp_insert_term($term_name,$taxonomy,['slug'=>$term_slug]);
            }
            $term_slugs[$term_name] = $term_slug;
        }

        foreach($taxonomy_assignments as $pid => $term_name){
            $term_slug = $term_slugs[$term_name];
            $term_id = $wpdb->get_var($wpdb->prepare("SELECT term_id FROM {$wpdb->terms} WHERE slug=%s", $term_slug));
            $term_tax_id = $wpdb->get_var($wpdb->prepare("SELECT term_taxonomy_id FROM {$wpdb->term_taxonomy} WHERE term_id=%d AND taxonomy=%s", $term_id, $taxonomy));

            if($term_tax_id){
                $wpdb->query($wpdb->prepare("
                    DELETE tr FROM {$wpdb->term_relationships} tr
                    JOIN {$wpdb->term_taxonomy} tt ON tr.term_taxonomy_id = tt.term_taxonomy_id
                    WHERE tr.object_id = %d AND tt.taxonomy = %s
                ", $pid, $taxonomy));

                $wpdb->insert($wpdb->term_relationships,[
                    'object_id'=>$pid,
                    'term_taxonomy_id'=>$term_tax_id
                ]);
            }

            $existing_attrs = get_post_meta($pid, '_product_attributes', true);
            if(!is_array($existing_attrs)) $existing_attrs = [];
            $existing_attrs[$taxonomy] = [
                'name' => $taxonomy,
                'value' => '',
                'position' => 0,
                'is_visible' => 0,
                'is_variation' => 0,
                'is_taxonomy' => 1
            ];
            update_post_meta($pid,'_product_attributes',$existing_attrs);
        }
    }

    wc_delete_product_transients();
    wp_send_json_success(['count'=>count($rows)]);
});