/**
 * BATCH PROCESSING SCRIPT (NO LOGGING): Updates WooCommerce sale dates for SIMPLE and VARIABLE products
 * from 2025-05-29 to 2025-05-30. Processes in batches.
 * Runs until all products are processed.
 */
function batch_no_log_update_all_product_sale_dates() {
    $script_option_prefix = 'batch_no_log_update_29_to_30_may_2025'; // Prefix for all options
    $batch_size = 50; // Number of products per batch

    // 1. Check if overall process is already complete
    $overall_complete_option = $script_option_prefix . '_overall_complete';
    if (get_option($overall_complete_option) === 'yes') {
        return; // Already done
    }

    // 2. Check for WooCommerce
    if (!function_exists('wc_get_products')) {
        return; // WooCommerce not active
    }

    // 3. Define Dates (UTC Timestamps)
    $target_day_start_timestamp_utc = strtotime('2025-05-29 00:00:00');
    $target_day_end_timestamp_utc   = strtotime('2025-05-29 23:59:59');
    $new_date_sale_to_utc_timestamp = strtotime('2025-05-30 23:59:59');

    $simple_complete_option = $script_option_prefix . '_simple_complete';
    $simple_offset_option = $script_option_prefix . '_simple_offset';
    $variable_complete_option = $script_option_prefix . '_variable_complete';
    $variable_offset_option = $script_option_prefix . '_variable_offset';

    // --- Stage 1: Process Simple Products ---
    $simple_products_complete = get_option($simple_complete_option, 'no');
    if ($simple_products_complete !== 'yes') {
        $current_offset_simple = (int) get_option($simple_offset_option, 0);

        $simple_products_args = [
            'type'   => 'simple',
            'limit'  => $batch_size,
            'offset' => $current_offset_simple,
            'status' => 'publish',
            'orderby'=> 'ID',
            'order'  => 'ASC',
        ];
        $simple_products = wc_get_products($simple_products_args);

        if (empty($simple_products)) {
            update_option($simple_complete_option, 'yes');
            $simple_products_complete = 'yes';
        } else {
            foreach ($simple_products as $product) {
                /** @var WC_Product_Simple $product */
                $date_on_sale_to_obj = $product->get_date_on_sale_to('edit');
                $current_sale_to_ts_utc = 0;

                if ($date_on_sale_to_obj instanceof WC_DateTime) {
                    $current_sale_to_ts_utc = $date_on_sale_to_obj->getTimestamp();
                } else {
                    continue;
                }
                
                $raw_sale_price_meta = $product->get_meta('_sale_price', true); // Still need this for the condition

                $has_sale_price = ($raw_sale_price_meta !== '' && $raw_sale_price_meta !== null);
                $has_valid_current_sale_end_date_ts = ($current_sale_to_ts_utc > 0);
                $is_target_date = ($current_sale_to_ts_utc >= $target_day_start_timestamp_utc && $current_sale_to_ts_utc <= $target_day_end_timestamp_utc);

                if ($has_sale_price && $has_valid_current_sale_end_date_ts && $is_target_date) {
                    $product->set_date_on_sale_to($new_date_sale_to_utc_timestamp);
                    $product->save();
                }
            }
            update_option($simple_offset_option, $current_offset_simple + count($simple_products));
            wp_cache_flush(); // Flush cache after a batch
            return; // Exit after processing one batch of simple products
        }
    }

    // --- Stage 2: Process Variable Products ---
    $variable_products_complete = get_option($variable_complete_option, 'no');
    if ($simple_products_complete === 'yes' && $variable_products_complete !== 'yes') {
        $current_offset_variable = (int) get_option($variable_offset_option, 0);

        $variable_products_args = [
            'type'   => 'variable',
            'limit'  => $batch_size,
            'offset' => $current_offset_variable,
            'status' => 'publish',
            'orderby'=> 'ID',
            'order'  => 'ASC',
        ];
        $variable_products = wc_get_products($variable_products_args);

        if (empty($variable_products)) {
            update_option($variable_complete_option, 'yes');
            $variable_products_complete = 'yes';
        } else {
            foreach ($variable_products as $product_var_parent) {
                /** @var WC_Product_Variable $product_var_parent */
                $variations = $product_var_parent->get_children();

                if (empty($variations)) {
                    continue;
                }

                foreach ($variations as $variation_id) {
                    $variation_obj = wc_get_product($variation_id);

                    if (!$variation_obj || !$variation_obj->is_purchasable()) {
                        continue;
                    }
                    /** @var WC_Product_Variation $variation_obj */
                    
                    $raw_var_sale_price_meta = $variation_obj->get_meta('_sale_price', true);
                    $var_date_on_sale_to_obj = $variation_obj->get_date_on_sale_to('edit');
                    $current_var_sale_to_ts_utc = 0;

                    if ($var_date_on_sale_to_obj instanceof WC_DateTime) {
                        $current_var_sale_to_ts_utc = $var_date_on_sale_to_obj->getTimestamp();
                    } else {
                        continue;
                    }
                    
                    $var_has_sale_price = ($raw_var_sale_price_meta !== '' && $raw_var_sale_price_meta !== null);
                    $var_has_valid_current_sale_end_date_ts = ($current_var_sale_to_ts_utc > 0);
                    $var_is_target_date = ($current_var_sale_to_ts_utc >= $target_day_start_timestamp_utc && $current_var_sale_to_ts_utc <= $target_day_end_timestamp_utc);

                    if ($var_has_sale_price && $var_has_valid_current_sale_end_date_ts && $var_is_target_date) {
                        $variation_obj->set_date_on_sale_to($new_date_sale_to_utc_timestamp);
                        $variation_obj->save();
                    }
                }
            }
            update_option($variable_offset_option, $current_offset_variable + count($variable_products));
            wp_cache_flush(); // Flush cache after a batch
            return; // Exit after processing one batch of variable products (parents)
        }
    }

    // --- Stage 3: Finalization ---
    if ($simple_products_complete === 'yes' && $variable_products_complete === 'yes') {
        update_option($overall_complete_option, 'yes');
        update_option($overall_complete_option . '_timestamp', date('Y-m-d H:i:s T'));
        // Optionally delete offset and stage-complete options
        delete_option($simple_complete_option);
        delete_option($simple_offset_option);
        delete_option($variable_complete_option);
        delete_option($variable_offset_option);
    }
    wp_cache_flush();
}

// Ensure this is the ONLY action hook for this purpose. Remove/comment out others.
add_action('wp_loaded', 'batch_no_log_update_all_product_sale_dates');