Applied rule id in cart page

Display applied rule ID on cart page.

add_action('woocommerce_before_cart', function() {
    if(class_exists('\WDR\App\Controllers\DiscountCalculator')) {
        $applied_rules = \WDR\App\Controllers\DiscountCalculator::$applied_rules;
        $rule_ids = !empty($applied_rules) ? array_keys($applied_rules) : 0 ;
        print_r($rule_ids);
    }
}, 10);