Opencart - How much amount customer saved in cart

customer_save_amount_cart.php

public function savedAmountInCart() {
	$this->load->model('catalog/product');
	$saved_amt = 0;
	foreach ($this->cart->getProducts() as $product) {
		$product_info = $this->model_catalog_product->getProduct($product['product_id']);

		$actual_price = 0;
		if ($this->customer->isLogged() || !$this->config->get('config_customer_price')) {
			$actual_price = $product_info['price'];
		}

		if ((float) $product_info['special']) {
			$p = $product_info['special'];
			$diff = $product['quantity'] * ($actual_price - $p);
			if ($diff > 0) {
				$saved_amt += $diff;
			}
		}
	}

	return $saved_amt;
}