How To Add A Gift From The Controller?

[lokai]

Hello everybody

 

I need to know how to add a product gift.

 

Actually, in OrderController override i have this:

if (...){
$Cart = $this->context->cart;
		$Cart->updateQty($quantity, $id_product, $id_product_attribute = null, $id_customization = false, $operator = 'up', $id_address_delivery = 0, $shop = null, $auto_add_cart_rule = true);}

But I need this product to be a gift or to be priced 0 without cart rules, any clue?

 

Thanks in advance

 

Edited February 14, 2016 by lokai (see edit history)