I am looking for a module to sell items to specific customers which is used variety here from Iraq like the one below.

the customer may order 5 different products with different Qty as per our agreement with each product they have specific free items and also may have an extra discount with the total amount of the order, for example, Customer A has a discount program with order each 10 pcs of each product they will get 20% free product and with the total order they have 5% discount. 

Product 1 Ordered 10 units with a total amount 130$

Product 2 Order 30 Units with a total amount 330$

free items of Product 1 will be 2 units.

free items of product 2 will be 6 units.

the total invoice will be 460$ 

discount on the whole order is 23$

total after discount is 437 $

regarding the discount and loyalty is available is a different basic which I looking for.