Add Product with Coupon (External/affiliate Product)

[SunnyCodeHub]

How do I add a coupon to product? Wordpress has placeholder to assign coupon. Please let me know

Product p = new Product() { name = "", description = "", price = "", sale_price = "", short_description = "", external_url ="", button_text = "Buy on Amazon", categories = "", images = "", type = "external", regular_price = "", };