Custom plugin for Woocommerce

I need custom functionality/plugin created for Woocommerce. I need to implement a feature that allows a new customer to enter a code into a field, which then validates against a code format (not an exact code), and automatically "upgrades" them to a user role that gains a discount assigned to that role for the current checkout. I will use this free plugin to create a group called "10% discount" which can be used for this custom functionality: [login to view URL] This is overview of custom work required: - Add a text field to checkout below the password field, that is only shown when user checks "Create an account?", with a text label (see attached image "[login to view URL]"). - User enters code, clicks "Apply membership number", field validates that the code entered starts with "RAI" and is followed by a combination of any 7 numbers. Any 7 numbers - If code is not valid, an error message appears below the filed in red: "Sorry, that membership number is not valid" - If code is valid, field is replaced with message as shown in attached image "[login to view URL]", and a discount applied to the cart subtotal immediately (even though user does not yet have an account created). - If user were to uncheck "Create an account?" this discount would be removed. - Once user completes purchase, they are a permanent member of this member group with a permanent 10% discount unless removed from the group via the admin. ---------- The 10% discount can be hard coded, to a specific member group name, so no admin interface required. I hope this would make it much simpler, the only "funky" bit should be applying the discount for a new user before they've actually created an account, but please let me know when you get back to me about how this can be done and time/costs. Thanks.