How to tie to Asp.Net Wep Api with Windows authorization, token authorization?

Question

API

Good day!
There is an Asp.Net Web Api service running on the intranet. Authorization via Windows Authentication.
There is a need to write an Internet site with user registration through the same Web Api. Those. in the service, part of the api will be available only on the intranet, and part - only via the Internet.
How to do it right, beautifully? How to combine windows and token authentication?