Additional Step for Authentication

Good Morning We have FreeRadius authenticating users via AD. We want to perform an additional step of Authorization based on "Time Allowed to Login" We have an API that will already check if the User is allowed in based on their login time. What documentation can I look at to create the script? Basically if FreeRadius checks AD and thats good....then to make the additional check against our API and then to respond to the NAS that logging in is allowed. Let me know and I will start to research. Thanks