I want to set up an identity server to centralize the authentication for multiple backend APIs (ASP.NET Web API mostly) and multiple clients (Web SPA, Xamarin Mobile and WPF PC-client). I preferably want to present the clients with a single OAuth2 token endpoint, where they can send the users credentials, together with the client_id and client_secret (plus realm etc) and get back a token (and refreshtoken) to use as a bearer-token when talking to the HTTP APIs.
The somewhat tricky part is I want the identity server to use ADFS to authenticate the identity against the users Active Directory account.
I've looked at Thinktecture IdentityServer v3, but I can't seem to find a way to allow the workflow of just using HTTP post to a token endpoint. The way it seems to work to me is to redirect the user to the authorize endpoint, which would require a webview in the non-web clients. Is there a way to achieve this without requiring a webview, just using a HTTP API?
Any links to examples of this, or possible other solutions will be greatly appreciated.