We're developing a mobile application for a web site that uses Wordpress and exposes a REST API through the WP REST API plugin. We have very little prior experience with Wordpress.
One of the requirements is to implement a login via Facebook feature, so that users could log in either by using their login and password or by using Facebook. The normal login is currently done with Basic Authentication. However, I cannot figure out how to implement the Facebook login part.
This seems to partially answer my question: https://stackoverflow.com/questions/12065492/rest-api-for-website-which-uses-facebook-for-authentication
But it implies that we'll need an additional API for sending the user access token to the server and validating it on the server-side.