Allow users to login to my site via their LinkedIn/Twitter/Facebook account once logged in say via LinkedIn they could also then authorise their Twitter and Facebook account as a optional login method. This would allow the user to authenticate via any of the three but end up with their user account on this site as the end result.
Also is necessary to use the authorisation they have provided to get basic user details (profile pic/name etc) and post status updates.
* If the user login to my website with Twitter, Facebook or Linkedin, and the account is not linked to any account on the website. The system has to offer create an account
* If the user login to the website with Twitter, Facebook or Linkedin, and the account is linked to an account. The login process should continue.
The code: [url removed, login to view]
Platform: Google App Engine
Web site of project: http://appengine.protoboard.cl