Using custom IDP with WP
I got a client and they have a custom made IDP now they are moving to WordPress from Blogger and I made the full setup for the new WP site. Now they want the logins to be made from the IDP and not in the WP site. I tried many plugins but none of them worked. As I have some experience in plugin development I am planning to create a new plugin. But I have some doubts hope someone would help me.
When a user clicks login in WP he should be redirected to the IDP login page with some identifiers. How can I do this? (I guess customizing wp-login will work but I’m unable to find any hook for that)
Then once the user successfully logs-in in the IDP the user is redirected to a Callback URL with some identifiers. How can I create a callback page? Which hooks should I use?
Finally after the user reaches the callback page the script communicates with the server and gets the credentials for logging in. Here how to check if the user is already registered in WP (that is already logged-in at least once) and how to register if not. If yes how to login the user.
Thanks in advance!!!