Adding Authorization Code Flow with Proof Key for Code Exchange (PKCE)

[martinmake]

I would start with a discussion about the user interface.
I've added an example for this feature so we can have the same context.

What do you think about it?

Should we use:

• pub enum AuthorizationFlow to choose between Authorization Flows, or
• builders/functions, or
• should it be inferred from secret: Option<String> (won't scale well with other Authorization Flows)?

[marioortizmanero]

Hi, sorry for not replying earlier. I wanted to read about the PKCE authentication process beforehand. Maybe we should re-think the authentication process? I didn't really like how it turned out in the rewrite because we need stuff like InvalidAuth to for example make sure the me endpoint isn't accessed by a client with the Client Credentials Flow. I was thinking that we could take advantage of Rust's features and only implement these endpoints for some flows and make to make it more type-safe with a different architecture.

I'll open a new issue soon with some ideas where we can discuss how to make it work.

[marioortizmanero]

This is being discussed at #173 now. Let me know what you think!

[marioortizmanero]

Closing this, as #173 is more or less accepted. Thanks for your help, @martinmake.

[marioortizmanero]

This shouldn't have been closed because PKCE was left as a TODO In that PR. Reopening.

[marioortizmanero]

Ah sorry! I thought I was in the issue #150 but this was the old PR. Nevermind.