Add the missing functions required for the WPCOM OAuth flow.

[jorgemd24]

Changes proposed in this Pull Request:

Closes part of #2146

Currently, in order to authorize a WPCOM App from a Jetpack site, the Jetpack plugin is required because the jetpack-connection lacks some essential functions necessary for a successful OAuth Flow. The Jetpack team is contemplating the inclusion of these functions in the jetpack-connection package. However, until that happens, we rely on these functions to enable the connection of any WPCOM App.

This PR copies the missing functions from Jetpack to this extension, allowing the complete OAuth flow to be executed without installing the Jetpack plugin. This PR is based on an experimental branch that I created. However, that branch was primarily intended to demonstrate the feasibility of authorizing a WPCOM app by simply copying functions and did not validate the Jetpack signature.

In essence, this PR adds all the necessary functions so that in the event that jetpack-connection doesn't incorporate these functions, we can use our version.

See more context here: pcTzPl-1SM-p2#comment-2672

Screenshots:

Detailed test instructions:

1. If you currently have Jetpack installed, remove the plugin to verify that OAuth functions correctly without it.
2. If your site is not connected, you can establish a connection with WPCOM. To do so, please visit the following link: wp-admin/admin.php?page=connection-test-admin-page
3. If you don't already have a WPCOM App, please refer to this link (https://developer.wordpress.com/apps/) to create one.
4. Proceed to authorize the WPCOM App that you've just created. For example, you can use a URL like this: https://public-api.wordpress.com/oauth2/authorize?client_id=YOUR_CLIENT_ID&redirect_uri=YOUR_REDIRECT_URI&response_type=code&blog=YOUR_BLOG_ID&scope=posts
5. Once you click the "approve" button, you will be redirected to your site, where you will need to log in. After that, you will be redirected once more to the redirect URI of your WPCOM app. In the URL, you will find the code that can be used to generate the token.
6. If you obtain the code, it indicates that the flow is functioning as intended. If you wish, you can also get a token by following the guidelines provided here: https://developer.wordpress.com/docs/oauth2/.

Additional details:

Changelog entry

Add - Missing functions for the WPCOM OAuth flow

[puntope]

Hi @jorgemd24 Thanks for making this progress with the project.

I created my APP but in order to test this PR I have some questions.

Proceed to authorize the WPCOM App that you've just created. For example, you can use a URL like this: https://public-api.wordpress.com/oauth2/authorize?client_id=YOUR_CLIENT_ID&redirect_uri=YOUR_REDIRECT_URI&response_type=code&blog=YOUR_BLOG_ID&scope=posts

1. Where can get the next variables?

YOUR_CLIENT_ID
YOUR_REDIRECT_URI
YOUR_BLOG_ID

2. When creating the WPCOM App in this link (https://developer.wordpress.com/apps/) do I need to fill in all the fields? Can it be done with a local domain? I would appreciate some indication in order to be sure I'm creating the APP the right way.

[puntope]

After reading the PR and P2 I found we are copying the functions from https://github.com/Automattic/jetpack/blob/trunk/projects/plugins/jetpack/class.jetpack.php

I think it would be useful to add that reference somewhere. I.e adding "Copied Code" or "Duplicated code" on each duplicated function in the class as well as in the main class PHPDOC. And also adding the link to the original jetpack class.

Otherwise, after this PR is approved, it might be difficult for other developers working on the code to know where this functions come from.

[jorgemd24]

Yep that's right I added a link to the Jetpack functions. See here: 1f7ca4c

[puntope]

This seems to be duplicated.

[puntope]

Hi @jorgemd24 The required functions from https://raw.githubusercontent.com/Automattic/jetpack/trunk/projects/plugins/jetpack/class.jetpack.php are copied correctly, and the translation domains replaced. So that part is ✅

Please help me with the smoke testing. See #2145 (comment) So I can be sure I'm fully testing this PR

[jorgemd24]

@puntope thanks for your time reviewing this PR!

Where can get the next variables?
YOUR_CLIENT_ID
YOUR_REDIRECT_URI
YOUR_BLOG_ID

When creating the WPCOM App in this link (https://developer.wordpress.com/apps/) do I need to fill in all the fields? Can it be done with a local domain? I would appreciate some indication in order to be sure I'm creating the APP the right way.

Once the WPCOM App is created you can get those variables from here: https://developer.wordpress.com/apps/

Your blog/site id can be found in /wp-admin/admin.php?page=connection-test-admin-page

When creating the WPCOM App in this link (https://developer.wordpress.com/apps/) do I need to fill in all the fields? Can it be done with a local domain? I would appreciate some indication in order to be sure I'm creating the APP the right way.

Yes, you need to fill in all details and the redirect URL can be http://localhost.

[puntope]

Hi @jorgemd24

Thanks a lot for the deeper explanation in regard the creation of WPCOM APP

I tested it and I was able to get the code in the URL after login in.

Also I tested with wrong params (i.e wrong URL) and I got the error as expected.

so LGTM ✅

[puntope]

Yes, you need to fill in all details and the redirect URL can be http://localhost/.

Notice this is not accurate, URL needs to be accessible or the next error appears: