Mobile - Add new endpoint to get global styles settings through the REST API

[geriux]

What problem does this address?

In order to add support for Global Styles on the mobile editor, there should be an endpoint to be able to fetch this data through the REST API.

What is your proposed solution?

There's an opened PR with an exploration of this so we'd need to either continue that effort to use it as a reference.

[chipsnyder]

@geriux It looks like we might already have these values in the endpoint /wp/v2/themes?status=active Can we leverage this existing endpoint? Would that endpoint be missing any data that we might need?

https://github.com/WordPress/WordPress/blob/019bc2d244c4d536338d2c634419583e928143df/wp-includes/rest-api/endpoints/class-wp-rest-themes-controller.php#L17

[geriux]

@geriux It looks like we might already have these values in the endpoint /wp/v2/themes?status=active Can we leverage this existing endpoint? Would that endpoint be missing any data that we might need?

https://github.com/WordPress/WordPress/blob/019bc2d244c4d536338d2c634419583e928143df/wp-includes/rest-api/endpoints/class-wp-rest-themes-controller.php#L17

Hey @chipsnyder 👋

Unfortunately, that endpoint doesn't return the values that we need (contents of theme.json). I guess we could add the theme.json values but there are other things like __experimentalGlobalStylesUserEntityId logic which we'll need to bring any changes of the Global styles settings from the user.

So I think we should create a new endpoint that pulls the data from lib/global-styles.php, my only concern now is that it is filtering to only work if you're editing a site page so we'd need to figure out a way to make it work for both cases, on the web when you're editing your site (as it is now) and returning these settings without any gutenberg_is_edit_site_page checks through the REST API.

[chipsnyder]

Thanks @geriux for confirming. Diving in more I realized I was confusing theme_support with theme.json