Add like handler

[janboddez]

Adds basic support for incoming likes (see #235).

Probably needs to go through a couple more iterations before it could be merged! For instance, the ActivityPub plugin should maybe also get a pre_get_comments filter, similar to the Webmention plugin, so that these "likes" don't show up among "regular comments." Should be "rather easy" to implement.

But it's a "first draft."

I originally wanted to also add "repost" support but noticed an announce handler already exists. I'm going to have to check that out later. Maybe in a different PR.

Edit: This won't actually display, e.g., a facepile. Though it currently is compatible with IndieBlocks' Facepile block. I can imagine you'd want to eventually add a block of your own ...

Proposed changes:

• Adds a incoming like handler, and extends the existing undo handler to handle undoing of previous likes.

Note: I kept some of the actions from other reaction handlers and also set some comment meta to be able to later on display the like in a "facepile" kind of way. I also set some "dummy" content; feel free to change it in order to have it behave the same as, e.g., the Webmention plugin.

Other information:

• Have you written new tests for your changes, if applicable?

Testing instructions:

• Upload patched version
• Search for a local URL from, e.g., your Mastodon instance
• Like the corresponding post
• Watch the "like" appear as a new comment with comment type "like"
• Undo like
• Watch the "like" comment move to trash

[janboddez]

[T]he ActivityPub plugin should maybe also get a pre_get_comments filter, similar to the Webmention plugin, so that these "likes" don't show up among "regular comments."

On my personal site I don't need this, as I have my own such filter and block. But I thought I'd mention it.

[pfefferle]

@janboddez thanks a lot!

Do you think we need a UI/setting for that? It might be confusing if "Like" comments will simply show up in the comment section after the next update!?!

[janboddez]

Yes, I do think you will need a pre_get_comments filter to hide likes from the front end. And only show them through a shortcode or block (similar to IndieBlocks' Facepile block, or the Followers block), which could be added in a later version.

I'm not sure about showing/hiding them in WP-Admin. It could be confusing (for people who aren't familiar with, e.g., webmentions) to see "comments" in WP-Admin but not see them show up anywhere on the site. Hmm, maybe we need a completely separate WP-Admin (sub)menu for "likes"?

Or you could put the whole functionality behind a constant or something, so that "advanced" users (who might have their own means of displaying likes) can choose to enable it at their own risk.

[pfefferle]

@janboddez I refactored the code a bit and also added Announce support!

What do you think?

I am not very happy with the add_reaction method in the Interactions class, because I think this could be simplified a lot, but it should work for now!

Maybe we also hide it behind a feature flag, to run some tests and think about a nicer UI?

/cc @mattwiebe

[janboddez]

Cool!

Feature flag (like a PHP constant?) seems like a good idea! I can imagine most people wanting to have this disabled or at least not show the likes/reposts until there's something like a Facepile block (or some other way of displaying likes/reposts, like a counter of sorts). Not everyone will want to install IndieBlocks either, haha!

Are the register_comment_type() calls compatible with, e.g., the Webmention plugin? Won't it complain if the same type is registered "twice"? (Just asking, I honestly have no clue.)

[pfefferle]

Feature flag (like a PHP constant?) seems like a good idea! I can imagine most people wanting to have this disabled or at least not show the likes/reposts until there's something like a Facepile block (or some other way of displaying likes/reposts, like a counter of sorts). Not everyone will want to install IndieBlocks either, haha!

Yes!

Are the register_comment_type() calls compatible with, e.g., the Webmention plugin? Won't it complain if the same type is registered "twice"? (Just asking, I honestly have no clue.)

Kind of both! The ActivityPub version is stripped down a lot, so they are not completely identical, but they use the same vocabulary, so that there is no difference between a Webmention Like and an ActivityPub Like in the end.

[janboddez]

Silly question: Do we also need some custom CSS to make likes look "good" in WP's dashboard? Like in pfefferle/wordpress-webmention#396.

Didn't yet have a chance to test, but basically the question is: How do [likes and reposts] look (in the dashboard) with the Webmention plugin turned off?

[pfefferle]

The Webmention Plugin does not change the UI of the dashboard!

[janboddez]

Oh, I thought we added a bit of CSS to make like and reposts avatars behave.

[pfefferle]

You are totally right! I will add that!