Stats: Reduxify fetching post likes

[youknowriad]

As a first step to resolve #10348 I'm creating a likes state subtree under posts.
This is also part of #5046

Nothing to test for now.

[matticbot]

Test live: https://calypso.live/?branch=add/stats/reduxify-likes

[timmyc]

This is looking great so far. I wasn't too familiar with the posts/<id>/likes endpoint so I did a bit of digging into the code behind it. The API response also returns ( as I'm sure you know, but putting here for future me 😆 ) found, i_like, site_ID, and post_ID - the last two items are a bit redundant, but I suppose would be of use in a batch operation. Endpoint documentation here.

Currently, in this state implementation, we are only persisting the likes array and not the other data. The problem being, the code that powers the likes array has a hard limit of 90 records on the query - it also appears that the default logic will only return likees that have gravatars via has_gravatar.

So if we have a post that has > 90 likes, or is liked by users without gravatars, the data we are using in the state tree won't properly reflect the total number of likes. The found attribute in the response though is a raw COUNT of all users who have liked a post, no LIMIT or gravatar requirement.

As such, I think we should probably go ahead and persist the entire response object in the state tree - omitting site_ID and post_ID because they are both comprised in the tree. This would allow us to display the proper number of likes on a given post, and potentially a future component that uses this part of the state tree would also want access to i_like. Do you think that is a good idea too?

[timmyc]

Should this test description read should set post ID to false if request finishes unsuccessfully?

[youknowriad]

Good catch @timmyc I naively supposed all the likes will be returned.
I guess this also answers the question of whether we should limit the avatars displayed since we would get a maximum of 90 in any circumstance.

[youknowriad]

updated in 4df3ac2 :)

[youknowriad]

I rebased the branch, do you think you'll have time to take a look again @timmyc ?

[timmyc]

Looking good now! Thanks for updating that to accommodate all the data.