How can I add "dislike" button?

My issue is that there’s not a comprehensive api where I would access existing values. A la a plugin api. Looking at the Discourse github there’s a lot of files and for me, it’s kind of hard to traverse it looking for how ‘the like’ works when I don’t know the reference names even. Is it in the database? Is it an attribute? Very difficult to see, which of course is probably due to my inexperience but the fact remains plugin support and documentation seems severely lacking. Looking at the plugin guide it’s slanted towards admins customizations, instead of sitewide customizations. my whole point was if there is no access endpoint for “likes” where would I look to see the core functionality and extend it (especially when its more complicated than using handlebar outlet) ?