WordPress Post Like without Plugin

In muchad.com you can find love picture in every after post. This “post like” is integrated with my theme, medio theme.

I using Post Like system by Sven Hofmann’s, it’s pretty cool. This is the scenario:
When an anonymous user clicks the like button:
– User’s IP address is stored in the post’s meta as an array.
– These IP addresses are utilized to prevent anonymous users from liking posts more than once.
– Post like count is incremented +1 and stored in post meta.
When a registered user clicks the like button:
– WP User ID in the post’s meta as an array.
– Post like count is incremented +1 and stored in post meta.
– Post ID is stored as user meta.
– User like count is incremented +1 and stored as user meta.
 
If you want use it in your theme, you can read full tutorial in his website from this link or directly read his gist: