Add push notifications to a social rails app

You gotta do two different set of works, 1. Add Push notifications in our rails application, thr rails app is kind of a social app where user posts like amd comment amd other get notified. 2. Add a ranking system based on the total number of like, the user who have got the highest total number of likes till date will rand first the user less then that will be sevond and so on... ranking of all the users will be seen on a new page and there individual ranking will be shown in the profile page.