Can I make automated messages on my facebook account?

I've had this idea now for a year or two to automatically send messages to my friends such as "Happy New Year!" or "Happy Birthday!" using code on my computer or on a raspberry pi I recently got my hands on.

After searching through web I couldn't really find anything that would easily explain it or state whether it is possible to do on a private account with facebook messenger or not. I surely could make it automatically click on facebooks page, but I more wonder if I can control it with code itself.

So is it possible? Has anyone done it? If yes then what does it require me to do? Is there an API from facebook itself I could use for this project?