Nowhere. I don't want WhatsApp to make some shlt on me.
QML files are in /usr/share/whatsup folder, protocol is not so different from yappari or mitakuuluu, except I have a lot of unused code I've never cleaned. The rest is just basic like reading folders, files, etc.
I'll clean it someday and maybe put on some private repo, but there's a lot to do and it's not a priority for me.