You can get WoW's Lua and XML files directly from the game. That should give you a start. Unfortunately, I can not explain to you how this is done. Hopefully someone will chime in here with the information.
EDIT: OK, after a little searching I managed to find it.
https://wow.gamepedia.com/Viewing_Bl...interface_code
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Ahhhh, the vagueries of the aging mind. Wait.... What was I saying?
Carbonite <----- GitHub main module (Maps ONLY) download link. The other modules are also available on GitHub.
Carbonite-CLASSIC<----- GitHub link to Carbonite Classic. Thanks to ircdirk for this!