[Request] Code that prevents a particular leader from declaring any sort of offensive war

[Homusubi]

I'm trying to make a civ (well, an alternate leader really) that has a Venice/Kongo style restriction on its behaviour, namely, being unable to declare war, whether that's a surprise war, a formal war, a joint war, a war from a troops-on-border warning, or whatever. They can, of course, still be attacked by other civs. However, I don't know anything about Lua, and I presume that's what's necessary for this sort of thing, if indeed it is possible at all.

Can anyone here make this sort of code work?