Date comparison, datediff not supported by wow lua?

[kestralcoppernickle]

Hello i'm working on my first addon and part of it requires me to compare two dates to see how long in the past a date is ("2 days ago" for example).
The game only monitors gametime so I am comparing systemdates.

But it seems that WoW LUA doesn't incorporate LUA's datediff function, as it's not recognised in my code.

Is there anyone who's made a date difference function himself that would be willing to share it? I have been trying all evening but i've not bene able to write one myself, as i'm unable to figure out the logic behind the comparison.

Thanks