Conditional Spell macro

[Taoth]

Hey all, i'm looking to make a conditional macro and wondering if what I want is possible.

What I want the macro to be able to do is to cast Wind Shear on an arena1-3 target that is not my focus or my current target. Meaning that if I have arena1 targetted and arena2 on focus, it'll shear arena3, and then if say 20 seconds later I switch my focus to arena3 and then it'll shear arena2.

I thought "/cast [@arena#, notarget, nofocus] Wind Shear" would work but target and focus aren't conditionals >.<

Anyone know any conditionals that would prevent the cast if the intended arena# in the line was either my current target or focus?