If formating as method argument

How do I format this so that it does what I want it to,

Day.find_by_month_and_year( [Date::today.month + 1 if !Date::today.month
== 12 else 1 end], [Date::today.year if !Date::today.month == 12 else
Date::today.year + 1 end] )

WHICH IS
to pass Day.find_by_month_and_year Date:today.month +1 if the month is
not december otherwise pass, 1, and to pass as the second argument
Date::today.year unless it IS the december, then I want it to pass it 1.

Sam???