Faster use of procs for divine insight

[Contemptuous]

Hello- my first actual post on these boards. I am trying to make a macro, and i need help- i have searched and done my best but i can't seem to manage it.

when i hit the macro- if my target is an ally is should cast a spell on them (power word shield) and if my target is an enemy (such as a boss i am dpsing as a disc healer) it casts shield on my target's target.

Any clues?

[aggixx]

#showtooltip Power Word: Shield
/cast [help, nodead][@targettarget, help, nodead] Power Word: Shield