Help with macro

[OttoFrinta]

Hi, could I pls ask for your help?

I wanted to mouseover my heals, without getting rid of autocast when my target is enemy or no target. When my target is friend, cast on friend, when I have a mouseover target, target mouseover target.

I found this solution:

/cmcast Lesser Heal
/script if UnitIsFriend("player", "target") then CastSpellByName("Lesser Heal"); else CastSpellByName("Lesser Heal", 1); end

Now I wonder if it is possible to also add help/harm effect to it while sacrificing the self cast, so:

If target is enemy, cast Power Word: Pain
If target is friend, cast Power Word: Shield
If mouseover target is enemy, cast Power Word: Pain (optional)
If mouseover target is friend, cast Power Word: Shield
If shift modifier is pressed, cast Power Word: Shied on self (optional)

I have absolutely no Idea how to do it or if it can be done, but you would have my eternal gratitude if you were able to create it!!!