Mouseover Macro Help

I want to create a macro that will show one spell when I have a hostile target, but show a different spell whenever I mouseover a friendly target/unit frame or do not have a target at all, regardless of whether I’m targeting an enemy or not.

So here’s what I want to achieve with this macro:
I don’t have a target at all and my current spell is Healing Surge, I target an enemy and the spell changes to Lightning Bolt, then if I mouseover a friendly target it changes to Healing Surge – even if my current target is still hostile. I’m struggling to create the macro and I feel like its a simple solution, would appreciate help with this from you macro wizards.

This macro I’m trying to create is for my restoration shaman. I want have efficient macros that show damage spells when targeting a hostile, but will change to healing when I mouseover a friendly player or do not have a target at all. If you have any advice towards that or a suggestion please let me know.

#showtooltip
/cast [mod:alt,@player] [@mouseover,help,nodead] Healing Surge; [@mouseover,harm,nodead] [harm] Lightning Bolt; Healing Surge