Requested WoW macro

Hello, I would like to have a kind of ‘travelform’-macro. The idea is to fly or swim, whatever is possible or to switch to travel form if I want to run away (in combat or non-flyzone). And additionally I want the same macro to cancel my flight form if I’m flying.

Basically the following conditions apply (in a kind of vb-language to make it clear):

If (flightform) then
/cancelform
else
{
if (nocombat, swimming) then
/cast swimming form
elseif (nocombat, flyablezone) then
/cast flight form
elseif
/cast travelform
end if
}
end if

I have startend and so far I have:
/cancelform [stance:5];/cast [swimming,nostance]!Aquatic Form;[outdoors,nocombat,flyable,nostance]!Swift Flight Form;[outdoors,nostance]!Travel Form;

But the biggest problem here is the condition to stop the macro after the cancelform if form is canceled!!

Thank you in advance.