Writing plugin for IDL-like language

I have a simple IDL-like language that I run through a processor to produce java classes that I can then reference from the java world.

I'd like to write a simple plugin to make my life easier in IDEA and I'd like to bounce ideas with the OpenAPI Gods to see what the right approach could be.

Ideally:
1. when opening up the project fresh, the java references to the not-yet-generated classes would not be red. Instead, they would point to the right spot in the IDL-like file.
2. when compiling the project, my plugin would step in to generate the .java classes (if necessary) before the compiler takes over; the classes would be generated in a location that isn't the normal source tree and doesn't interfere with source control (i.e. IDEA doesn't ask me to add them to source control and such.)


Is 1 feasible, or should I expect to have to generate the .java classes before all the references can be resolved?

What is a good location for the generated classes?

Would there be a plugin out there that does something roughly similar that I could draw inspiration from?

I've been away from plugin development for several years now so it's like starting all fresh again..

Thanks

  Vince.