Need to perform an action whenever an import is added (java/scala)

You can try implementing PsiTreeChangeListener (http://www.jetbrains.org/intellij/sdk/docs/basics/architectural_overview/psi_files.html#how-do-i-get-notified-when-psi-files-change) and determine whether change was "adding import" but it will be hard to implement it correctly, see javadoc on PsiTreeChangeEvent.

Thanks!
That’s one nasty javadoc :(
No other avenue you think I can pursue? I thought maybe to decorate a few of the import relates IntentAction classes and work from there (hacky and problematic but might be better than that javadoc warning)

Also I'm thinking of maybe attacking this in a few different directions and I'd really appreciate your thoughts/inputs:

1. Paste related- Catch cases where someone pastes an import into a Java/Scala file. Considering registering a "ContentChangedListener".

2. Import auto complete related hooks. I've been able to identify 3 relevant cases and I'm not sure yet about the hooks to get notified about them.

I know this doesn't catch the case where someone will manually type a fully qualified import but I'm willing to not handle this for now.

Do you think this is a relevant approach?

If so any chance you know which hooks I can use to work after these actions happen?

Thanks!

Import related actions:

Auto complete of an import

Auto complete of a class

Resolving a class

There are many ways an import statement could be inserted/modified/deleted in sources - including by updating from version control system, or external changes by some tool. etc etc.

So any attempt to "catch" changes outside of underlying Document/PSI will always be incomplete.

Thank you for all your help.

For others what I did was something like this:

case onDemandClassImport: PsiImportStatement if onDemandClassImport.isOnDemand =>
  None //I need the file and in an on demand import I don't have the file
case classImport: PsiImportStatement =>
  Some((classImport.getQualifiedName, classImport.resolve().getContainingFile))
case staticImport: PsiImportStaticStatement =>
  val targetClass = staticImport.resolveTargetClass()
  Some((targetClass.getQualifiedName, targetClass.getContainingFile))

To get the manual addition of an import working I did:

event.getNewChild.isInstanceOf[PsiJavaToken] && event.getNewChild.getParent.isInstanceOf[PsiImportStatementBase] && event.getNewChild.getNextSibling == null

Which means we have a token which belongs to a statement and there isn't a next sibling (before it's finished the next sibling exists and is an error sibling).

I'm now completely stuck on a scala ScImportStmt thing (getting the file where the imported class was declared in) but I should probably open a new thread about it. Thanks!