How to list all the variables in scope at a particular PSIStatement?

Hello,

I'd like to use PSI for Java to get a list of all the variables that are currently in scope at any given PsiStatement.

Example:

private static boolean isVariableDeclaredInsideBlock(PsiCodeBlock codeBlock, PsiVariable inputVar) {
    Collection<PsiVariable> blockInnerVariables = PsiTreeUtil.collectElementsOfType(codeBlock, PsiVariable.class);
    for (PsiVariable var : blockInnerVariables) {
        if (var.equals(inputVar))
            return true; //find what is in scope at this point? parameters+blockInnerVariables+var
    }
    int k = 10; 
    return false;
}

Any guidance would be greatly appreciated :)