VBA script for automatically indexing topics

Question

A big disadvantage with InDesign's indexing system is that you cannot automatically index all occurences of topics currently in the index.
Instead, you have to find an occurence of each topic in the document itself and go to the Index menus and then click New Page Reference...Add All, for each index topic individually.
To get around this, I have been trying to produce a VBA script to automatically index all occurrences in a document of the topics currently in the document index.
I have been using the MS Excel VBA development environment but find the definitions of the object model in the Excel VBA browser rather inadequate and ambiguous .
Is there a more thorough reference work for these?
The plan was to start by taking each individual topic in the index which I tried to access with something along the lines of:
MyDocument.Index.Topic(1)
This hasn't worked.
The plan then was to take each index topic and use it to find an occurence in the document of that topic and then use that occurence to invoke the New Page Reference...Add All option to index all occcurences of that selected term, using something like:
MyDocument.PageReferences.Add
Again, without success.
Any guidance or suggestions would be appreciated.

Answer 1

Dear Peter,
Many thanks for your posting, that was very helpful.
This is the state of the script so far (I have added a large number of MsgBox entries - these aren't needed, they are just for debugging purposes during development):
'VBA script which tries to work through all of the topics in the index and automatically index each occurence of them in the current text frame:
main
Function main()
Set MyInDesign = CreateObject("InDesign.Application.CS4")
If MyInDesign.Documents.Count > 0 Then
    Set MyDocument = MyInDesign.ActiveDocument
    Set MyPage = MyDocument.Pages.Item(1)
    Set MyTextFrame = MyPage.TextFrames.Item(1)
    Set MyStory = MyTextFrame.ParentStory
    Set MyIndex = MyDocument.Indexes(1)
    Set MyTopics = MyIndex.AllTopics
    MyIndexesCount = MyDocument.Indexes.Count
    MsgBox "Current indexes Count: " & MyIndexesCount
    MyIndexTopicsCount = MyTopics.Count
    MsgBox "Current index topics Count: " & MyIndexTopicsCount
    For i = 1 To MyTopics.Count Step 1 'work through the topics
MyIndexTerm=MyTopics(i)
MsgBox "Current indexes Topic: " & MyIndexTerm
'search for MyIndexTerm :
        'Clear Find preferences:
        MyInDesign.FindTextPreferences = idNothingEnum.idNothing
        'Set up search paramaters:
        If MyIndexTerm <> "" Then
            MyInDesign.FindTextPreferences.FindWhat = MyIndexTerm
            'Set search options:
            MyInDesign.FindChangeTextOptions.CaseSensitive = False
            MyInDesign.FindChangeTextOptions.IncludeFootnotes = False
            MyInDesign.FindChangeTextOptions.IncludeHiddenLayers = False
            MyInDesign.FindChangeTextOptions.IncludeLockedLayersForFind = False
            MyInDesign.FindChangeTextOptions.IncludeLockedStoriesForFind = False
            MyInDesign.FindChangeTextOptions.IncludeMasterPages = False
            MyInDesign.FindChangeTextOptions.WholeWord = False
            'Search for the string:
            Set MyFoundItems = MyDocument.FindText 'this ought to be limited to the Story, not the Document eg MyStory
         MsgBox "Found index terms:" & MyFoundItems.Count
            For j = MyFoundItems.Count To 1 Step -1
               MyTopics(i).PageReferences.Add MyFoundItems(j)
            Next
           'Clear preference:
            MyInDesign.FindTextPreferences = idNothingEnum.idNothing
            'Having found it, add page reference:
         'MyDocument.PageReferences.Add
        Else
            MsgBox "No search term specified"
        End If
Response=MsgBox ("Continue?", vbYesNo)
If Response = vbNo then
  Exit For
End If
   Next
'Set up Index options:
MyIndex.IndexOptions.Title = "Index"
MyIndex.IndexOptions(1).TitleStyle="Chapter Head"
MyIndex.IndexOptions(1).ReplaceExistingIndex = True
'Generate the index:
MyIndex.Generate
Else
    MsgBox ("Please open a document, select an object, and try again.")
End If
End Function
There are a couple of problem areas still:
1. Index terms appear to be added irrespective of whether or not that particular page reference already exists in the index.
This can result in duplicate page references under each topic - especially if the script is run several times.
Is there any way of avoiding these duplicate references?
2. I haven't yet suceeded in getting the script to generate the index - so far I've had to do it manually after the script has run.
The problem lies somewhere in the code to set up the index options and then generate the index.
3. It might be useful to be able to limit the indexing to the curent story rather than the whole document - but I haven't yet got it to do that.
Best wishes.