(Visual Basic 6.0) IMAP Search with THREAD Semantics

Demonstrates how to search an IMAP mailbox and return message numbers grouped together in parent/child relationships based on which messages are replies to others.

Note: This example requires Chilkat v9.5.0.77 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim imap As New ChilkatImap

' Connect to your IMAP server and authenticate..
imap.Ssl = 1
imap.Port = 993
Dim success As Long
success = imap.Connect("imap.mail.us-west-2.awsapps.com")
If (success <> 1) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

success = imap.Login("myLogin","myPassword")
If (success <> 1) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' Select a mailbox
success = imap.SelectMailbox("Inbox")
If (success <> 1) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' Search for all message having the letter 'a' somewhere in the Subject,
' and return the messages as JSON.
Dim json As ChilkatJsonObject
Set json = imap.ThreadCmd("REFERENCES","UTF-8","SUBJECT a",1)
If (imap.LastMethodSuccess = 0) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' The IMAP server will return a raw response with a format such as this:  (2)(3 6 (4 23)(44 7 96))

' In tree form, it's like this:
' 
'             -- 2
'             -- 3
'                 \-- 6
'                    |-- 4
'                    |      \-- 23
'                    |
'                    |-- 44
'                               \-- 7
'                                       \-- 96
' 

' It means there are 2 main threads returned, but the 2nd thread splits into two sub-threads.
' In total, we can think of it as 3 threads -- 2 main threads (with no parents) and one sub-thread w/ a parent.
' 
' - The 1st thread contains the message 2, and has no parent thread.
' - The 2nd thread contains the messages 3, 6, 4, 23, and has no parent thread.
' - The 3rd thread contains the messages 44, 7, 96 and the parent thread is message 6.
' 

' (Yes, this is all highly confusing...)

' Chilkat will return the above sample response as JSON that looks like this:

' {
'   "threads": [
'     [2],
'     [3, 6, [4, 23], [44, 7, 96]]
'   ]
' }
' 

' Use this online tool to generate parsing code from sample JSON: 
' Generate Parsing Code from JSON
' In this case, the online tool can help you get a feel for how to write the JSON parsing code..

Dim numThreads As Long
numThreads = json.SizeOfArray("threads")
Debug.Print "The total number of top-level threads is " & numThreads

' Let's say we wanted to get the messages in the thread 3, 6, 4, 23.
' We always follow the 1st branch to the bottom, ignoring the other branches.
' For example, if we had  [3, 5, [4, 23, [55, 56, 57], [68, 69]], [44, 7, 96]]
' then the thread would be 3, 5, 4, 43, 55, 56, 57

' For testing, let's substitute the response from the IMAP server with this sample:
success = json.Load("{""threads"": [[2], [3, 5, [4, 23, [55, 56, 57], [68, 69]], [44, 7, 96]]]}")

' Begin with the 2nd top-level thread, which is at index 1.
Debug.Print "Following the 2nd top level thread..."
Dim arr As ChilkatJsonArray
Set arr = json.ArrayOf("threads[1]")
Dim threadSize As Long
threadSize = arr.Size
Dim i As Long
i = 0
Do While i < threadSize
    ' Do we have an array or integer at this position?
    If (arr.TypeAt(i) = 4) Then
        ' This is a sub-array.
        Dim subArr As ChilkatJsonArray
        Set subArr = arr.ArrayAt(i)

        ' Follow the sub-array starting at the 1st position..
        Set arr = subArr
        i = 0
        threadSize = arr.Size
    Else
        ' Must be a single integer.
        Debug.Print arr.IntAt(i)
        i = i + 1
    End If

Loop

' The output is:
' 
' Following the 2nd top level thread...
' 3
' 5
' 4
' 23
' 55
' 56
' 57