(Swift 3,4,5...) 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.

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func chilkatTest() {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let imap = CkoImap()!

    // Connect to your IMAP server and authenticate..
    imap.ssl = true
    imap.port = 993
    var success: Bool = imap.connect("imap.mail.us-west-2.awsapps.com")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    success = imap.login("myLogin", password: "myPassword")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    // Select a mailbox
    success = imap.selectMailbox("Inbox")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    // Search for all message having the letter 'a' somewhere in the Subject,
    // and return the messages as JSON.
    var json: CkoJsonObject? = imap.threadCmd("REFERENCES", charset: "UTF-8", searchCriteria: "SUBJECT a", bUid: true)
    if imap.lastMethodSuccess == false {
        print("\(imap.lastErrorText!)")
        return
    }

    // 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..

    var numThreads: Int = json!.size(ofArray: "threads").intValue
    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:
    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.
    print("Following the 2nd top level thread...")
    var arr: CkoJsonArray? = json!.array(of: "threads[1]")
    var threadSize: Int = arr!.size.intValue
    var i: Int = 0
    while i < threadSize {
        // Do we have an array or integer at this position?
        if arr!.typeAt(i).intValue == 4 {
            // This is a sub-array.
            var subArr: CkoJsonArray? = arr!.array(at: i)
            arr = nil
            // Follow the sub-array starting at the 1st position..
            arr = subArr
            i = 0
            threadSize = arr!.size.intValue
        }
        else {
            // Must be a single integer.
            print("\(arr!.int(at: i).intValue)")
            i = i + 1
        }

    }

    json = nil

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

}