(Swift 3,4,5...) Azure File Service: Upload Large File

Sample code to upload a large file to a directory in a share in the Azure File Service. A file is uploaded by first creating the file in the Azure share and then writing ranges of bytes to the file. Azure imposes a 4MB limit for each PUT to write a range. Files larger than 4MB need to be uploaded by making multiple "Put Range" calls. This example uploads a large file requiring multiple "Put Range" calls.

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func chilkatTest() {
    // Azure File Service Example: Upload a large file.  
    // See:  https://docs.microsoft.com/en-us/rest/api/storageservices/create-share
    // also see: https://docs.microsoft.com/en-us/rest/api/storageservices/put-range

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

    let rest = CkoRest()!

    // Connect to the Azure Storage Blob Service
    var bTls: Bool = true
    var port: Int = 443
    var bAutoReconnect: Bool = true
    // In this example, the storage account name is "chilkat".
    var success: Bool = rest.connect("chilkat.file.core.windows.net", port: port, tls: bTls, autoReconnect: bAutoReconnect)
    if success != true {
        print("\(rest.lastErrorText!)")
        return
    }

    // This example will upload a larger file.
    var localFilePath: String? = "qa_data/zips/somethingBig.zip"
    let fac = CkoFileAccess()!
    // Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
    // the size of the file as a string, then convert to an integer value.
    var szLocalFile: Int = fac.fileSize(localFilePath).intValue
    if szLocalFile < 0 {
        print("\(fac.lastErrorText!)")
        return
    }

    // Provide Azure Cloud credentials for the REST calls.
    let azAuth = CkoAuthAzureStorage()!
    azAuth.accessKey = "AZURE_ACCESS_KEY"
    // The account name used here should match the 1st part of the domain passed in the call to Connect (above).
    azAuth.account = "chilkat"
    azAuth.scheme = "SharedKey"
    azAuth.service = "File"
    // This causes the "x-ms-version: 2020-08-04" header to be automatically added.
    azAuth.xMsVersion = "2020-08-04"
    success = rest.setAuthAzureStorage(azAuth)

    // Note: The application does not need to explicitly set the following
    // headers: x-ms-date, Authorization.  These headers
    // are automatically set by Chilkat.

    // However, a few additional headers are required for the "Create File" operation:
    rest.addHeader("x-ms-type", value: "file")

    // This required header specifies the final size of the file (or the maximum size it can be).
    let sbFileSize = CkoStringBuilder()!
    sbFileSize.appendInt(szLocalFile)
    rest.addHeader("x-ms-content-length", value: sbFileSize.getAsString())

    // Send a PUT request to create the file (or replace the file if it already exists).
    // This will initialize the file in the Azure file storage.  To upload content, we'll need
    // to do the "Put Range" operation one or more times.

    // The following will create the file "somethingBig.zip" in the share "pip"
    var responseStr: String? = rest.fullRequestNoBody("PUT", uriPath: "/pip/somethingBig.zip")
    if rest.lastMethodSuccess != true {
        print("\(rest.lastErrorText!)")
        return
    }

    // When successful, the Azure File Service will respond with a 201 (Created) response status code,
    // with no XML response body.  If an error response is returned, there will be an XML response body.

    if rest.responseStatusCode.intValue != 201 {
        // Examine the request/response to see what happened.
        print("response status code = \(rest.responseStatusCode.intValue)")
        print("response status text = \(rest.responseStatusText!)")
        print("response header: \(rest.responseHeader!)")
        print("response body (if any): \(responseStr!)")
        print("---")
        print("LastRequestStartLine: \(rest.lastRequestStartLine!)")
        print("LastRequestHeader: \(rest.lastRequestHeader!)")
        return
    }

    print("Successfully created somethingBig.zip")

    // --------------------------------------------------------------------------------
    // Upload the file data...

    // Make sure the headers from the "Create File" operation are removed.
    rest.clearAllHeaders()

    // The x-ms-write header is required for each "Put Range" request.
    rest.addHeader("x-ms-write", value: "update")

    let sbRange = CkoStringBuilder()!
    let sbResponseBody = CkoStringBuilder()!
    let bdFileData = CkoBinData()!

    // Open the file.  We'll be reading and uploading in chunks..
    success = fac.open(forRead: localFilePath)
    if success != true {
        print("\(fac.lastErrorText!)")
        return
    }

    var numBytesLeft: Int = szLocalFile
    var curIndex: Int = 0
    while numBytesLeft > 0 {

        var chunkSize: Int = numBytesLeft
        // Azure allows for 4MB max chunks  (4 x 1024 x 1024 = 4194304)
        if chunkSize > 4194304 {
            chunkSize = 4194304
        }

        // The only tricky part here is to correctly add the x-ms-range header.
        // It will be formatted like this:
        // x-ms-range: bytes=0-759623
        sbRange.clear()
        sbRange.append("bytes=")
        sbRange.appendInt(curIndex)
        sbRange.append("-")
        sbRange.appendInt(curIndex + chunkSize - 1)

        // This replaces the header if it already exists..
        rest.addHeader("x-ms-range", value: sbRange.getAsString())

        // Read the next chunk from the local file.
        bdFileData.clear()
        success = fac.fileReadBd(chunkSize, binData: bdFileData)

        success = rest.fullRequestBd("PUT", uriPath: "/pip/somethingBig.zip?comp=range", binData: bdFileData, responseBody: sbResponseBody)
        if success != true {
            // This would indicate a failure where no response was received.
            print("\(rest.lastErrorText!)")
            return
        }

        // A 201 response indicates the chunk was uploaded.
        if rest.responseStatusCode.intValue != 201 {
            // Examine the request/response to see what happened.
            print("response status code = \(rest.responseStatusCode.intValue)")
            print("response status text = \(rest.responseStatusText!)")
            print("response header: \(rest.responseHeader!)")
            print("response body (if any): \(responseStr!)")
            print("---")
            print("LastRequestStartLine: \(rest.lastRequestStartLine!)")
            print("LastRequestHeader: \(rest.lastRequestHeader!)")
            return
        }

        print("Uploaded chunk from \(curIndex) to \(curIndex + chunkSize - 1)")

        curIndex = curIndex + chunkSize
        numBytesLeft = numBytesLeft - chunkSize
    }

    fac.fileClose()

    print("success.")

}