HRESULT XTaskQueueTerminate(  
         XTaskQueueHandle queue,  
         bool wait,  
         void* callbackContext,  
         XTaskQueueTerminatedCallback* callback  
)  

void CreatingTaskQueue()
{
    XTaskQueueHandle queue;
    HRESULT hr = XTaskQueueCreate(XTaskQueueDispatchMode::ThreadPool, XTaskQueueDispatchMode::ThreadPool, &queue);
    if (FAILED(hr))
    {
        printf("Creating queue failed: 0x%x\r\n", hr);
        return;
    }

    SubmitCallbacks(queue);

    // Wait a while for the callbacks to run
    Sleep(1000);

    XTaskQueueTerminate(queue, true, nullptr, nullptr);
}

struct WorkData
{
    HWND hwnd;
    WCHAR text[80];
};

void CALLBACK WorkCompletion(void* context, bool cancel)
{
    WorkData* data = (WorkData*)context;

    if (!cancel)
    {
        SetWindowText(data->hwnd, data->text);
    }

    delete data;
}

void CALLBACK BackgroundWork(void* context, bool cancel)
{
    if (!cancel)
    {
        WorkData* data = new WorkData;
        data->hwnd = (HWND)context;

        if (GetTimeFormatEx(
            LOCALE_NAME_USER_DEFAULT, 0, nullptr, 
            nullptr, data->text, 80) == 0)
        {
            swprintf_s(data->text, L"Error : %d", GetLastError());
        }

        // Now take our formatted string and submit it as a completion callback
        XTaskQueueSubmitCallback(
            g_queue,
            XTaskQueuePort::Completion, 
            data, 
            WorkCompletion);
    }
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    HRESULT hr;

    switch (msg)
    {
    case WM_CREATE:
        
        // We will do work on the thread pool, but completion
        // callbacks should be manual so we can integrate them with
        // the message loop.

        hr = XTaskQueueCreate(
            XTaskQueueDispatchMode::ThreadPool,
            XTaskQueueDispatchMode::Manual,
            &g_queue);

        if (SUCCEEDED(hr))
        {
            hr = XTaskQueueRegisterMonitor(g_queue, hwnd, 
                [](void* context, XTaskQueueHandle, XTaskQueuePort port)
            {
                // If a new callback was submitted to the completion port, post a message
                // so we dispatch it in our message loop
                if (port == XTaskQueuePort::Completion)
                {
                    HWND hwnd = static_cast<HWND>(context);
                    PostMessage(hwnd, WM_QUEUE_COMPLETION, 0, 0);
                }
            }, &g_monitorToken);
        }

        if (FAILED(hr))
        {
            PostQuitMessage(1);
            return 0;
        }
        break;
      
    case WM_LBUTTONDOWN:
        hr = XTaskQueueSubmitCallback(
            g_queue,
            XTaskQueuePort::Completion,
            hwnd,
            BackgroundWork);

        if (FAILED(hr))
        {
            MessageBox(hwnd, L"Failed to submit callback.", L"Error", MB_OK);
        }
        break;

    case WM_QUEUE_COMPLETION:
        XTaskQueueDispatch(g_queue, XTaskQueuePort::Completion, 0);
        break;

    case WM_CLOSE:

        // Terminate the task queue.  When done, destroy our window.  The termination callback
        // is queued to the completion port, so it will already be on the UI thread.

        hr = XTaskQueueTerminate(g_queue, false, hwnd, [](void* context)
        {
            HWND hwnd = static_cast<HWND>(context);
            DestroyWindow(hwnd);
            XTaskQueueUnregisterMonitor(g_queue, g_monitorToken);
            XTaskQueueCloseHandle(g_queue);
        });

        if (SUCCEEDED(hr))
        {
            // Prevent DefWndProc from destroying our window because
            // the termination callback will do it.
            return 0;
        }
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        break;

    }

    return DefWindowProc(hwnd, msg, wParam, lParam);
}

void TestWndProc()
{
    WNDCLASS wndClass;
    ZeroMemory(&wndClass, sizeof(wndClass));
    wndClass.lpfnWndProc = WndProc;
    wndClass.lpszClassName = L"TestClass";
    wndClass.hInstance = GetModuleHandle(nullptr);
    wndClass.hbrBackground = GetSysColorBrush(COLOR_WINDOW);

    ATOM c = RegisterClass(&wndClass);

    HWND h = CreateWindow(L"TestClass", L"Window", 
        WS_OVERLAPPEDWINDOW | WS_VISIBLE, 
        10, 10, 300, 100, nullptr, nullptr, 
        GetModuleHandle(nullptr), 0);

    if (!h)
    {
        return;
    }

    MSG m;

    while (GetMessage(&m, nullptr, 0, 0))
    {
        TranslateMessage(&m);
        DispatchMessage(&m);
    }
}