using System;
using System.Runtime.InteropServices;

public static class TaskbarProgress
{
  public enum TaskbarStates
  {
    NoProgress = 0,
    Indeterminate = 0x1,
    Normal = 0x2,
    Error = 0x4,
    Paused = 0x8
  }

  [ComImport()]
  [Guid("ea1afb91-9e28-4b86-90e9-9e9f8a5eefaf")]
  [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
  private interface ITaskbarList3
  {
    // ITaskbarList
    [PreserveSig]
    void HrInit();
    [PreserveSig]
    void AddTab(IntPtr hwnd);
    [PreserveSig]
    void DeleteTab(IntPtr hwnd);
    [PreserveSig]
    void ActivateTab(IntPtr hwnd);
    [PreserveSig]
    void SetActiveAlt(IntPtr hwnd);

    // ITaskbarList2
    [PreserveSig]
    void MarkFullscreenWindow(IntPtr hwnd, [MarshalAs(UnmanagedType.Bool)] bool fFullscreen);

    // ITaskbarList3
    [PreserveSig]
    void SetProgressValue(IntPtr hwnd, UInt64 ullCompleted, UInt64 ullTotal);
    [PreserveSig]
    void SetProgressState(IntPtr hwnd, TaskbarStates state);
  }

  [Guid("56FDF344-FD6D-11d0-958A-006097C9A090")]
  [ClassInterface(ClassInterfaceType.None)]
  [ComImport()]
  private class TaskbarInstance
  {
  }

  private static ITaskbarList3 taskbarInstance = (ITaskbarList3)new TaskbarInstance();

  public static void SetState(IntPtr windowHandle, TaskbarStates taskbarState)
  {
    taskbarInstance.SetProgressState(windowHandle, taskbarState);
  }

  public static void SetValue(IntPtr windowHandle, double progressValue, double progressMax)
  {
    taskbarInstance.SetProgressValue(windowHandle, (ulong)progressValue, (ulong)progressMax);
  }
}