using System;

 using System.Runtime.InteropServices;

 using System.Diagnostics;

 namespace Win32.Utils

 {

     /// <summary>

     /// Provide some utility functions for raw input handling.

     /// </summary>

     static class RawInput

     {

         /// <summary>

         /// 

         /// </summary>

         /// <param name="aRawInputHandle"></param>

         /// <param name="aRawInput"></param>

         /// <param name="rawInputBuffer">Caller must free up memory on the pointer using Marshal.FreeHGlobal</param>

         /// <returns></returns>

         public static bool GetRawInputData(IntPtr aRawInputHandle, ref RAWINPUT aRawInput, ref IntPtr rawInputBuffer)

         {

             bool success = true;

             rawInputBuffer = IntPtr.Zero;

             try

             {

                 uint dwSize = 0;

                 uint sizeOfHeader = (uint)Marshal.SizeOf(typeof(RAWINPUTHEADER));

                 //Get the size of our raw input data.

                 Win32.Function.GetRawInputData(aRawInputHandle, Const.RID_INPUT, IntPtr.Zero, ref dwSize, sizeOfHeader);

                 //Allocate a large enough buffer

                  rawInputBuffer = Marshal.AllocHGlobal((int)dwSize);

                 //Now read our RAWINPUT data

                 if (Win32.Function.GetRawInputData(aRawInputHandle, Const.RID_INPUT, rawInputBuffer, ref dwSize, (uint)Marshal.SizeOf(typeof(RAWINPUTHEADER))) != dwSize)

                 {

                     return false;

                 }

                 //Cast our buffer

                 aRawInput = (RAWINPUT)Marshal.PtrToStructure(rawInputBuffer, typeof(RAWINPUT));

             }

             catch

             {

                 Debug.WriteLine("GetRawInputData failed!");

                 success = false;

             }

             return success;

         }

         /// <summary>

         /// 

         /// </summary>

         /// <param name="hDevice"></param>

         /// <param name="deviceInfo"></param>

         /// <returns></returns>

         public static bool GetDeviceInfo(IntPtr hDevice, ref RID_DEVICE_INFO deviceInfo)

         {

             bool success = true;

             IntPtr deviceInfoBuffer = IntPtr.Zero;

             try

             {

                 //Get Device Info

                 uint deviceInfoSize = (uint)Marshal.SizeOf(typeof(RID_DEVICE_INFO));

                 deviceInfoBuffer = Marshal.AllocHGlobal((int)deviceInfoSize);

                 int res = Win32.Function.GetRawInputDeviceInfo(hDevice, Const.RIDI_DEVICEINFO, deviceInfoBuffer, ref deviceInfoSize);

                 if (res <= 0)

                 {

                     Debug.WriteLine("WM_INPUT could not read device info: " + Marshal.GetLastWin32Error().ToString());

                     return false;

                 }

                 //Cast our buffer

                 deviceInfo = (RID_DEVICE_INFO)Marshal.PtrToStructure(deviceInfoBuffer, typeof(RID_DEVICE_INFO));

             }

             catch

             {

                 Debug.WriteLine("GetRawInputData failed!");

                 success = false;

             }

             finally

             {

                 //Always executes, prevents memory leak

                 Marshal.FreeHGlobal(deviceInfoBuffer);

             }

             return success;

         }

         /// <summary>

         /// Fetch pre-parsed data corresponding to HID descriptor for the given HID device.

         /// </summary>

         /// <param name="device"></param>

         /// <returns></returns>

         public static IntPtr GetPreParsedData(IntPtr hDevice)

         {

             uint ppDataSize = 256;

             int result = Win32.Function.GetRawInputDeviceInfo(hDevice, Win32.Const.RIDI_PREPARSEDDATA, IntPtr.Zero, ref ppDataSize);

             if (result != 0)

             {

                 Debug.WriteLine("Failed to get raw input pre-parsed data size" + result + Marshal.GetLastWin32Error());

                 return IntPtr.Zero;

             }

             IntPtr ppData = Marshal.AllocHGlobal((int)ppDataSize);

             result = Win32.Function.GetRawInputDeviceInfo(hDevice, Win32.Const.RIDI_PREPARSEDDATA, ppData, ref ppDataSize);

             if (result <= 0)

             {

                 Debug.WriteLine("Failed to get raw input pre-parsed data" + result + Marshal.GetLastWin32Error());

                 return IntPtr.Zero;

             }

             return ppData;

         }

         /// <summary>

         /// 

         /// </summary>

         /// <param name="device"></param>

         /// <returns></returns>

         public static string GetDeviceName(IntPtr device)

         {

             uint deviceNameSize = 256;

             int result = Win32.Function.GetRawInputDeviceInfo(device, Win32.Const.RIDI_DEVICENAME, IntPtr.Zero, ref deviceNameSize);

             if (result != 0)

             {

                 return string.Empty;

             }

             IntPtr deviceName = Marshal.AllocHGlobal((int)deviceNameSize * 2);  // size is the character count not byte count

             try

             {

                 result = Win32.Function.GetRawInputDeviceInfo(device, Win32.Const.RIDI_DEVICENAME, deviceName, ref deviceNameSize);

                 if (result > 0)

                 {

                     return Marshal.PtrToStringAnsi(deviceName, result - 1); // -1 for NULL termination

                 }

                 return string.Empty;

             }

             finally

             {

                 Marshal.FreeHGlobal(deviceName);

             }

         }

     }

 }