using System;
using System.Diagnostics;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;

namespace BO
{
  /// <summary>
  /// 获取键盘输入或者USB扫描枪数据 可以是没有焦点 应为使用的是全局钩子
  /// USB扫描枪 是模拟键盘按下
  /// 这里主要处理扫描枪的值，手动输入的值不太好处理
  /// </summary>
  public class BardCodeHooK
  {
    public delegate void BardCodeDeletegate(BarCodes barCode);
    public event BardCodeDeletegate BarCodeEvent;

    //定义成静态，这样不会抛出回收异常
    private static HookProc hookproc;


    public struct BarCodes
    {
      public int VirtKey;//虚拟吗
      public int ScanCode;//扫描码
      public string KeyName;//键名
      public uint Ascll;//Ascll
      public char Chr;//字符


      public string OriginalChrs; //原始 字符
      public string OriginalAsciis;//原始 ASCII


      public string OriginalBarCode;  //原始数据条码


      public bool IsValid;//条码是否有效
      public DateTime Time;//扫描时间,


      public string BarCode;//条码信息   保存最终的条码
    }


    private struct EventMsg
    {
      public int message;
      public int paramL;
      public int paramH;
      public int Time;
      public int hwnd;
    }


    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    private static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);


    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    private static extern bool UnhookWindowsHookEx(int idHook);


    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    private static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam);


    [DllImport("user32", EntryPoint = "GetKeyNameText")]
    private static extern int GetKeyNameText(int IParam, StringBuilder lpBuffer, int nSize);


    [DllImport("user32", EntryPoint = "GetKeyboardState")]
    private static extern int GetKeyboardState(byte[] pbKeyState);


    [DllImport("user32", EntryPoint = "ToAscii")]
    private static extern bool ToAscii(int VirtualKey, int ScanCode, byte[] lpKeySate, ref uint lpChar, int uFlags);


    [DllImport("kernel32.dll")]
    public static extern IntPtr GetModuleHandle(string name);




    delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);
    BarCodes barCode = new BarCodes();
    int hKeyboardHook = 0;
    // string strBarCode = "";
    StringBuilder sbBarCode = new StringBuilder();







    private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam)
    {
      int i_calledNext = -10;
      if (nCode == 0)
      {
        EventMsg msg = (EventMsg)Marshal.PtrToStructure(lParam, typeof(EventMsg));
        if (wParam == 0x100)//WM_KEYDOWN=0x100
        {
          barCode.VirtKey = msg.message & 0xff;//虚拟吗
          barCode.ScanCode = msg.paramL & 0xff;//扫描码
          StringBuilder strKeyName = new StringBuilder(225);
          if (GetKeyNameText(barCode.ScanCode * 65536, strKeyName, 255) > 0)
          {
            barCode.KeyName = strKeyName.ToString().Trim(new char[] { ' ', '\0' });
          }
          else
          {
            barCode.KeyName = "";
          }
          byte[] kbArray = new byte[256];
          uint uKey = 0;
          GetKeyboardState(kbArray);


          //  if (barCode.KeyName.Equals("A") || barCode.KeyName.Equals("a"))
          //  {
          if (ToAscii(barCode.VirtKey, barCode.ScanCode, kbArray, ref uKey, 0))
          {
            barCode.Ascll = uKey;
            barCode.Chr = Convert.ToChar(uKey);
            barCode.OriginalChrs += " " + Convert.ToString(barCode.Chr);
            barCode.OriginalAsciis += " " + Convert.ToString(barCode.Ascll);
            barCode.OriginalBarCode += Convert.ToString(barCode.Chr);
          }
          // }


          TimeSpan ts = DateTime.Now.Subtract(barCode.Time);


          if (ts.TotalMilliseconds > 50)
          {//时间戳，大于50 毫秒表示手动输入
           
            sbBarCode.Remove(0, sbBarCode.Length);
            sbBarCode.Append(barCode.Chr.ToString());

            barCode.OriginalChrs = " " + Convert.ToString(barCode.Chr);
            barCode.OriginalAsciis = " " + Convert.ToString(barCode.Ascll);


            barCode.OriginalBarCode = Convert.ToString(barCode.Chr);

          }
          else
          {
            if ((msg.message & 0xff) == 13 && sbBarCode.Length > 3)
            {
              //回车
//              barCode.BarCode = barCode.OriginalBarCode.Replace("\r","").Replace("\t","");
              barCode.BarCode = barCode.OriginalBarCode;
              barCode.IsValid = true;
              sbBarCode.Remove(0, sbBarCode.Length);
            }
            sbBarCode.Append(barCode.Chr.ToString());
           
          }

          try
          {
            if (BarCodeEvent != null && barCode.IsValid)
            {

              //barCode.BarCode = barCode.BarCode.Replace("\b", "").Replace("\0","");  可以不需要 因为大于50毫秒已经处理
              //先进行 WINDOWS事件往下传
              i_calledNext = CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);




              BarCodeEvent(barCode);//触发事件

              barCode.BarCode = "";


              barCode.OriginalChrs = "";
              barCode.OriginalAsciis = "";
              barCode.OriginalBarCode = "";

            }

          }
          catch { }
          finally
          {
            barCode.IsValid = false; //最后一定要 设置barCode无效
            barCode.Time = DateTime.Now;
          }
        }
      }
      if (i_calledNext == -10)
      {
        i_calledNext = CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
      }
      return i_calledNext;
    }


    //安装钩子
    public bool Start()
    {
      if (hKeyboardHook == 0)
      {
        hookproc = new HookProc(KeyboardHookProc);

        //GetModuleHandle 函数 替代 Marshal.GetHINSTANCE
        //防止在 framework4.0中 注册钩子不成功
        var moduleName1 = Process.GetCurrentProcess().MainModule.ModuleName;
        var moduleName = Assembly.GetExecutingAssembly().ManifestModule.Name;
        IntPtr modulePtr = GetModuleHandle(moduleName1);


        //WH_KEYBOARD_LL=13
        //全局钩子 WH_KEYBOARD_LL
//          hKeyboardHook = SetWindowsHookEx(13, hookproc, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);


        hKeyboardHook = SetWindowsHookEx(13, hookproc, modulePtr, 0);
      }
      return (hKeyboardHook != 0);
    }


    //卸载钩子
    public bool Stop()
    {
      if (hKeyboardHook != 0)
      {
        return UnhookWindowsHookEx(hKeyboardHook);
      }
      return true;
    }


  }
}
