using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using static WindowsFormsApplication1.Win32Api;
namespace WindowsFormsApplication1
{
    /**
     * c#钩子程序 键盘监控(拦截系统组合键)
     * */
    public class Win32Api
    {
        #region 常数和结构
        public const int WM_KEYDOWN = 0x100;

        public const int WM_KEYUP = 0x101;

        public const int WM_SYSKEYDOWN = 0x104;

        public const int WM_SYSKEYUP = 0x105;

        public const int WH_KEYBOARD_LL = 13;

        [StructLayout(LayoutKind.Sequential)] //声明键盘钩子的封送结构类型 

        public class KeyboardHookStruct
        {
            public int vkCode; //表示一个在1到254间的虚似键盘码 
            public int scanCode; //表示硬件扫描码 
            public int flags;
            public int time;
            public int dwExtraInfo;
        }

        #endregion
        #region Api

        public delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);

        //安装钩子的函数 
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);

        //卸下钩子的函数 
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern bool UnhookWindowsHookEx(int idHook);

        //下一个钩挂的函数 
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam);

        [DllImport("user32")]
        public static extern int ToAscii(int uVirtKey, int uScanCode, byte[] lpbKeyState, byte[] lpwTransKey, int fuState);

        [DllImport("user32")]
        public static extern int GetKeyboardState(byte[] pbKeyState);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern IntPtr GetModuleHandle(string lpModuleName);

        #endregion
    }

    public class KeyboardHook
    {
        int hHook;

        Win32Api.HookProc KeyboardHookDelegate;

        public event KeyEventHandler OnKeyDownEvent;

        public event KeyEventHandler OnKeyUpEvent;

        public event KeyPressEventHandler OnKeyPressEvent;

        /// <summary>
        /// 正在执行回车事件中
        /// </summary>
        public bool IsExecute = false;

        public KeyboardHook() { }

        /**
         * 设置钩子
         * */
        public void SetHook()
        {
            KeyboardHookDelegate = new Win32Api.HookProc(KeyboardHookProc);
            Process cProcess = Process.GetCurrentProcess();
            ProcessModule cModule = cProcess.MainModule;
            var mh = Win32Api.GetModuleHandle(cModule.ModuleName);
            hHook = Win32Api.SetWindowsHookEx(Win32Api.WH_KEYBOARD_LL, KeyboardHookDelegate, mh, 0);
        }

        /**
         * 卸载钩子
         * */
        public void UnHook()
        {
            Win32Api.UnhookWindowsHookEx(hHook);
        }

        /**
         * 拦截按键
         * nCode参数是钩子代码，钩子子程使用这个参数来确定任务，这个参数的值依赖于Hook类型。
         * wParam和lParam参数包含了消息信息，我们可以从中提取需要的信息。
         * */
        private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam)
        {
            
            if (nCode >= 0)
            {
                KeyboardHookStruct kbh = (KeyboardHookStruct)Marshal.PtrToStructure(lParam, typeof(KeyboardHookStruct));

                if (kbh.vkCode == 13&& IsExecute)
                {
                    return 1;
                }

            }
            return Win32Api.CallNextHookEx(hHook, nCode, wParam, lParam);
        }
    }
}