using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace Common.system
{
    /// <summary>
    /// 键盘钩子
    /// 创建人：赵耀
    /// 创建时间：2020年9月11日
    /// </summary>
    public class KeyboardHookCommon
    {
        /// <summary>
        /// 全局按键按下
        /// </summary>
        public event KeyEventHandler KeyDownEvent;

        /// <summary>
        /// 窗口按键按下
        /// </summary>
        public event KeyPressEventHandler KeyPressEvent;

        /// <summary>
        /// 全局按键抬起
        /// </summary>
        public event KeyEventHandler KeyUpEvent;

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

        private static int _hKeyboardHook; //声明键盘钩子处理的初始值

        //值在Microsoft SDK的Winuser.h里查询
        /// <summary>
        /// 线程键盘钩子监听鼠标消息设为2，全局键盘监听鼠标消息设为13
        /// </summary>
        public const int WH_KEYBOARD_LL = 13;

        /// <summary>
        /// 声明KeyboardHookProcedure作为HookProc类型
        /// </summary>
        private HookProc _keyboardHookProcedure;

        /// <summary>
        /// 自己创建窗口按键 
        /// </summary>
        private const int WM_KEYDOWN = 0x100; //KEYDOWN

        /// <summary>
        /// 窗口按键抬起
        /// </summary>
        private const int WM_KEYUP = 0x101; //KEYUP

        /// <summary>
        /// 全局系统按键
        /// </summary>
        private const int WM_SYSKEYDOWN = 0x104; //SYSKEYDOWN

        /// <summary>
        /// 全局按键抬起
        /// </summary>
        private const int WM_SYSKEYUP = 0x105; //SYSKEYUP

        //键盘结构
        [StructLayout(LayoutKind.Sequential)]
        public class KeyboardHookStruct
        {
            public int vkCode; //定一个虚拟键码。该代码必须有一个价值的范围1至254
            public int scanCode; // 指定的硬件扫描码的关键
            public int flags; // 键标志
            public int time; // 指定的时间戳记的这个讯息
            public int dwExtraInfo; // 指定额外信息相关的信息
        }

        //使用此功能，安装了一个钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int SetWindowsHookEx
        (
            int idHook,
            HookProc lpfn,
            IntPtr hInstance,
            int threadId
        );

        //调用此函数卸载钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern bool UnhookWindowsHookEx(int idHook);

        //使用此功能，通过信息钩子继续下一个钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int CallNextHookEx
        (
            int idHook,
            int nCode,
            int wParam,
            IntPtr lParam
        );

        // 取得当前线程编号（线程钩子需要用到）
        [DllImport("kernel32.dll")]
        private static extern int GetCurrentThreadId();

        //使用WINDOWS API函数代替获取当前实例的函数,防止钩子失效
        [DllImport("kernel32.dll")]
        public static extern IntPtr GetModuleHandle(string name);

        //ToAscii职能的转换指定的虚拟键码和键盘状态的相应字符或字符
        [DllImport("user32")]
        public static extern int ToAscii
        (
            int uVirtKey, //[in] 指定虚拟关键代码进行翻译。
            int uScanCode, // [in] 指定的硬件扫描码的关键须翻译成英文。高阶位的这个值设定的关键，如果是（不压）
            byte[] lpbKeyState, // [in] 指针，以256字节数组，包含当前键盘的状态。每个元素（字节）的数组包含状态的一个关键。如果高阶位的字节是一套，关键是下跌（按下）。在低比特，如果设置表明，关键是对切换。在此功能，只有肘位的CAPS LOCK键是相关的。在切换状态的NUM个锁和滚动锁定键被忽略。
            byte[] lpwTransKey, // [out] 指针的缓冲区收到翻译字符或字符。
            int fuState
        ); // [in] Specifies whether a menu is active. This parameter must be 1 if a menu is active, or 0 otherwise.

        //获取按键的状态
        [DllImport("user32")]
        public static extern int GetKeyboardState(byte[] pbKeyState);

        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        private static extern short GetKeyState(int vKey);

        public void Start()
        {
            // 安装键盘钩子
            if (_hKeyboardHook == 0)
            {
                _keyboardHookProcedure = KeyboardHookProc;
                _hKeyboardHook = SetWindowsHookEx(
                    WH_KEYBOARD_LL,
                    _keyboardHookProcedure,
                    GetModuleHandle(System.Diagnostics.Process.GetCurrentProcess().MainModule?.ModuleName),
                    0
                );
                //hKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardHookProcedure, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);
                //************************************
                //键盘线程钩子
                //SetWindowsHookEx( 2,KeyboardHookProcedure, IntPtr.Zero, GetCurrentThreadId());//指定要监听的线程idGetCurrentThreadId(),
                //键盘全局钩子,需要引用空间(using System.Reflection;)
                //SetWindowsHookEx( 13,MouseHookProcedure,Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]),0);
                //
                //关于SetWindowsHookEx (int idHook, HookProc lpfn, IntPtr hInstance, int threadId)函数将钩子加入到钩子链表中，说明一下四个参数：
                //idHook 钩子类型，即确定钩子监听何种消息，上面的代码中设为2，即监听键盘消息并且是线程钩子，如果是全局钩子监听键盘消息应设为13，
                //线程钩子监听鼠标消息设为7，全局钩子监听鼠标消息设为14。lpfn 钩子子程的地址指针。如果dwThreadId参数为0 或是一个由别的进程创建的
                //线程的标识，lpfn必须指向DLL中的钩子子程。 除此以外，lpfn可以指向当前进程的一段钩子子程代码。钩子函数的入口地址，当钩子钩到任何
                //消息后便调用这个函数。hInstance应用程序实例的句柄。标识包含lpfn所指的子程的DLL。如果threadId 标识当前进程创建的一个线程，而且子
                //程代码位于当前进程，hInstance必须为NULL。可以很简单的设定其为本应用程序的实例句柄。threaded 与安装的钩子子程相关联的线程的标识符
                //如果为0，钩子子程与所有的线程关联，即为全局钩子
                //************************************
                //如果SetWindowsHookEx失败
                if (_hKeyboardHook == 0)
                {
                    Stop();
                    throw new Exception("安装键盘钩子失败");
                }
            }
        }

        public void Stop()
        {
            bool retKeyboard = true;
            if (_hKeyboardHook != 0)
            {
                retKeyboard = UnhookWindowsHookEx(_hKeyboardHook);
                _hKeyboardHook = 0;
            }
            try
            {
                if (!(retKeyboard))
                {
                    throw new Exception("卸载钩子失败！");
                }
            }
            catch (Exception)
            {
                // ignored
            }
        }

        ////接收SetWindowsHookEx返回值  
        //private static int _hHookValue = 0;
        private int KeyboardHookProc(int nCode, int wParam, IntPtr lParam)
        {
            // 侦听键盘事件
            if ((nCode >= 0) && (KeyDownEvent != null || KeyUpEvent != null || KeyPressEvent != null))
            {
                KeyboardHookStruct myKeyboardHookStruct = (KeyboardHookStruct)Marshal.PtrToStructure(lParam, typeof(KeyboardHookStruct));
                // raise KeyDown
                if (KeyDownEvent != null && (wParam == WM_KEYDOWN || wParam == WM_SYSKEYDOWN))
                {
                    Keys keyData = (Keys)myKeyboardHookStruct.vkCode;
                    KeyEventArgs e = new KeyEventArgs(keyData);
                    KeyDownEvent(this, e);
                }

                //键盘按下
                if (KeyPressEvent != null && wParam == WM_KEYDOWN)
                {
                    byte[] keyState = new byte[256];
                    GetKeyboardState(keyState);
                    byte[] inBuffer = new byte[2];
                    if (ToAscii(
                            myKeyboardHookStruct.vkCode,
                            myKeyboardHookStruct.scanCode,
                            keyState,
                            inBuffer,
                            myKeyboardHookStruct.flags
                        ) ==
                        1)
                    {
                        KeyPressEventArgs e = new KeyPressEventArgs((char)inBuffer[0]);
                        KeyPressEvent(this, e);
                    }
                }

                // 键盘抬起
                if (KeyUpEvent != null && (wParam == WM_KEYUP || wParam == WM_SYSKEYUP))
                {
                    Keys keyData = (Keys)myKeyboardHookStruct.vkCode;
                    KeyEventArgs e = new KeyEventArgs(keyData);
                    KeyUpEvent(this, e);
                }
            }
            //如果返回1，则结束消息，这个消息到此为止，不再传递。
            //如果返回0或调用CallNextHookEx函数则消息出了这个钩子继续往下传递，也就是传给消息真正的接受者
            return CallNextHookEx(
                _hKeyboardHook,
                nCode,
                wParam,
                lParam
            );
        }

        ~KeyboardHookCommon()
        {
            Stop();
        }
    }
}