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

public class LowLevelKeyboardHook
{
    // 1. 定義鉤子類型和消息類型常量
    private const int WH_KEYBOARD_LL = 13; // 低級鍵盤鉤子
    private const int WM_KEYDOWN = 0x0100; // 按鍵按下
    private const int WM_KEYUP = 0x0101;   // 按鍵釋放

    // 2. 定義鉤子回調函數(shù)的委托
    public delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);

    // 3. 導入所需的Windows API函數(shù)
    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool UnhookWindowsHookEx(IntPtr hhk);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr GetModuleHandle(string lpModuleName);

    // 4. 定義鍵盤鉤子結構體，用于解析消息參數(shù)
    [StructLayout(LayoutKind.Sequential)]
    public struct KBDLLHOOKSTRUCT
    {
        public int vkCode;      // 虛擬鍵碼
        public int scanCode;    // 掃描碼
        public int flags;
        public int time;
        public IntPtr dwExtraInfo;
    }
}

public class LowLevelKeyboardHook
{
    // ... (上述聲明部分)

    private IntPtr _hookID = IntPtr.Zero;
    private LowLevelKeyboardProc _hookProc;

    // 定義事件，便于外部訂閱按鍵操作
    public event EventHandler<KeyEventArgs> KeyDown;
    public event EventHandler<KeyEventArgs> KeyUp;

    public LowLevelKeyboardHook()
    {
        _hookProc = HookCallback; // 初始化回調函數(shù)
    }

    /// <summary>
    /// 安裝并啟動鍵盤鉤子
    /// </summary>
    public void Start()
    {
        if (_hookID == IntPtr.Zero)
        {
            // 關鍵：獲取當前進程的模塊句柄
            using (Process curProcess = Process.GetCurrentProcess())
            using (ProcessModule curModule = curProcess.MainModule)
            {
                _hookID = SetWindowsHookEx(WH_KEYBOARD_LL, _hookProc,
                    GetModuleHandle(curModule.ModuleName), 0);
            }
            // 錯誤處理
            if (_hookID == IntPtr.Zero)
            {
                throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
            }
        }
    }

    /// <summary>
    /// 卸載鉤子
    /// </summary>
    public void Stop()
    {
        if (_hookID != IntPtr.Zero)
        {
            bool success = UnhookWindowsHookEx(_hookID);
            _hookID = IntPtr.Zero;
            if (!success)
            {
                throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
            }
        }
    }

    /// <summary>
    /// 鉤子回調函數(shù)，這是核心處理邏輯
    /// </summary>
    private IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        // 如果 nCode >= 0，說明消息需要處理
        if (nCode >= 0)
        {
            // 從 lParam 中提取按鍵信息
            KBDLLHOOKSTRUCT hookStruct = Marshal.PtrToStructure<KBDLLHOOKSTRUCT>(lParam);
            Keys key = (Keys)hookStruct.vkCode;

            // 根據(jù)消息類型觸發(fā)不同事件
            if (wParam == (IntPtr)WM_KEYDOWN)
            {
                KeyDown?.Invoke(this, new KeyEventArgs(key));
            }
            else if (wParam == (IntPtr)WM_KEYUP)
            {
                KeyUp?.Invoke(this, new KeyEventArgs(key));
            }

            // 示例：攔截A鍵，使其無效
            // if (key == Keys.A)
            // {
            //     return (IntPtr)1; // 返回非零值表示消息已被處理，不再傳遞
            // }
        }

        // 將消息傳遞給鉤子鏈中的下一個鉤子
        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }
}

public partial class MainForm : Form
{
    private LowLevelKeyboardHook _keyboardHook;

    public MainForm()
    {
        InitializeComponent();
        _keyboardHook = new LowLevelKeyboardHook();

        // 訂閱事件
        _keyboardHook.KeyDown += OnGlobalKeyDown;
        _keyboardHook.KeyUp += OnGlobalKeyUp;

        // 安裝鉤子
        _keyboardHook.Start();
    }

    private void OnGlobalKeyDown(object sender, KeyEventArgs e)
    {
        // 實時顯示按下的鍵
        Console.WriteLine($"鍵按下: {e.KeyCode}");

        // 示例：檢測Ctrl+Shift+A全局快捷鍵
        if (e.KeyCode == Keys.A && Control.ModifierKeys.HasFlag(Keys.Control) && Control.ModifierKeys.HasFlag(Keys.Shift))
        {
            MessageBox.Show("全局快捷鍵 Ctrl+Shift+A 被觸發(fā)！");
            e.Handled = true; // 標記為已處理
            // 如果需要攔截此組合鍵，使其不影響其他程序，需在上述回調函數(shù)中返回1
        }
    }

    private void OnGlobalKeyUp(object sender, KeyEventArgs e)
    {
        // 處理按鍵釋放
    }

    protected override void OnFormClosed(FormClosedEventArgs e)
    {
        base.OnFormClosed(e);
        // 窗體關閉時務必卸載鉤子，釋放資源
        _keyboardHook.Stop();
    }
}