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

class KeyboardHook {
    private const int WH_KEYBOARD_LL = 13;
    private const int WM_KEYDOWN = 0x0104;
    private const int WM_KEYUP = 0x0101;
    private static LowLevelKeyboardProc _proc = HookCallback;
    private static IntPtr _hookID = IntPtr.Zero;

    public static int previousEvent = 0;
    public static event EventHandler<int> KeyDown;
    public static event EventHandler<int> KeyUp;

    public static void Start() {
        _hookID = SetHook(_proc);
    }

    public static void Stop() {
        UnhookWindowsHookEx(_hookID);
    }

    private static IntPtr SetHook(LowLevelKeyboardProc proc) {
        using (Process curProcess = Process.GetCurrentProcess()) using (ProcessModule curModule =
                                                                            curProcess.MainModule) {
            return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0);
        }
    }

    private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);

    private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam) {
        if (nCode >= 0) {
            int vkCode = Marshal.ReadInt32(lParam);
            int pero = (int)wParam * 1000 + vkCode;
            if (pero != previousEvent) {
                if (wParam == (IntPtr)WM_KEYDOWN) {
                    Console.WriteLine($"KeyboardHook: KeyDown event for key {vkCode}");
                    KeyDown?.Invoke(null, vkCode);
                } else if (wParam == (IntPtr)WM_KEYUP) {
                    Console.WriteLine($"KeyboardHook: KeyUp event for key {vkCode}");
                    KeyUp?.Invoke(null, vkCode);
                }
                previousEvent = pero;
            } else {
                Console.WriteLine($"KeyboardHook: Same event filtered out - vkCode: {vkCode}, wParam: {wParam}");
            }
        }
        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }

    [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);
}