#include "windows.h"
#include "stdio.h"

#define _WIN32_WINNT 0400

DWORD g_main_tid = 0;
HHOOK g_kb_hook = 0;

bool CALLBACK con_handler (DWORD)
{
    PostThreadMessage (g_main_tid, WM_QUIT, 0, 0);
    return TRUE;
};

LRESULT CALLBACK kb_proc (int code, WPARAM w, LPARAM l)
{
    PKBDLLHOOKSTRUCT p = (PKBDLLHOOKSTRUCT)l;
    const char *info = NULL;
    if (w == WM_KEYDOWN)
        info = "key dn";
    else if (w == WM_KEYUP)
        info = "key up";
    else if (w == WM_SYSKEYDOWN)
        info = "sys key dn";
    else if (w == WM_SYSKEYUP)
        info = "sys key up";
    printf ("%s - vkCode [%04x], scanCode [%04x]\n",
        info, p->vkCode, p->scanCode);
    // always call next hook
    return CallNextHookEx (g_kb_hook, code, w, l);
};

int main (void)
{
    g_main_tid = GetCurrentThreadId ();
    SetConsoleCtrlHandler (&con_handler, TRUE);
    g_kb_hook = SetWindowsHookEx (
        WH_KEYBOARD_LL,
        &kb_proc,
        GetModuleHandle (NULL), //　不能为NULL，否则失败
        0);
    if (g_kb_hook == NULL)
    {
        fprintf (stderr,
            "SetWindowsHookEx failed with error %d\n",
            ::GetLastError ());
        return 0;
    };
    // 消息循环是必须的，想知道原因可以查msdn
    MSG msg;
    while (GetMessage (&msg, NULL, 0, 0))
    {
        TranslateMessage (&msg);
        DispatchMessage (&msg);
    };
    UnhookWindowsHookEx (g_kb_hook);
    return 0;
};