#include <windows.h>
#include "hooklib\hooklib.h"

/* local prototypes */
DWORD AlertThreadProc(LPVOID);
LRESULT CALLBACK WindowProc(HWND, UINT, WPARAM, LPARAM);

/* application entry-point */
int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCmdLine, int nCmdShow )
{
	WNDCLASSEX wc;
	HWND hwnd;
	MSG msg;
	int ret;

	/* register our window class */
	RtlZeroMemory(&wc, sizeof(WNDCLASSEX));
	wc.cbSize = sizeof(WNDCLASSEX);
	wc.lpfnWndProc = WindowProc;
	wc.hInstance = hInstance;
	wc.lpszClassName = L"LifeGuardWindow";
	RegisterClassEx(&wc);

	/* create the message window */
	hwnd = CreateWindowEx(0, L"LifeGuardWindow", NULL, 0, 0, 0, 0, 0, 0, 0, hInstance, 0);
	if( !IsWindow(hwnd) ) {
		MessageBox(0, L"Failed to create message window.", L"LifeGuard", MB_ICONERROR);
		return GetLastError();
	}

	/* notify this process first about a pending shut down */
	SetProcessShutdownParameters(0x4FF, 0);

	/* register the message hook */
	ret = RegisterHook(hwnd);
	if( ret != ERROR_SUCCESS ) {
		ret = GetLastError();
		DestroyWindow(hwnd);
		
		MessageBox(0, L"Failed to register message hook.", L"LifeGuard", MB_ICONERROR);
		return ret;
	}

	/* message pump */
	while( GetMessage(&msg, hwnd, 0, 0) > 0 ) {
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return 0;
}

/* thread procedure for shut down alerts */
DWORD AlertThreadProc( LPVOID lpv )
{
	MessageBox(0, L"A system shut down request was detected.", L"LifeGuard", MB_ICONWARNING);
	return 0;
}

/* window message procedure */
LRESULT CALLBACK WindowProc( HWND hWnd, UINT uiMessage, WPARAM wParam, LPARAM lParam )
{
	if( uiMessage == WM_USER ) {
		/* alert the user that a shut down message was blocked */
		CreateThread(
			NULL, 
			0, 
			(LPTHREAD_START_ROUTINE)AlertThreadProc, 
			NULL, 
			STANDARD_RIGHTS_REQUIRED, 
			NULL);
		return 0;
	} else
		return DefWindowProc(hWnd, uiMessage, wParam, lParam);
}