#include <windows.h>
#include <string>

const WCHAR g_szClassName[] = L"TestProgram";

HINSTANCE g_hInstance;
HWND g_hwnd;
INT g_nCount;

DWORD g_dwStyle = WS_CLIPCHILDREN | WS_CLIPSIBLINGS | WS_DLGFRAME | WS_POPUP;
DWORD g_dwExStyle = WS_EX_TOPMOST | WS_EX_WINDOWEDGE;

std::wstring g_str;

LRESULT CALLBACK
WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    RECT rc;
    HWND hChild;

    switch(uMsg)
    {
    case WM_CREATE:
        if (g_nCount < 5)
        {
            g_nCount++;
            GetWindowRect(hwnd, &rc);
            hChild = CreateWindowExW(
                g_dwExStyle, g_szClassName, g_szClassName, g_dwStyle,
                rc.left + 10, rc.top + 10, 100, 100,
                hwnd, NULL, g_hInstance, NULL);
            ShowWindow(hChild, SW_SHOW);
            UpdateWindow(hChild);
        }
        else
        {
            SetTimer(hwnd, 999, 400, NULL);
        }
        break;

    case WM_TIMER:
        if (wParam == 999)
        {
            KillTimer(hwnd, 999);
            HWND hParent = GetParent(hwnd);
            if (hParent)
            {
                SetActiveWindow(hParent);
                DestroyWindow(hwnd);
                if (GetActiveWindow() == hParent)
                {
                    g_str += L"success\n";
                }
                else
                {
                    g_str += L"failure\n";
                }
                SetTimer(hParent, 999, 400, NULL);
            }
            else
            {
                DestroyWindow(hwnd);
                PostQuitMessage(0);
            }
        }
        break;

    default:
        return DefWindowProc(hwnd, uMsg, wParam, lParam);
    }
    return 0;
}

INT WINAPI
WinMain(HINSTANCE hInstance,
        HINSTANCE hPrevInstance,
        LPSTR pszCmdLine,
        INT nCmdShow)
{
    g_hInstance = hInstance;

    WNDCLASSW wc;
    wc.style = 0;
    wc.lpfnWndProc = WindowProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_3DFACE + 1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = g_szClassName;
    if (!RegisterClassW(&wc))
    {
        MessageBoxW(NULL, L"Error: register class", NULL, MB_ICONERROR);
        return 1;
    }

    g_nCount = 0;

    g_hwnd = CreateWindowExW(g_dwExStyle, g_szClassName, g_szClassName,
        g_dwStyle, CW_USEDEFAULT, CW_USEDEFAULT, 100, 100,
        NULL, NULL, hInstance, NULL);
    if (g_hwnd == NULL)
    {
        MessageBoxW(NULL, L"Error: create window", NULL, MB_ICONERROR);
        return 2;
    }

    ShowWindow(g_hwnd, SW_SHOW);
    UpdateWindow(g_hwnd);

    MSG msg;
    while(GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    MessageBoxW(NULL, g_str.c_str(), L"result", MB_ICONINFORMATION);

    return (INT)msg.wParam;
}