#include <windows.h>
LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM WParam, LPARAM lParam);
LRESULT CALLBACK ChildProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
HINSTANCE g_hInst;
HWND hWndMain;
RECT Mainrt;


int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR nCmdLine, int nCmdShow) {
    LPCTSTR lpszClassName = TEXT("클래스");

    HWND hWnd;
    MSG msg;
    g_hInst = hInstance;
    WNDCLASSEX wc;

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    wc.lpfnWndProc = WndProc;
    wc.lpszClassName = lpszClassName;
    wc.lpszMenuName = NULL;
    wc.hInstance = hInstance;
    RegisterClassEx(&wc);

    wc.hbrBackground = (HBRUSH)(COLOR_BTNFACE + 1);
    wc.style = CS_NOCLOSE | CS_VREDRAW;
    wc.lpszClassName = TEXT("부모 윈도우");
    wc.lpfnWndProc = ChildProc;
    RegisterClassEx(&wc);

    hWnd = CreateWindow(
        lpszClassName,
        TEXT("Adhere"),
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        NULL,
        NULL,
        hInstance,
        0);

    if (!hWnd) {
        return FALSE;
    }

    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

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

    return msg.wParam;
}


LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    HDC hdc;
    PAINTSTRUCT ps;
    HWND hWndChild;

    switch (uMsg) {
    case WM_CREATE:
        hWndMain = hWnd;
        hWndChild = CreateWindow(
            TEXT("부모 윈도우"),
            TEXT("팔레트"),
            WS_POPUP | WS_CAPTION | WS_THICKFRAME | WS_SYSMENU,
            200, 250, 200, 200,
            hWndMain,
            NULL,
            g_hInst,
            NULL);
        ShowWindow(hWndChild, SW_SHOW);
        return 0;
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);
        EndPaint(hWnd, &ps);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }

    return DefWindowProc(hWnd, uMsg, wParam, lParam);
}


LRESULT CALLBACK ChildProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    HDC hdc;
    PAINTSTRUCT ps;
    LPWINDOWPOS wp;
    int height;
    int t;

    switch (uMsg) {
    case WM_CREATE:
        return 0;
    case WM_WINDOWPOSCHANGING:
        GetWindowRect(hWndMain, &Mainrt);
        height = Mainrt.bottom - Mainrt.top;
        wp = (LPWINDOWPOS)lParam;
        wp->cx = 200;
        wp->cy = min(max(wp->cy, height / 4), height);
        t = wp->x;

        if (abs(Mainrt.left - t) < 30)
            t = Mainrt.left + 10;
        if (abs(Mainrt.right - (t + wp->cx)) < 30)
            t = (Mainrt.right - wp->cx) - 10;
        wp->x = t;
        return 0;
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);
        EndPaint(hWnd, &ps);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }

    return DefWindowProc(hWnd, uMsg, wParam, lParam);
}