Snake V0.00001

#include <Windows.h>

#define TIMER_TIME 250
#define TIMER_ID 100
#define SPEED 50

HWND hwnd;

enum Vector { Left, Right, Up, Down };

struct Snake {
    int PosX, PosY;
    int Width, Height;
    COLORREF BorderColor, FillColor;
    Vector vector, PrevVector;
};

Snake snake;

void PrintSnake(Snake &snak) {
    PAINTSTRUCT PS;
    HDC hdc = BeginPaint(hwnd, &PS);

    HBRUSH Brush = CreateSolidBrush(snak.FillColor);
    HPEN Pen = CreatePen(PS_SOLID, 2, snak.BorderColor);

    HBRUSH OldBrush = (HBRUSH)SelectObject(hdc, Brush);
    HPEN OldPen = (HPEN)SelectObject(hdc, Pen);

    Rectangle(hdc, snak.PosX, snak.PosY, snak.PosX + snak.Width, snak.PosY + snak.Height);

    SelectObject(hdc, OldBrush);
    SelectObject(hdc, OldPen);

    DeleteObject(Brush);
    DeleteObject(Pen);

    EndPaint(hwnd, &PS);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    switch (msg) {
    case WM_CREATE:break;
    case WM_COMMAND:break;
    case WM_TIMER: {
        RECT WndRect;
        GetClientRect(hwnd, &WndRect);

        // for 255 -> 0
        switch (snake.vector) {
        case Up:

            snake.PosY -= SPEED;
            if (snake.PosY < WndRect.top) snake.PosY = WndRect.bottom - snake.Height;

            break;
        case Down:

            snake.PosY += SPEED;
            if (snake.PosY + snake.Height > WndRect.bottom) snake.PosY = 0;

            break;
        case Left:

            snake.PosX -= SPEED;
            if (snake.PosX < WndRect.left) snake.PosX = WndRect.right - snake.Width;

            break;
        case Right:

            snake.PosX += SPEED;

            if (snake.PosX + snake.Width > WndRect.right) snake.PosX = 0;

            break;
        }

        InvalidateRect(hwnd, &WndRect, 1);
        PrintSnake(snake);//[255]

    }break;
    case WM_PAINT: {
        PrintSnake(snake);//[255]

    }break;

    case WM_KEYDOWN: {

        switch ((int)wParam) {
        case VK_UP:
            snake.PrevVector = snake.vector;
            if (snake.PrevVector != Down) {
                snake.vector = Up;
            }
            break;

        case VK_DOWN:
            snake.PrevVector = snake.vector;
            if (snake.PrevVector != Down) {
                snake.vector = Down;
            }
            break;

        case VK_RIGHT:
            snake.vector = Right;
            break;

        case VK_LEFT:
            snake.vector = Left;
            break;
        }
    }break;

    case WM_CLOSE:  DestroyWindow(hwnd);    break;
    case WM_DESTROY:PostQuitMessage(0);     break;
    default:    return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR ilCmdLine, int nCmdShow) {
    WNDCLASSEX window;
    MSG msg;
    TCHAR Class_Name[] = TEXT("OKNO_TEST"), Title[] = TEXT("Tytul");

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

    if (!RegisterClassEx(&window)) {
        MessageBox(NULL, TEXT("Błąd rejestracji okna"), TEXT("Błąd"), MB_ICONEXCLAMATION);
        return 0;
    }

    hwnd = CreateWindowEx(WS_EX_WINDOWEDGE, Class_Name, Title, WS_OVERLAPPEDWINDOW | WS_VISIBLE, CW_USEDEFAULT, CW_USEDEFAULT, 800, 600, NULL, NULL, hInstance, NULL);

    if (hwnd == NULL) {
        MessageBox(NULL, TEXT("Błąd tworzenia okna"), TEXT("Błąd"), MB_ICONEXCLAMATION);
        return 0;
    }

    snake.BorderColor = RGB(0, 0, 0);
    snake.FillColor = RGB(255, 0, 255);
    snake.Width = 50;
    snake.Height = 50;
    snake.PosX = 100;
    snake.PosY = 100;
    snake.vector = Down;

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);
    SetTimer(hwnd, TIMER_ID, TIMER_TIME, NULL);

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

    if (!UnregisterClass(Class_Name, hInstance)) {
        MessageBox(NULL, TEXT("Błąd niszczenia okna"), TEXT("Błąd"), MB_ICONEXCLAMATION);
        return 0;
    }
    return msg.wParam;
}