#include <windows.h>
#include <ctime>
#include <cstdlib>
#include <iostream>

using System;

int randInt(int end)
{
    return (int)((rand()*1.0/RAND_MAX)*end);
}

const char g_szClassName[] = "myWindowClass";
const int windowWidth=200;
const int windowHeight=200;
const int drawableWidth=windowWidth-13;
const int drawableHeight=windowHeight-39;

class MyDot
{
    public:
    int x,y;
    float realX,realY,energyY,energyX;
    void initialize()
    {
        srand((unsigned)time(NULL));
        for (int i=0;i<20;i++)
        {
            rand();
        }
        energyX=((rand()*1.0/RAND_MAX)-.5);
        energyY=((rand()*1.0/RAND_MAX)-.5);
        x=randInt(drawableWidth);y=randInt(drawableHeight);
        realX=x;realY=y;
    }
    void draw(HDC hdc)
    {
        SetPixel(hdc,x,y,RGB(157,4,170));
        SetPixel(hdc,x+1,y,RGB(157,4,170));
        SetPixel(hdc,x,y+1,RGB(157,4,170));
        SetPixel(hdc,x+1,y+1,RGB(157,4,170));
    }
    void go()
    {
        realX+=energyX;realY+=energyY;
        x=(int)realX;y=(int)realY;
    }
    void push(float forceX,float forceY)
    {
        energyX+=forceX;
        energyY+=forceY;
    }
};

int a=0;
ArrayList dots=new ArrayList();
RECT myRect;
HBRUSH myBrush;
MyDot dot;
HDC hdcBuffer;
HDC hdc;
HBITMAP hbmBuffer;
HBITMAP hbmOldBuffer;

void paintStuff(HDC hdc)
{
    FillRect(hdcBuffer,&myRect,myBrush);
    dot.draw(hdcBuffer);
    BitBlt(hdc,0,0,windowWidth,windowHeight,hdcBuffer,0,0,SRCCOPY);
}

// Step 4: the Window Procedure
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_CREATE:
        {
            srand((unsigned)time(NULL));
            dot.initialize();
            myBrush=CreateSolidBrush(RGB(255,255,255));
            SetRect(&myRect, 0, 0, windowWidth, windowHeight);
            SetTimer(hwnd,1,17,NULL);
            hdc=GetDC(hwnd);
            hdcBuffer=CreateCompatibleDC(hdc);
            hbmBuffer=CreateCompatibleBitmap(hdc,drawableWidth,drawableHeight);
            SelectObject(hdcBuffer,hbmBuffer);
        }
        break;
        case WM_TIMER:
        {
            a++;
            hdc=GetDC(hwnd);
            paintStuff(hdc);
            ReleaseDC(hwnd, hdc);
            dot.push(0,0.1);
            //Bouncing:
            if (dot.realY>drawableHeight & dot.energyY>0)
            {
                dot.energyY*=-1;
            }
            if (dot.realY<0 & dot.energyY<0)
            {
                dot.energyY*=-1;
            }
            if (dot.realX>drawableWidth & dot.energyX>0)
            {
                dot.energyX*=-1;
            }
            if (dot.realX<0 & dot.energyX<0)
            {
                dot.energyX*=-1;
            }
            dot.go();
        }
        break;
        case WM_PAINT:
        {
            PAINTSTRUCT ps;
            hdc=BeginPaint(hwnd,&ps);
            paintStuff(hdc);
            EndPaint(hwnd,&ps);
        }
        break;
        case WM_LBUTTONDOWN:
        {
            char szFileName[MAX_PATH];
            HINSTANCE hInstance = GetModuleHandle(NULL);

            GetModuleFileName(hInstance, szFileName, MAX_PATH);
            MessageBox(hwnd, szFileName, "This program is:", MB_OK | MB_ICONINFORMATION);
        }
        break;
        case WM_MBUTTONDOWN:
        {
            HDC hdc=GetDC(hwnd);

            TextOut(hdc,a,10,"Hello World",11);

            ReleaseDC(hwnd, hdc);
        }
        break;
        case WM_RBUTTONDOWN:
        {

        }
        break;
        case WM_CLOSE:
            DestroyWindow(hwnd);
        break;
        case WM_DESTROY:
        {
            KillTimer(hwnd,1);
            PostQuitMessage(0);
        }
        break;
        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;

    //Step 1: Registering the Window Class
    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = 0;
    wc.lpfnWndProc   = WndProc;
    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_WINDOW+1);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = g_szClassName;
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

    if(!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    // Step 2: Creating the Window
    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        g_szClassName,
        "The title of my window",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, windowWidth, windowHeight,
        NULL, NULL, hInstance, NULL);

    if(hwnd == NULL)
    {
        MessageBox(NULL, "Window Creation Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    // Step 3: The Message Loop
    while(GetMessage(&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }
    return Msg.wParam;
}