include <windows.h>
#include <time.h>

//V-6

LPCSTR registration_error_message = "Couldn't initialize class!";
LPCSTR registration_error_title = "Error: initializing";
LPCSTR creating_window_error_title = "Error: creating";
LPCSTR creating_window_error_message = "Couldn't create window!";

LPCSTR button_show_text = "Show";
LPCSTR button_clear_text = "Clear";
LPCSTR button_about_text = "About";

LPCSTR main_window_name = "Hello App";
LPCSTR main_window_class = "hello_class";

LPCSTR about_text = "Sergey Rakhmanov (IU3-21B)";

LRESULT CALLBACK window_callback(HWND, UINT, WPARAM, LPARAM);
HINSTANCE hInst;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) {
   HWND main_window;
   MSG msg;
   WNDCLASSEX wc;

   wc.cbSize        = sizeof(wc);
   wc.style         = CS_HREDRAW | CS_VREDRAW;
   wc.lpfnWndProc   = window_callback;
   wc.lpszMenuName  = NULL;
   wc.lpszClassName = main_window_class;
   wc.cbWndExtra    = 0;
   wc.cbClsExtra    = 0;
   wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
   wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);
   wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
   wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
   wc.hInstance     = hInstance;

   if(!RegisterClassEx(&wc)){
       MessageBox(NULL, registration_error_message, registration_error_title, MB_OK);
       return NULL;
   }

   main_window = CreateWindow(main_window_class,
                              main_window_name,
                              WS_OVERLAPPEDWINDOW,
                              CW_USEDEFAULT,
                              CW_USEDEFAULT,
                              CW_USEDEFAULT,
                              CW_USEDEFAULT,
                              NULL,
                              NULL,
                              hInstance,
                              NULL);

   if(!main_window){
       MessageBox(NULL, creating_window_error_message, creating_window_error_title, MB_OK);
       return NULL;
   }

   ShowWindow(main_window, iCmdShow);
   UpdateWindow(main_window);

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

#define BTN_WIDTH 150
#define BTN_HEIGHT 20
LRESULT CALLBACK window_callback(HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam){
   HDC hdc;
   PAINTSTRUCT ps;
   RECT rect;
   HWND button_show, button_clear, button_author;
   int loword;
   static int choise = 0;
   static HPEN hpen;
   static HBRUSH hbrush;

   switch (iMsg) {
       case WM_CREATE :
           button_show = CreateWindow ("button", button_show_text,
                                       WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
                                       100, 50, BTN_WIDTH, BTN_HEIGHT,
                                       hwnd, (HMENU) 1, hInst, NULL);

           button_clear = CreateWindow ("button", button_clear_text,
                                       WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
                                       100, 100, BTN_WIDTH, BTN_HEIGHT,
                                       hwnd, (HMENU) 2, hInst, NULL);

           button_author = CreateWindow ("button", button_about_text,
                                       WS_CHILD | WS_VISIBLE |BS_PUSHBUTTON,
                                       100, 250, BTN_WIDTH, BTN_HEIGHT,
                                       hwnd, (HMENU) 3, hInst, NULL);
           return 0;

       case WM_COMMAND :
           hpen = CreatePen(PS_SOLID, 10,RGB(204, 51, 0));
           hbrush = CreateSolidBrush(RGB(204, 51, 0));
           loword=LOWORD(wParam);

           switch(loword){
               case 1:
                   choise = 1;
                   break;
               case 2:
                   choise = 2;
                   break;
               case 3:
                   choise = 3;
                   break;
               default:
                   break;
           }

           InvalidateRect(hwnd, NULL, TRUE);
           return 0;

       case WM_PAINT:
           hdc = BeginPaint(hwnd, &ps);

           GetClientRect(hwnd, &rect);
           SelectObject(hdc, hbrush);
           SelectObject(hdc, hpen);

           switch(choise){
               case 1:
                   Rectangle(hdc, 600, 100, 624, 300);

                   hbrush = CreateSolidBrush(RGB(0, 255, 0));
                   hpen = CreatePen(PS_SOLID, 10,RGB(0, 255, 0));
                   SelectObject(hdc, hbrush);
                   SelectObject(hdc, hpen);

                   Ellipse(hdc, 525, 50, 698, 200);
                   break;
               case 2:
                   break;
               case 3:
                   TextOut(hdc, 500, 100, about_text, strlen(about_text));
                   break;
           }

           EndPaint(hwnd, &ps);
           return 0;

       case WM_DESTROY :
           PostQuitMessage(0);
           return 0;
   }

   return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
}