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// Begiining game programming, second edition
// Chapter 4
// GameLoop Project

#include <windows.h>
#include <winuser.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define APPTITLE "GameLoop"

// function prototypes
LRESULT CALLBACK WinProc(HWND, UINT, WPARAM, LPARAM);
ATOM MyRegisterClass(HINSTANCE);
BOOL InitInstance(HINSTANCE, int);
void DrawBitmap(HDC, char*, int, int);
void Game_Init();
void Game_Run();
void Game_End();

// Local variables
HWND global_hWnd;
HDC global_hdc;

// the window event callback function
LRESULT CALLBACK WinProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	global_hWnd = hWnd;
	global_hdc = GetDC(hWnd);

	switch(message)
	{
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	}
	return DefWindowProc(hWnd, message, wParam, lParam);
}

// Helper function to set up the window properties
ATOM MyRegisterClass(HINSTANCE hInstance)
{
	// create the window class structure
	WNDCLASSEX wc;
	wc.cbSize = sizeof(WNDCLASSEX);

	// fill the struct with info
	wc.style				= CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc			= (WNDPROC)WinProc;
	wc.cbClsExtra			= 0;
	wc.cbWndExtra			= 0;
	wc.hInstance			= hInstance;
	wc.hIcon				= NULL;
	wc.hCursor				= LoadCursor(NULL, IDC_ARROW);
	wc.hbrBackground		= (HBRUSH)GetStockObject(BLACK_BRUSH);
	wc.lpszMenuName			= NULL;
	wc.lpszClassName		= APPTITLE;
	wc.hIconSm				= NULL;

	// setup the window with the class info
	return RegisterClassEx(&wc);
}


// helper function to create the window and refresh it
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
	HWND hWnd;

	// create a new window
	hWnd = CreateWindow(
		APPTITLE,			// window class
		APPTITLE,			// tittle bar
		WS_OVERLAPPEDWINDOW,// window style
		CW_USEDEFAULT,
		CW_USEDEFAULT,		// window position
		500,				// width of window
		400,				// height of window
		NULL,				// Parent window
		NULL,				// menu
		hInstance,			// application instance
		NULL);				// Window parameters

	// was there an error creating the window?
	if(!hWnd)
		return FALSE;

	// display the window
	ShowWindow(hWnd, nCmdShow);
	UpdateWindow(hWnd);

	return TRUE;
}

// Entry point for a windows program
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
	int done = 0;
	MSG msg;

	// register the class
	MyRegisterClass(hInstance);

	// Initialize the app
	if(!InitInstance(hInstance, nCmdShow))
		return FALSE;

	// Initialize the game
	Game_Init();

	// main message loop
	while(!done)
	{
		if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
		{
			// look for quit message
			if(msg.message ==  WM_QUIT)
				done = 1;

			// decode and pass messages on to WndProc
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}

		// process game loop
		Game_Run();
	}

	// do cleanup
	Game_End();

	return msg.wParam;
}


void Game_Init()
{
	// initialize the game...
	// load bitmaps, meshes, textures, sounds, etc.

	// Initialize the random number generator
	srand(time(NULL));
}


void Game_Run()
{
	// this is called one every frame
	// do not include your own loop here!

	int x = 0, y = 0;
	RECT rect;
	GetClientRect(global_hWnd, &rect);

	if(rect.right > 0)
	{
		x = rand() % (rect.right - rect.left);
		y = rand() % (rect.bottom - rect.top);
		DrawBitmap(global_hdc, "c.bmp", x, y);
	}
}

void Game_End()
{
}


void DrawBitmap(HDC hdcDest, char *filename, int x, int y)
{
	HBITMAP image;
	BITMAP bm;
	HDC hdcMem;

	// load the bitmap image
	image = (HBITMAP)LoadImage(0, "c.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);

	// read the bitmap's properties
	GetObject(image, sizeof(BITMAP), &bm);

	// create a device context for the bitmap
	hdcMem = CreateCompatibleDC(global_hdc);
	SelectObject(hdcMem, image);

	// draw the bitmap to the window (bit block transfer
	BitBlt(
		global_hdc,					// destination device context
		x, y,						// x,y location on destination
		bm.bmWidth, bm.bmHeight,
		hdcMem,						//widht, height of source bitmap
		0, 0,						// sstart x, y, on source bitmap
		SRCCOPY);					// blit method

	// delete the device context and bitmap
	DeleteDC(hdcMem);
	DeleteObject((HBITMAP)image);
}