/*
CS 349 A1 Skeleton Code - Snake

- - - - - - - - - - - - - - - - - - - - - -

Commands to compile and run:

    g++ -o snake snake.cpp -L/usr/X11R6/lib -lX11 -lstdc++
    ./snake

Note: the -L option and -lstdc++ may not be needed on some machines.
*/

#include <iostream>
#include <list>
#include <cstdlib>
#include <sys/time.h>
#include <math.h>
#include <stdio.h>
#include <unistd.h>

/*
 * Header files for X functions
 */
#include <X11/Xlib.h>
#include <X11/Xutil.h>

using namespace std;

/*
 * Global game state variables
 */
const int Border = 1;
const int BufferSize = 10;
const int FPS = 30;
const int width = 800;
const int height = 600;

/*
 * Information to draw on the window.
 */
typedef struct XInfo
{
	Display	* display;
	int screen;
	Window window;
	GC gc[3];
	int width;		// size of window
	int height;
} Xinfo;


/*
 * Function to put out a message on error exits.
 */
void error(string str)
{
  cerr << str << endl;
  exit(0);
}


/*
 * An abstract class representing displayable things.
 */
class Displayable
{
	public:
		virtual void paint(XInfo & xinfo) = 0;
};

class Snake : public Displayable
{
	public:
		virtual void paint(XInfo & xinfo)
    {
			XFillRectangle(xinfo.display, xinfo.window, xinfo.gc[0], x, y, 25, blockSize);
		}

		void move(XInfo &xinfo)
    {
			x = x + direction;

			if (x < 0 || x > width)
      {
				direction = -direction;
			}

            // ** ADD YOUR LOGIC **
            // Here, you will be performing collision detection between the snake,
            // the fruit, and the obstacles depending on what the snake lands on.
		}

		int getX()
    {
			return x;
		}

		int getY()
    {
			return y;
		}

        /*
         * ** ADD YOUR LOGIC **
         * Use these placeholder methods as guidance for implementing the snake behaviour.
         * You do not have to use these methods, feel free to implement your own.
         */
        void didEatFruit()
        {

        }

        void didHitObstacle()
        {

        }

        void turnLeft()
        {

        }

        void turnRight()
        {

        }

		Snake(int x, int y): x(x), y(y)
    {
			direction = 5;
      blockSize = 10;
		}

	private:
		int x;
		int y;
		int blockSize;
		int direction;
};

class Fruit : public Displayable
{
	public:
		virtual void paint(XInfo & xinfo)
    {
			XFillRectangle(xinfo.display, xinfo.window, xinfo.gc[0], x, y, 10, 10);
    }

        Fruit()
        {
            // ** ADD YOUR LOGIC **
            // generate the x and y value for the fruit
            x = 50;
            y = 50;
        }

        // ** ADD YOUR LOGIC **
        /*
         * The fruit needs to be re-generated at new location every time a snake eats it. See the assignment webpage for more details.
         */

    private:
        int x;
        int y;
};


list<Displayable *> dList;           // list of Displayables
Snake snake(100, 450);
Fruit fruit;


/*
 * Initialize X and create a window
 */
void initX(int argc, char * argv[], XInfo & xInfo)
{
	XSizeHints hints;
	unsigned long white, black;

   /*
	* Display opening uses the DISPLAY	environment variable.
	* It can go wrong if DISPLAY isn't set, or you don't have permission.
	*/
	xInfo.display = XOpenDisplay("");
	if (!xInfo.display)
  {
		error("Can't open display.");
	}

   /*
	* Find out some things about the display you're using.
	*/
	xInfo.screen = DefaultScreen(xInfo.display);

	white = XWhitePixel(xInfo.display, xInfo.screen);
	black = XBlackPixel(xInfo.display, xInfo.screen);

	hints.x = 100;
	hints.y = 100;
	hints.width = 800;
	hints.height = 600;
	hints.flags = PPosition | PSize;

	xInfo.window = XCreateSimpleWindow
  (
		xInfo.display,				// display where window appears
		DefaultRootWindow( xInfo.display ), // window's parent in window tree
		hints.x, hints.y,			// upper left corner location
		hints.width, hints.height,	// size of the window
		Border,						// width of window's border
		black,						// window border colour
		white
  );					// window background colour

	XSetStandardProperties
  (
		xInfo.display,		// display containing the window
		xInfo.window,		// window whose properties are set
		"animation",		// window's title
		"Animate",			// icon's title
		None,				// pixmap for the icon
		argv, argc,			// applications command line args
		&hints
  );			// size hints for the window

	/*
	 * Create Graphics Contexts
	 */
	int i = 0;
	xInfo.gc[i] = XCreateGC(xInfo.display, xInfo.window, 0, 0);
	XSetForeground(xInfo.display, xInfo.gc[i], BlackPixel(xInfo.display, xInfo.screen));
	XSetBackground(xInfo.display, xInfo.gc[i], WhitePixel(xInfo.display, xInfo.screen));
	XSetFillStyle(xInfo.display, xInfo.gc[i], FillSolid);
	XSetLineAttributes(xInfo.display, xInfo.gc[i],
	                     1, LineSolid, CapButt, JoinRound);

	XSelectInput(xInfo.display, xInfo.window,
		ButtonPressMask | KeyPressMask |
		PointerMotionMask |
		EnterWindowMask | LeaveWindowMask |
		StructureNotifyMask);  // for resize events

	/*
	 * Put the window on the screen.
	 */
	XMapRaised( xInfo.display, xInfo.window );
	XFlush(xInfo.display);
}

/*
 * Function to repaint a display list
 */
void repaint( XInfo &xinfo)
{
	list<Displayable *>::const_iterator begin = dList.begin();
	list<Displayable *>::const_iterator end = dList.end();

	XClearWindow( xinfo.display, xinfo.window );

	// get height and width of window (might have changed since last repaint)

	XWindowAttributes windowInfo;
	XGetWindowAttributes(xinfo.display, xinfo.window, &windowInfo);
	unsigned int height = windowInfo.height;
	unsigned int width = windowInfo.width;

	// big black rectangle to clear background

	// draw display list
	while (begin != end)
  {
		Displayable * d = *begin;
		d->paint(xinfo);
		begin++;
	}
	XFlush(xinfo.display);
}

void handleKeyPress(XInfo & xinfo, XEvent & event)
{
	KeySym key;
	char text[BufferSize];

	/*
	 * Exit when 'q' is typed.
	 * This is a simplified approach that does NOT use localization.
	 */
	int i = XLookupString
  (
		(XKeyEvent *)&event, 	// the keyboard event
		text, 					// buffer when text will be written
		BufferSize, 			// size of the text buffer
		&key, 					// workstation-independent key symbol
		NULL
  );
  					// pointer to a composeStatus structure (unused)
	if (i == 1)
  {
		printf("Got key press -- %c\n", text[0]);
		if (text[0] == 'q')
    {
			error("Terminating normally.");
		}
	}
}

void handleAnimation(XInfo & xinfo, int inside)
{
    /*
     * ADD YOUR OWN LOGIC
     * This method handles animation for different objects on the screen and readies the next frame before the screen is re-painted.
     */
	snake.move(xinfo);
}

// get microseconds
unsigned long now()
{
	timeval tv;
	gettimeofday(&tv, NULL);
	return tv.tv_sec * 1000000 + tv.tv_usec;
}

void eventLoop(XInfo & xinfo)
{
	// Add stuff to paint to the display list
	dList.push_front(&snake);
  dList.push_front(&fruit);

	XEvent event;
	unsigned long lastRepaint = 0;
	int inside = 0;

	while(1)
  {
		/*
		 * This is NOT a performant event loop!
		 * It needs help!
		 */

		if (XPending(xinfo.display) > 0)
    {
			XNextEvent(xinfo.display, &event);
			cout << "event.type=" << event.type << "\n";

			switch( event.type )
      {
				case KeyPress:
					handleKeyPress(xinfo, event);
					break;
				case EnterNotify:
					inside = 1;
					break;
				case LeaveNotify:
					inside = 0;
					break;
			}
		}

		usleep(1000000/FPS);
		handleAnimation(xinfo, inside);
		repaint(xinfo);
	}
}


/*
 * Start executing here.
 *	 First initialize window.
 *	 Next loop responding to events.
 *	 Exit forcing window manager to clean up - cheesy, but easy.
 */
int main (int argc, char * argv[])
{
	XInfo xInfo;

	initX(argc, argv, xInfo);
	eventLoop(xInfo);
	XCloseDisplay(xInfo.display);
}