import java.awt.*;
import java.awt.event.*;
import java.io.IOException;
import java.net.*;
import java.util.*;


import javax.swing.JPanel;



public class UniPaper extends JPanel
{
	private Set<Point> _inkPoints;
	private UniDraw _draw;

	public UniPaper(UniDraw aUniDraw)
	{
		_draw = aUniDraw;
		_inkPoints = Collections.synchronizedSet(new HashSet<Point>()); 
		// Since regular HashSet isn't threadsafe
		
		PointInputReader pir = new PointInputReader();
		pir.start();
		
		setBackground(Color.WHITE);
		addMouseListener(new L1());
	    addMouseMotionListener(new L2());
	    
	}

	public void paintComponent(Graphics g)
	{
		super.paintComponent(g);
		g.setColor(Color.black);
		
		//Iterators must be synced
		synchronized(_inkPoints)
		{
			Iterator<Point> i = _inkPoints.iterator();
			while(i.hasNext())
			{
				Point p = (Point)i.next();
				g.fillOval(p.x, p.y, 3, 3);
			}
		}
	}
	
	private void addPoint(Point p)
	{
	
		_inkPoints.add(p);
		repaint();
	}
	
	/**
	 * Converts a point into string then into bytes and send it to host and port.
	 * Format of string is: point.x + " " + point.y
	 * @param aPoint The point to send
	 * @param aHost remote host
	 * @param aPort remote port
	 */
	private void sendPoint(Point aPoint)
	{
		String pointAsString = Integer.toString(aPoint.x) + " " + Integer.toString(aPoint.y);
		byte[] pointMsg = pointAsString.getBytes();
		InetAddress iaHost = _draw.getRemoteHost();
		int port = _draw.getRemotePort();
	
		try
		{
			DatagramPacket dp = new DatagramPacket(pointMsg, pointMsg.length, iaHost, port);
			DatagramSocket ds = new DatagramSocket();
			ds.send(dp);
		}
		catch (Exception e)
		{
			System.err.println(e);
		}
		
	}
	
	class PointInputReader extends Thread
	{
		
		@Override
		public void run()
		{
			
			try
			{
				DatagramSocket ds = new DatagramSocket(_draw.getLocalPort());
				byte[] buffer = new byte[65507]; // Max packet size allowed
				DatagramPacket dp = new DatagramPacket(buffer, buffer.length);
				
				while(true)
				{
					try
					{
						ds.receive(dp);
						String message = new String(dp.getData(), 0, dp.getLength());
						String[] xy = message.split(" "); 
						UniPaper.this.addPoint(new Point(Integer.parseInt(xy[0]), Integer.parseInt(xy[1])));
						dp.setLength(65507); // Reset buffer since receive shrinks the buffer.
					}
					catch (IOException e)
					{
						System.err.println(e);
					}
				}
			}
			catch (SocketException e)
			{
				System.err.println(e);
			}
			
		
		}
	}
	
	private void addThenSendPoint(Point p)
	{
		addPoint(p);
		sendPoint(p);
	}
	
	class L1 extends MouseAdapter
	{
		public void mousePressed(MouseEvent e)
		{
			addThenSendPoint(e.getPoint());
		}
	}
	
	class L2 extends MouseMotionAdapter
	{
	    public void mouseDragged(MouseEvent e)
	    {
	    	addThenSendPoint(e.getPoint());
	    }
	}
	
}