import java.awt.*;
import java.util.Observer;
import java.util.Observable;

public class Renderer extends Panel implements Observer
{
	Scrollbar horiz, vert;
	Canvas canvas;
	int canvasWidth, canvasHeight;
	int offsetX=0, offsetY=0;
	int originX=0, originY=0;
	Renderable target=null;
	public Renderer()
	{
		this(null);
	}
	public Renderer(Renderable r)
	{
		createControls();
		setTarget(r);
	}
	public void createControls()
	{
		
		horiz=new Scrollbar(Scrollbar.HORIZONTAL);
		vert=new Scrollbar(Scrollbar.VERTICAL);
		canvas=new Canvas();
		setLayout(new BorderLayout(0,0));
		add("South",horiz);
		add("East",vert);
		add("Center", canvas);
	}
	public void setTarget(Renderable r)
	{
		if (target!=null) target.deleteObserver(this);
		target=r;
		if (target!=null)
		{
			target.addObserver(this);
			setScrollbars();
			repaint();
		}
	}
	public Renderable getTarget()
	{
		return target;
	}
	public void paint(Graphics graphics)
	{					   
		System.out.println("Ran renderable paint");
		//if (target==null) System.out.println("Null target in paint()");
		if (target!=null)
		{
			Graphics g=canvas.getGraphics();
			g.setColor(Color.white);
			g.drawRect(0,0,canvasWidth,canvasHeight);
			g.translate(originX,originY);
			target.render(g);
		}
	}
	public void finalize() throws Throwable
	{
		target.deleteObserver(this);
		super.finalize();
	}
	public synchronized void reshape(int x, int y, int w, int h)
	{
		super.reshape(x,y,w,h);
		Dimension horizDim=horiz.size();
		Dimension vertDim=vert.size();
		canvasWidth=w-vertDim.width;
		canvasHeight=h-horizDim.height;
	}
	public void setScrollbars()
	{
		int width=0, height=0;
		Dimension d = new Dimension(0,0);
		if (target!=null)
		{
			d=target.getDimensions();
			width=d.width-canvasWidth;
			height=d.height-canvasHeight;
			if (offsetX>width)
				offsetX=width;
			if (offsetY>height)
				offsetY=height;
		}
		else
		{
			offsetX=0; offsetY=0;
		}
		width = width < 0 ? 0 : width;
		height = height < 0 ? 0 : height;
		setOrigin(-offsetX, -offsetY);
		horiz.setValues(offsetX, canvasWidth, 0, width);
		horiz.setLineIncrement((int).2*d.width);
		horiz.setPageIncrement((int).5*d.width);
		vert.setValues(offsetY, canvasHeight, 0, height);
		vert.setLineIncrement((int).2*d.height);
		horiz.setPageIncrement((int).5*d.width);
	}
	public boolean handleEvent(Event e)
	{
		if (e.target==horiz)
		{
			switch(e.id)
			{
			case Event.SCROLL_LINE_UP:
			case Event.SCROLL_LINE_DOWN:
			case Event.SCROLL_PAGE_UP:
			case Event.SCROLL_PAGE_DOWN:
			case Event.SCROLL_ABSOLUTE:
				offsetX=((Integer)e.arg).intValue();
			break;
			}
			setOrigin(-offsetX,-offsetY);
			this.repaint();
			return true;
		}
		else if(e.target==vert)
		{
			switch(e.id)
			{
			case Event.SCROLL_LINE_UP:
			case Event.SCROLL_LINE_DOWN:
			case Event.SCROLL_PAGE_UP:
			case Event.SCROLL_PAGE_DOWN:
			case Event.SCROLL_ABSOLUTE:
			offsetY=((Integer)e.arg).intValue();
			break;
			}
			setOrigin(-offsetX,-offsetY);
			this.repaint();
			return true;
		}		
		//canvas.getGraphics().drawString(offsetX+","+offsetY,canvasWidth-50,canvasHeight-20);
		return super.handleEvent(e);
	}

	public void update(Observable o, Object arg)
	{
		if (o==target&&target!=null)
		{
			setScrollbars();
			repaint();
		}
	}
	public void setOrigin(int x, int y)
	{
		originX=x; originY=y;
		repaint();
	}
}