import java.awt.*;
import Planet;
import Rocket;

public class GraphPanel extends Panel
{
	public double minY;
	public double maxY;
	public double minX;
	public double maxX;
	public double xScale;
	
	protected double values[];		// array of values to plot
	protected Rectangle graphRect;

	public void init() {
		graphRect = new Rectangle();
		graphRect.resize(0,0);
		xScale = 1;
	}
	
	public void resize(Dimension d) { resize(d.width, d.height); }
	
	public void resize(int width, int height) {
		// here, we'll just set graphRect's width to 0
		// to signify that we need to recalculate it later!
		graphRect.resize(0,0);
	}	


	protected double calcBoundUp( double x ) { return calcBound(x,1); }
	protected double calcBoundDown( double x) { return calcBound(x,-1); }
	protected double calcBound( double x, int sign ) {
		// this function takes a number x, and calculates a nice "round" number
		// greater than x for use as an upper bound on the Y-axis.
		if (x == 0) return 0;
		double round5 = Math.pow(5, (int)(Math.log(x) / Math.log(5) - 1) );
		return ( (int)(x / round5) + sign) * round5;
	}

	public void setData( double data[] ) {
		values = data;
		minX = 0;
		maxX = data.length - 1;
		minY = data[0];
		maxY = data[0];
		for (int i=0; i<maxX; i++) {
			if (data[i] < minY) minY = data[i];
			if (data[i] > maxY) maxY = data[i];
		}
		// now we have max and min, round them to nice even numbers
		minY = calcBoundDown( minY );
		maxY = calcBoundUp( maxY );
	}
	
	protected void setGraphRect() {
		graphRect = getGraphics().getClipRect();
		graphRect.x += 40;
		graphRect.y += 4;
		graphRect.width -= 44;
		graphRect.height -= 24;
	}
	
	protected int valToScreenX(double x) {
		return (int)(graphRect.x + (x-minX)/(maxX-minX) * graphRect.width);
	}
	
	protected int valToScreenY(double y) {
		return (int)(graphRect.y + graphRect.height -
				 (y-minY)/(maxY-minY) * graphRect.height);
	}
	
	public void paint( Graphics g ) {
		if (graphRect.width < 1) setGraphRect();
		g.setColor( Color.black );
		g.drawRect( graphRect.x-1, graphRect.y-1, graphRect.width+2, graphRect.height+2 );
		g.setColor( Color.white );
		g.fillRect( graphRect.x, graphRect.y, graphRect.width, graphRect.height );

		g.setColor( Color.red );
		for (int i=0; i<values.length-1; i++) {
			g.drawLine( valToScreenX(i), valToScreenY(values[i]),
						valToScreenX(i+1), valToScreenY(values[i+1]) );
		}
		
		g.setColor( Color.black );
		g.drawString( ""+maxY, 2, graphRect.y + 12 );
		g.drawString( ""+minY, 2, graphRect.y + graphRect.height );
		g.drawString( ""+minX, graphRect.x, graphRect.y + graphRect.height + 16 );
		g.drawString( ""+maxX*xScale, graphRect.x + graphRect.width - 20, 
						graphRect.y + graphRect.height + 16 );
			
	}
}