//
// DrawJupiter.java -- display positions of Jupiter's moons.
//	Copyright 1996 by Akkana Peck.
//

// package Akk.Astro;

import java.awt.*;
import java.applet.*;
import java.util.Date;

public class DrawJupiter extends Applet
{
    Jupiter jupiter;

    // Size constants:
    final static int jsize = 10;	// planet's radius in pixels
    final static int moonsize = 4;	// moons' size in pixels
    final static int redSpotWidth = 7;
    final static int redSpotHeight = 5;

     // Copies of the UI components we maintain:
    Canvas drawingArea;
    TextField dateField;
    Choice invertMenu;
    Panel controlPanel;

    Color planetColor;
    Color moonColor;
    Color shadowColor;
    Color lablColor;
    Color bandColor;
    Color spotColor;

    public String getAppletInfo() {
	return "Jovian Moon Locator.\nCopyright 1996 by Akkana Peck";
    }

    public String[][] getParameterInfo() {
	String[][] info = {
	    { "time", "double",
	      "Time of chart (optional, defaults to current)" },
   	};
	return info;
    }

    public void init()
    {
	planetColor = null;

	StarDate now = null;
    	String s = getParameter("time");
	if (s == null)
	    now = new StarDate();
	else
	    now = new StarDate(s);

	//
	// Set some layout info:
	//
	setLayout(new BorderLayout(0, 1));

	//
	// Create the star chart object
	//
	drawingArea = new Canvas();
	add("North", drawingArea);

	dateField = new TextField(now.toString(), 12);
	add("South", dateField);
    }

    public boolean handleEvent(Event event)
    {
	if (event.id == Event.ACTION_EVENT && event.target == dateField )
	{
	    try {
		StarDate newdate = new StarDate(dateField.getText());
		// Might throw IllegalArgumentException if user
		// typed in the wrong format.
	    }
	    catch (IllegalArgumentException e) {
		dateField.setText(new StarDate().toString());
		// should display errmsg ...
	    }
	    finally {
		repaint();
		return true;
	    }
	}

	return super.handleEvent(event);
    }

    public void paint(Graphics g)
    {
    	StarDate date = new StarDate(dateField.getText());
    	if (jupiter == null)
    	    jupiter = new Jupiter(date);
	else
	    jupiter.setDate(date);

        Dimension drawsize = new Dimension(size().width,
                                           size().height -
					     dateField.size().height);
    	int width = drawsize.width;
        int height = drawsize.height;

	// Do some color manipulation:
	if (planetColor == null)
	{
	    drawingArea.setBackground(Color.black);
	    drawingArea.setForeground(Color.white);
	    planetColor = Color.yellow;
	    moonColor = drawingArea.getForeground();
	    shadowColor = Color.black;
	    lablColor = Color.white;
	    bandColor = Color.orange;
	    spotColor = Color.red;
	}

	g.setColor(drawingArea.getBackground());
    	g.fillRect(0, 0, width, height);

    	// draw the planet itself:
    	g.setColor(planetColor);
    	int xcenter = width/2;
    	int ycenter = height/2;
    	g.fillOval(xcenter-jsize, ycenter-jsize, jsize*2, jsize*2);

	XYCoord coord;

	// Draw a couple of fake bands:
	g.setColor(bandColor);
	for (int i=0; i < 4; ++i) {
	    g.drawLine(xcenter-jsize+i, ycenter-i-2,
		       xcenter+jsize-i, ycenter-i-2);
	    g.drawLine(xcenter-jsize+i, ycenter+i+2,
		       xcenter+jsize-i, ycenter+i+2);
	}

	// Find the red spot:
	coord = jupiter.getRedSpotXY();
	if (coord.x != Double.POSITIVE_INFINITY
	    && coord.y != Double.POSITIVE_INFINITY)
	{
	    g.setColor(spotColor);
	    // We only want the spot to draw to the edge of the disk,
	    // so adjust the width if necessary:
	    // (approx) width/2 of the planet (pixels) at the spot's latitude:
	    int j2width = (int)(jsize - Math.abs(coord.y * jsize)/3);
	    int x = xcenter - (int)(coord.x * jsize);
	    int y = ycenter + (int)(coord.y * jsize) - redSpotHeight/2;
	    int spotwidth = redSpotWidth;
	    if (x + redSpotWidth > xcenter + j2width) {
		spotwidth = xcenter + j2width - x;
		x = xcenter + j2width - spotwidth;
	    } else if (x - redSpotWidth/2 < xcenter - j2width) {
		spotwidth = x + redSpotWidth/2 - xcenter + j2width;
		x = xcenter - j2width;
	    }
	    else {
		x -= redSpotWidth/2;
	    }

	    g.fillOval(x, y, spotwidth, redSpotHeight);
	}

    	// draw each of the moons:
	int whichmoon;
	for (whichmoon=0; whichmoon < jupiter.getNumMoons(); ++whichmoon)
	{
	    coord = jupiter.getMoonXY(whichmoon);

	    if ((coord.x != Double.POSITIVE_INFINITY)
		&& (coord.y != Double.POSITIVE_INFINITY))
	    {
		int x = xcenter - (int)(coord.x * jsize) - moonsize/2;
		int y = ycenter + (int)(coord.y * jsize) - moonsize/2;

		g.setColor(drawingArea.getBackground());
		g.drawOval(x-1, y-1, moonsize+2, moonsize+2);
		g.setColor(moonColor);
		g.fillOval(x, y, moonsize, moonsize);

		g.setColor(lablColor);
		g.drawString(jupiter.getMoonLabel(whichmoon),
			     x - moonsize, ycenter - 3*moonsize);
	    }

	    // See if this moon is casting a shadow:
	    coord = jupiter.getMoonShadowXY(whichmoon);
	    if (coord.x != Double.POSITIVE_INFINITY
		&& coord.y != Double.POSITIVE_INFINITY)
	    {
		g.setColor(shadowColor);
		g.fillOval(xcenter - (int)(coord.x * jsize) - moonsize/2,
			   ycenter + (int)(coord.y * jsize) - moonsize/2,
			   moonsize, moonsize);
	    }
	} // end loop over moons
    }
}