// -*-Java-*-

import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Font;
import java.awt.Color;
import java.awt.Shape;
import com.koniaris.astronomy.Moon;
import com.koniaris.astronomy.JulianDay;

// Look at the source of the web page "http://www.koniaris.com/lunar" to see how this applet is called

public class ShowMoon extends Applet implements Runnable {

    // ----------------------------------------------------------------------

    // local variables
    private int ip; // the illuminated percentage
    private boolean waning; // is the moon getting darker?
    private Thread t;
    private boolean exit = false;
    private boolean pause = false;
    private Font myFont;
    private Color black; // the background
    private Color yellow; // the foreground
    private Color white; // the percentage
    private int sleep; // how many ms we sleep

    // ----------------------------------------------------------------------

    private int parameterAsInt(String p) {
	return Integer.parseInt(getParameter(p));
    }

    // ----------------------------------------------------------------------


    private Color getColor(String rgb) {
	return new Color(Integer.parseInt(getParameter(rgb), 16));
    }

    // ----------------------------------------------------------------------

    public void init() {
	try {
	    update_moon();
	    // set the sleep time
	    sleep = parameterAsInt("sleep");
	    if (sleep < 1) sleep = 1;
	    sleep *= 1000; // to put it into units of ms, what is required
	    // launch the thread, and it will block
	    t = new Thread(this);
	    pause = true;
	    t.start(); // the thread will block until a notify()
	    // get the font
	    myFont = new Font(getParameter("font"), Font.BOLD, parameterAsInt("fontSize"));
	    // get the colors
	    black = getColor("black");
	    yellow = getColor("yellow");
	    white = getColor("white");
	} catch(Exception e) {
	    // oops, something went wrong....
	    ip = -1;
	}
    }

    // ----------------------------------------------------------------------

    public void start() {
	pause = false;
	synchronized(this) {
	    this.notify(); // let the thread resume
	}
    }

    // ----------------------------------------------------------------------

    public void stop() {
	pause = true;
    }

    // ----------------------------------------------------------------------

    public void destroy() {
	exit = true;
	pause = false;
	synchronized(this) {
	    this.notify(); // wake it up so it can decide to return in case it is sleeping
	}
	t = null; // cut the pointer to the thread loose for easier GC
    }

    // ----------------------------------------------------------------------

    private void update_moon() throws Exception {
	// this sets the illuminated percentage of the moon
	JulianDay j = new JulianDay();
	Moon m = new Moon(j);
	ip = m.illuminatedPercentage();
	waning = m.isWaning();
    }

    // ----------------------------------------------------------------------

    // ----|---- waxing 0%
    // ----|---* 
    // ----|--** black circle, clip R, yellow circle, black oval
    // ----|-***
    // ----|**** 50%
    // ---*|****
    // --**|**** yellow circle, clip L, black circle, yellow oval
    // -***|****
    // ****|**** waning 100%
    // ****|***-
    // ****|**-- yellow circle, clip R, black circle, yellow oval
    // ****|*--- 
    // ****|---- 50%
    // ***-|----
    // **--|---- black circle, clip L, yellow circle, black oval
    // *---|----

    public void paint(Graphics g) {
	// I was too lazy to double-buffer here, as it's unnecessary

	// It's an interesting question as to if I really have to grab
	// a lock here....

	// And do I keep on getting the same g?  It would be extremely
	// convenient to know that, as I could transform the
	// coordinate system, only install my font one time, etc.!

	synchronized(g) { // ???

	    // get the sizes
	    int w = getSize().width;
	    int h = getSize().height; 

	    // set the center to something reasonable
	    int x = w/2;
	    int y = h/2;

	    // get the radius of the circle
	    int radius = (int) (0.40 * ((w < h) ? w : h));
	    int diameter = 2 * radius;

	    // determine the majority and minority colors
	    Color majority, minority;
	    boolean clipRight;
	    if (ip > 50) {
		majority = yellow;
		minority = black;
		clipRight = waning;
	    } else {
		majority = black;
		minority = yellow;
		clipRight = ! waning;
	    }
	    
	    // draw the big background
	    g.setColor(majority);
	    g.fillOval(x - radius, y - radius, // the starting point
		       diameter, diameter); // the sides of the bounding box

	    // save the clipping path
	    Shape clip = g.getClip();

	    // clip....
	    if (clipRight) {
		g.clipRect(x, y - radius, radius, diameter);
	    } else {
		// Sun did the wrong thing with a negative width, IMHO
		g.clipRect(x - radius, y - radius, radius, diameter);
	    }

	    // draw the semi-circle
	    g.setColor(minority);
	    g.fillOval(x - radius, y - radius, // the starting point
		       diameter, diameter); // the sides of the bounding box

	    // draw the majority
	    g.setColor(majority);
	    int xxx = (int) Math.abs((ip - 50) * radius / 50.0); // the width of the oval (0 when 50%/50%)
	    g.fillOval(x - xxx, y - radius, 2 * xxx, diameter);

	    // restore the clipping path
	    g.setClip(clip);

	    // install my font
	    g.setFont(myFont);

	    // draw the percentage in the middle
	    g.setColor(white);
	    g.drawString(ip + "%" + (waning ? "-" : "+"), x, y);
	}
    }

    // ----------------------------------------------------------------------

    public void run() {
	try {
	    try {
		while (! exit) {
		    while (pause)
		    synchronized(this) {
			this.wait(); // wait until the start() method wakes us up....
		    }
		    // has the moon changed?
		    int old_ip = ip; // get the old illuminated portion
		    update_moon(); // update the phase of the moon
		    if (old_ip != ip) {
			// COOL, IT CHANGED!  :)
			repaint();
		    }
		    synchronized(this) {
			this.wait(sleep);
		    }
		}
	    } catch(InterruptedException e) {
		// we'll just fall thru....
	    }
	} catch(Exception e) {
	    // alas, a bug on my part?
	}
    }

    // ----------------------------------------------------------------------
}