/*
* Copyright (c) 1998 Bill Venners. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for EVALUATION purposes only
* is hereby granted provided that this copyright notice
* appears in all copies. "Evaluation purposes" are any uses which
* do not constitute the sale, sharing, or redistribution of this
* software with or to any other persons in any medium.
*
* BILL VENNERS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT
* THE SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. ARTIMA SOFTWARE COMPANY
* SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
* USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/

/*
* TrafficLightApplet.java
*
* This file contains all the code for the traffic light state machine
* applet, shown as Figure 1 in the JavaWorld Design Techniques
* article titled,"Designing Object Initialization".
*
* Bill Venners, January 1998
*/

import java.applet.*;
import java.awt.*;

class TrafficLight {

	public static final int RED = 0;
	public static final int YELLOW = 1;
	public static final int GREEN = 2;

	private int currentColor = RED;

	public int change() {

		switch (currentColor) {

		case RED:
			currentColor = GREEN;
			break;

		case YELLOW:
			currentColor = RED;
			break;

		case GREEN:
			currentColor = YELLOW;
			break;
		}

		return currentColor;
	}

	public int getCurrentColor() {
		return currentColor;
	}
}

public class TrafficLightApplet extends Applet {

	private TrafficLightCanvas trafficLightCanvas = new TrafficLightCanvas();

	public void init() {

		setLayout(new GridLayout(1, 1));
		add(trafficLightCanvas);
	}

	public void start() {

		trafficLightCanvas.start();
	}

	public void stop() {

		trafficLightCanvas.stop();
	}
}

class TrafficLightCanvas extends Canvas implements Runnable {

	private TrafficLight trafficLight = new TrafficLight();
	private Thread runner;

	private final static int RED_SECS = 15;
	private final static int YELLOW_SECS = 5;
	private final static int GREEN_SECS = 15;

	private final String redLabel = "red";
	private final String yellowLabel = "yellow";
	private final String greenLabel = "green";
	private final String changeLabel = "change";
	private final String startLabel = "start";

	TrafficLightCanvas() {

		setBackground(Color.white);
	}

	public void run() {

		// Make sure the traffic light starts out as red
		while (trafficLight.getCurrentColor() != TrafficLight.RED) {
			trafficLight.change();
		}

		for (;;) {

			repaint();

            try {
                Thread.sleep(getSecs());
            }
            catch (InterruptedException e) {
            }

			trafficLight.change();
		}
	}

	private int getSecs() {

		switch (trafficLight.getCurrentColor()) {

		case TrafficLight.RED:
		default:

			return RED_SECS * 1000;

		case TrafficLight.YELLOW:

			return YELLOW_SECS * 1000;

		case TrafficLight.GREEN:

			return GREEN_SECS * 1000;
		}
	}

	public void start() {

		runner = new Thread(this);
		runner.start();
	}

	public void stop() {

		if (runner != null) {

			runner.stop();
			runner = null;
		}
	}

    public void paint(Graphics g) {

		Dimension dim = size();
		int circleDiameter = dim.height / 4;
		int circleRadius = dim.height / 8;
		int quarterCircleDiameter = dim.height / 16;

		int xCircleStart = (dim.width / 2) - circleRadius;
		int yRedCircleStart = circleRadius / 2;
		int yYellowCircleStart = circleDiameter + circleRadius;
		int yGreenCircleStart = (3 * circleDiameter) - (circleRadius / 2);

		// Fill in one circle
		switch (trafficLight.getCurrentColor()) {

		case TrafficLight.RED:
		default:

			g.setColor(Color.red);
			g.fillOval(xCircleStart, yRedCircleStart, circleDiameter, circleDiameter);
			break;

		case TrafficLight.YELLOW:

			g.setColor(Color.yellow);
			g.fillOval(xCircleStart, yYellowCircleStart, circleDiameter, circleDiameter);
			break;

		case TrafficLight.GREEN:

			g.setColor(Color.green);
			g.fillOval(xCircleStart, yGreenCircleStart, circleDiameter, circleDiameter);
			break;
		}

		// Draw outlines of circles
		g.setColor(Color.black);
		g.drawOval(xCircleStart, yRedCircleStart, circleDiameter, circleDiameter);
		g.drawOval(xCircleStart, yYellowCircleStart, circleDiameter, circleDiameter);
		g.drawOval(xCircleStart, yGreenCircleStart, circleDiameter, circleDiameter);

		int yCenterRedCircle = (3 * circleDiameter) / 4;
		int yCenterYellowCircle = 2 * circleDiameter;
		int yCenterGreenCircle = (3 * circleDiameter) + (circleDiameter / 4);

		// Draw arcs for arrow bodies
		g.drawArc(xCircleStart - circleDiameter, yCenterRedCircle, circleDiameter * 2, (2 * circleDiameter) + circleRadius, 90, 180);
		g.drawArc(xCircleStart, yCenterRedCircle, circleDiameter * 2, circleDiameter + (circleDiameter / 4), 90, -180);
		g.drawArc(xCircleStart, yCenterYellowCircle, circleDiameter * 2, circleDiameter + (circleDiameter / 4), 90, -180);
		g.drawArc(xCircleStart - circleDiameter, yRedCircleStart - circleRadius, circleDiameter * 2, circleDiameter, 180, 90); // (the start arrow)

		// Create polygons for the arrow heads
		Polygon toRedArrowHead = new Polygon();
		toRedArrowHead.addPoint(xCircleStart + circleDiameter, yCenterRedCircle);
		toRedArrowHead.addPoint(xCircleStart + circleDiameter + quarterCircleDiameter, yCenterRedCircle - (quarterCircleDiameter / 2));
		toRedArrowHead.addPoint(xCircleStart + circleDiameter + quarterCircleDiameter, yCenterRedCircle + (quarterCircleDiameter / 2));

		Polygon toYellowArrowHead = new Polygon();
		toYellowArrowHead.addPoint(xCircleStart + circleDiameter, yCenterYellowCircle);
		toYellowArrowHead.addPoint(xCircleStart + circleDiameter + quarterCircleDiameter, yCenterYellowCircle - (quarterCircleDiameter / 2));
		toYellowArrowHead.addPoint(xCircleStart + circleDiameter + quarterCircleDiameter, yCenterYellowCircle + (quarterCircleDiameter / 2));

		Polygon toGreenArrowHead = new Polygon();
		toGreenArrowHead.addPoint(xCircleStart, yCenterGreenCircle);
		toGreenArrowHead.addPoint(xCircleStart - quarterCircleDiameter, yCenterGreenCircle - (quarterCircleDiameter / 2));
		toGreenArrowHead.addPoint(xCircleStart - quarterCircleDiameter, yCenterGreenCircle + (quarterCircleDiameter / 2));

		Polygon startArrowHead = new Polygon();
		startArrowHead.addPoint(xCircleStart, yCenterRedCircle);
		startArrowHead.addPoint(xCircleStart - quarterCircleDiameter, yCenterRedCircle - (quarterCircleDiameter / 2));
		startArrowHead.addPoint(xCircleStart - quarterCircleDiameter, yCenterRedCircle + (quarterCircleDiameter / 2));

		// Draw arrowheads
		g.fillPolygon(toRedArrowHead);
		g.fillPolygon(toYellowArrowHead);
		g.fillPolygon(toGreenArrowHead);
		g.fillPolygon(startArrowHead);

		Font font = getFont();
		FontMetrics fm = getFontMetrics(font);

		int widthRedString = fm.stringWidth(redLabel);
		int widthYellowString = fm.stringWidth(yellowLabel);
		int widthGreenString = fm.stringWidth(greenLabel);
		int widthChangeString = fm.stringWidth(changeLabel);
		int widthStartString = fm.stringWidth(startLabel);
		int labelHeight = fm.getAscent() + fm.getDescent();

		// Label the circles
		g.drawString(redLabel, xCircleStart + circleRadius - (widthRedString / 2), yCenterRedCircle + (labelHeight / 2) - fm.getDescent());
		g.drawString(yellowLabel, xCircleStart + circleRadius - (widthYellowString / 2), yCenterYellowCircle + (labelHeight / 2) - fm.getDescent());
		g.drawString(greenLabel, xCircleStart + circleRadius - (widthGreenString / 2), yCenterGreenCircle + (labelHeight / 2) - fm.getDescent());

		// Write the ch-ch-ch-changes
		g.drawString(changeLabel, xCircleStart - circleDiameter - quarterCircleDiameter - widthChangeString, yCenterYellowCircle + (labelHeight / 2) - fm.getDescent());
		g.drawString(changeLabel, xCircleStart + (2 * circleDiameter) + quarterCircleDiameter, ((yCenterRedCircle + yCenterYellowCircle) / 2) + (labelHeight / 2) - fm.getDescent());
		g.drawString(changeLabel, xCircleStart + (2 * circleDiameter) + quarterCircleDiameter, ((yCenterYellowCircle + yCenterGreenCircle) / 2) + (labelHeight / 2) - fm.getDescent());

		// Write the start label
		g.drawString(startLabel, xCircleStart - circleDiameter - quarterCircleDiameter - widthStartString, yCenterRedCircle - (circleRadius / 2) + (labelHeight / 2) - fm.getDescent());
	}
}