/*
 * Walker.java
 * Created on Feb 21, 2005
 */
package random;

import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JApplet;
import javax.swing.Timer;

import ptolemy.plot.Plot;

/**
 * A random walker.
 */
public final class WalkerApplet extends JApplet implements ActionListener {

    private static final int NUM_POINTS = 1000;
    private static final int MAX_Y_DEV  = 60;
    private static final int NUM_DATASETS = 10;
    private static final int STEPS_PER_INTERVAL = 100;
    private static final int INTERVAL_MS = 25;

    private LFSR rng = new LFSR();
    private Plot plot = new Plot();
    private int time = 0;
    private int[] xValues = new int[NUM_DATASETS];
    private Timer timer = new Timer(INTERVAL_MS, this);

    public void init() {
        plot.setTitle("1D Random Walkers");
        plot.setXLabel("t");
        plot.setXRange(0, NUM_POINTS);
        plot.setYLabel("x");
        plot.setYRange(-MAX_Y_DEV, MAX_Y_DEV);

        Container contentPane = getContentPane();
        contentPane.add(plot);
    }

    public void start() {
        timer.start();
    }

    public void actionPerformed(ActionEvent e) {
        // add an error bar
        if (time > 0 && time <= NUM_POINTS) {
            double barDev = 1.5 * Math.sqrt(time);
            plot.addPointWithErrorBars(0, time, xValues[0], -barDev, barDev, true);
        }
        
        // stop the timer if time is up
        if (time >= NUM_POINTS) timer.stop();

        // plot some points
        for(int t = 0; t < STEPS_PER_INTERVAL && time < NUM_POINTS; t++, time++) {
            for(int i = 0; i < NUM_DATASETS; i++) {
                plot.addPoint(i, time, xValues[i], true);
                int delta = rng.nextBoolean() ? 1 : -1;
                xValues[i] += delta;
            }
        }

        // repaint the plot
        repaint();
    }

}