// Client that implements a connected web of particles
// Colours of particles decay with inactivity

import java.awt.*;
import java.util.Vector;
import java.util.Enumeration;
import PS10Applet;

public class ParticleClient extends PS10Applet implements Runnable {
  Thread animThread;
  Vector particleList;
  int frameDelay = 100;
  int frameNumber = 0;
  Color grey50;
  
  public void init() {
    super.init();
    this.setBackground(Color.white);
    this.setForeground(Color.black);
    update(getGraphics());                        // force window create

    String frameDelayString = getParameter("frameDelay");
    try {
      if (frameDelayString != null)
        frameDelay = Integer.parseInt(frameDelayString);
    } catch (Exception e) {}

    String otherServerHost = getParameter("serverHost");
    if (otherServerHost != null)
      serverHost = otherServerHost;
    
    grey50 = new Color(.5f, .5f, .5f);
    particleList = new Vector(20);

  }

  public boolean mouseDown(Event e, int x, int y) {
    sendMessage(x, y);
    return true;
  }

  // when we get our ID set, move ourselves to the center.
  // also looks like we "create" the particle for ourselves.
  public void setID(int id) {
    super.setID(id);
    sendMessage(imageBufferSize.width / 2, imageBufferSize.height / 2);
  }

  public void receiveMessage(int otherID, int x, int y) {
    // System.out.println("Applet received " + otherID + " " + x + " " + y);
    if (x < 0 && y < 0)				  // ignore negatives
      return;

    // look to see if we already have a particle for this ID
    boolean oldParticle = false;
    Enumeration e = particleList.elements();
    while (e.hasMoreElements() && !oldParticle) {
      IDParticle p = (IDParticle)e.nextElement();
      if (p.id == otherID) {
	oldParticle = true;
	p.setGoal(x, y);
	p.setTime(System.currentTimeMillis());
      }
    }
    // no particle - make one!
    if (oldParticle == false) {
      Rectangle size = new Rectangle(0, 0, imageBufferSize.width, imageBufferSize.height);
      IDParticle p = new IDParticle(size, x, y, 0, 0, 0, 0, otherID);
      p.setGoal(x, y);
      p.setTime(System.currentTimeMillis());
      p.setHue((otherID % 8) / 8.0f);
      particleList.addElement(p);
    }
  }

  public void redrawImage() {
    clearImageBuffer();
    Graphics g = imageBuffer.getGraphics();
    g.setColor(Color.black);
    g.drawRect(0, 0, imageBufferSize.width - 1, imageBufferSize.height - 1);
    g.setColor(Color.white);
    long now = System.currentTimeMillis();
    int maxAge = 30000;	  // milliseconds

    int n = particleList.size();
    for (int i = 0; i < n; i++) {
      IDParticle p = (IDParticle)particleList.elementAt(i);
      for (int j = i + 1; j < n; j++) {
	long age;
	IDParticle p2 = (IDParticle)particleList.elementAt(j);
	
	// age is the older of the two, in milliseconds
	if (p.lastTime < p2.lastTime)
	  age = (int)(now - p.lastTime);
	else
	  age = (int)(now - p2.lastTime);
      
	if (age < maxAge) {
	  float normAge = (float)age / maxAge;
	  float grey = 1 - ((1 - normAge) * (1 - normAge));
	  g.setColor(new Color(grey, grey, grey));
	  drawThickLine(g, (int)p.x, (int)p.y, (int)p2.x, (int)p2.y, 7);
	}
      }
    }

    for (int i = 0; i < n; i++) { 
      IDParticle p = (IDParticle)particleList.elementAt(i);
      int age = (int)(now - p.lastTime);
      if (age > maxAge)
	continue;				  // don't even draw it.
      float normAge = (float)age / maxAge;
      float s;
      if (normAge < 1)
	s = ((1 - normAge) * (1 - normAge));
      else
	s = 0;
      
      g.setColor(Color.black);
      thickCenteredCircle(g, (int)p.x, (int)p.y, 14, 4, new Color(1-s, 1-s, 1-s), Color.getHSBColor(p.hue, s, 1));
    }
    repaint();
  }

  
  
  public void run() {
    while (Thread.currentThread() == animThread) {
      frameNumber++;
      redrawImage();

      Enumeration e = particleList.elements();
      while (e.hasMoreElements()) {
	Particle p = (Particle)e.nextElement();
	p.step(1.0);
      }

      try {
	Thread.sleep(frameDelay);
      } catch (InterruptedException ex) {};
    }
  }

  public void start() {
    super.start();
    animThread = new Thread(this);
    animThread.start();
  }

  public void stop() {
    animThread = null;
    super.stop();
  }

  public void thickCenteredCircle(Graphics g, int x, int y, int radius, int thickness, Color c1, Color c2) {
    g.setColor(c1);
    g.fillOval(x - radius, y - radius, radius * 2 + 1, radius * 2 + 1);
    g.setColor(c2);
    g.fillOval(x - (radius - thickness), y - (radius - thickness),
               (radius - thickness) * 2 + 1, (radius - thickness) * 2 + 1);
  }

  // this code isn't 100% correct, but it's close
  // don't know what the caps are doing
  public void drawThickLine(Graphics g, int x1, int y1, int x2, int y2, int thick) {
    int i;
    int off = Math.round(thick/2);

    for (i = 0; i < thick; i++) {
      g.drawLine(x1 - off + i, y1, x2 - off + i, y2);
      g.drawLine(x1, y1 - off + i, x2, y2 - off + i);
    }
  }
}