import Particle;
import java.awt.*;
import java.applet.*;
import java.lang.Math;

public class ColorStrip extends DoubleBufferApplet implements Runnable {
  float hue = (float)0.5, goalHue = hue, hueV = 0;
  float sat = (float)0.5, goalSat = sat, satV = 0;
  int oldX, oldY;

  Thread animThread;
  int frameDelay = 250;
  
  public void init() {
    this.setBackground(Color.white);
    this.setForeground(Color.black);
    update(getGraphics());

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

  public void redrawImage() {
    int i;
    Graphics g = imageBuffer.getGraphics();
    for (i = 0; i < imageBufferSize.width + imageBufferSize.height + 1; i++) {
      float h = (float)i / (imageBufferSize.width + imageBufferSize.height);
      h = h + hue;
      while (h < 0)
	h += 10000;				  // overkill
      h = (h - (int)h);			  // 0 - 1
      g.setColor(Color.getHSBColor(h, sat, 1));
      g.drawLine(i, 0, 0, i);
    }
  
    g.setColor(Color.black);
    int x, y;
    x = (int)((hue - (int)hue) * imageBufferSize.width);
    g.drawLine(x, 0, x, imageBufferSize.height);
    y = (int)((sat - (int)sat) * imageBufferSize.height);
    g.drawLine(0, y, imageBufferSize.width, y);

    x = (int)((goalHue - (int)goalHue) * imageBufferSize.width);
    y = (int)((goalSat - (int)goalSat) * imageBufferSize.height);
    g.fillRect(x - 2, y - 2, 5, 5);
    
    repaint();
  }

  public void run() {
    while (Thread.currentThread() == animThread) {
      boolean needRedraw = false;
	 
      if (hueV > 0.002 || hueV < -0.002) {
	hue += hueV;				  // still some hue motion
	needRedraw = true;
      } else {
	if (hue != goalHue) {
	  hue = goalHue;			  // fake the rest
	  needRedraw = true;
	}
      }
      if (satV > 0.002 || satV < -0.002) {
	sat += satV;
	needRedraw = true;			  // still some sat motion
      } else {
	if (sat != goalSat) {
	  sat = goalSat;			  // fake the rest
	  needRedraw = true;
	}
      }
      if (needRedraw)				  // need to redraw? (slow)
	redrawImage();

      // if going the wrong way, reverse and damp
      if (hue - goalHue > 0.0 && hueV > 0)
	hueV = -hueV * 2/3;
      if (hue - goalHue < -0.0 && hueV < 0)
	hueV = -hueV * 2/3;

      if (sat - goalSat > 0.0 && satV > 0)
	satV = -satV * 2/3;
      if (sat - goalSat < -0.0 && satV < 0)
	satV = -satV * 2/3;
	  
      try {
        Thread.sleep(frameDelay);
      } catch (InterruptedException ex) {
        System.out.println("Sleep Interrupted??");
      }
    }
  }
      
  public void start() {
    super.start();
    animThread = new Thread(this);
    animThread.start();
  }

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

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

  // drag resets the goal, also adds a bit of velocity
  public boolean mouseDrag(Event e, int x, int y) {
    int deltaX = (x - oldX);
    if (deltaX != 0) {
      goalHue += ((float)deltaX / imageBufferSize.width);
      hueV += ((float)deltaX / (imageBufferSize.width * 5)) ;
    }

    int deltaY = (y - oldY);
    if (deltaY != 0) {
      goalSat += ((float)deltaY / imageBufferSize.height);
      satV += ((float)deltaY / (imageBufferSize.height * 5)) ;
    }

    oldX = x;
    oldY = y;

    return true;
  }

  // start/stop threads
  public boolean keyDown(Event e, int key) {
    if ((char)key == ' ') {
      if (animThread == null) {
        animThread = new Thread(this);
        animThread.start();
      } else {
        animThread = null;
      }
    }
    return true;
  }
}