// mas964 ps4
// base class for animation, uses two mouseclicks and then starts off
// an animation, calling drawFrame(time) governed by timings..

// the two mouseclicks stuff should be abstracted from the general
// animator, but there are some bugs in the animator, it's dropping
// a few milliseconds.

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

public abstract class TwoPointAnimator extends DoubleBufferApplet implements Runnable {
  protected int frameDelay, animationLength;
  protected long startTime;
  protected Thread animatorThread;
  protected boolean threadDebugInfo = false; 
  
  protected int numButtonsPressed = 0;
  protected int x1, y1, x2, y2;

  // millisecond timings. Length <= 0 means never stop.
  // these values are also read from "length" and "delay" properties
  protected void setTiming(int delay, int length) {
    frameDelay = delay;
    animationLength = length;
  }

  // this is called with how many milliseconds we are into the animation
  public abstract void drawFrame(int ms);
  
  public boolean mouseDown(Event e, int x, int y) {
    if (numButtonsPressed == 0) {
      x1 = x;
      y1 = y;
      numButtonsPressed++;
    } else if (numButtonsPressed == 1) {
      x2 = x;
      y2 = y;
      numButtonsPressed++;
      stop();					  // kill anything running
      start();
      numButtonsPressed = 0;
    } else {
      System.out.println("Logic error - too many buttons pressed.");
    }
    return true;
  }
  
  public void start() {
    if (threadDebugInfo)
      System.out.println("Start was called " + System.currentTimeMillis());

    if (frameDelay == 0)			  // should throw an exception
      System.out.println("Start was called with a 0 frame delay!");

    if (numButtonsPressed == 2) {
      animatorThread = new Thread(this);
      animatorThread.start();
    }
  }

  public void stop() {
    if (threadDebugInfo)
      System.out.println("Stop was called " + System.currentTimeMillis());
    if (animatorThread != null) {
      animatorThread.stop();
      animatorThread = null;
    }
  }
  
  public void run() {
    if (threadDebugInfo)
      System.out.println("Running." + System.currentTimeMillis());
    startTime = System.currentTimeMillis();

    while (Thread.currentThread() == animatorThread) {
      long drawStartTime = System.currentTimeMillis();
      drawFrame((int)(drawStartTime - startTime));
      if (animationLength > 0 && drawStartTime - startTime >= animationLength)
	stop();
      else {
	try {
	  // sleep to the next frameDelay'th interval after beginning.
	  int delay = (int)(frameDelay - (System.currentTimeMillis() - drawStartTime));
	  if (delay < 0)
	    delay = delay % frameDelay + frameDelay; // first postive modulus
	  Thread.sleep(delay);
	} catch (InterruptedException e) {
	  System.out.println("Sleep interrupted?");
	}
      }
    }
  }

  // read in the frame delay and length parameters.
  public void init() {
    String delayString = getParameter("delay");
    String lengthString = getParameter("length");
    try {
      if (delayString != null)
	frameDelay = Integer.parseInt(delayString);
    } catch (Exception e) {}
    try {
      if (lengthString != null)
	animationLength = Integer.parseInt(lengthString);
    } catch (Exception e) {}
    super.init();
  }
}