import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.io.*;

/** PolyClipApplet is an applet that animates a polygon clipping algorithm.*/
public class PolyClipApplet extends Applet implements Runnable {
  
  PolyClipCanvas canvas; //drawing area
  Button step; //The button that user clicks on to get algorithm to do next step
  Button start; //The button that user clicks on to get algorithm to start
  Checkbox stepMode; //So user can turn off single step execution
  boolean dontWait = false; //If true, we don't wait till step button pressed

  /** Thread that executes given algorithm */
  Thread runner;

  /** Start thread that executes given algorithm */
  public void start() {
    if (runner != null){
      /* let previous animation finish */
      dontWait = true;
      wakeUp();
      Thread.yield();
      dontWait = false;
    }
    runner = new Thread(this);
    runner.start(); //Run in separate thread so it can step
  }

  /** This is the method called when a thread is started
      being animated.
  */
  public void run() {
    //System.out.println("Polygon: "+polyToString(canvas.getPolygon()));
    //System.out.println("Rectangle: "+rectToString(canvas.getClipRectangle()));
    Polygon c = canvas.clipPolygon(canvas.getPolygon(),canvas.getClipRectangle());
    runner = null;
  }

  /** Make algorithm continue execution after step() has been called */
  synchronized void wakeUp() {
    notify();
  }

  /** Stop execution until "Step" button is pressed and
      display a message*/
  synchronized void step(String message) {
    if (dontWait) return;
    showStatus(message);
    try {
      if (stepMode.getState()) {
	wait();
      } else {
	Thread.sleep(1000); //wait one second
      }
    } catch (InterruptedException e) {
      /*nothing */
    }
  }


  /** init() is called by browser to initialize the applet */
  public void init() {
    setBackground(Color.white);
    setLayout(new BorderLayout());
    canvas = new PolyClipCanvas(this);
    add(canvas,"Center");

    Panel p = new Panel();

    /* When this button is clicked on the start method is called */
    start = new Button("Start");
    p.add(start);
    start.addActionListener( new ActionListener() {
      public void actionPerformed(ActionEvent e){
	start();
      }
    });

    /* When this button is clicked on the wakeUp method is called */
    step = new Button("Step");
    p.add(step);
    step.addActionListener( new ActionListener() {
      public void actionPerformed(ActionEvent e){
	wakeUp();
      }
    });

    /* No need to do anything when user changes state of the checkbox */
    stepMode = new Checkbox("Step Mode",true);
    p.add(stepMode);

    Button clear = new Button("Clear");
    p.add(clear);
    clear.addActionListener( new ActionListener() {
      public void actionPerformed(ActionEvent e){
	canvas.clear();
      }
    });
    add(p,"South");
  }

  public int getInt(StreamTokenizer st) throws IOException{
    while (st.nextToken() != StreamTokenizer.TT_EOF) {
      if (st.ttype == StreamTokenizer.TT_NUMBER) {
	return (int)st.nval;
      }
    }
    throw new EOFException("EOF while looking for an int");
  }

  public String polyToString(Polygon p){
    StringBuffer sb = new StringBuffer(p.npoints+" [");
    //find top leftmost point
    int topleftindex = 0;
    for (int i = 0; i < p.npoints; i++){
      if (p.xpoints[i] < p.xpoints[topleftindex] ||
          (p.xpoints[i] == p.xpoints[topleftindex] &&
	   p.ypoints[i] < p.ypoints[topleftindex])){
	topleftindex = i;
      }
    }
    
    for (int i = 0; i < p.npoints; i++){
      int j = (i+topleftindex) % p.npoints;
      sb.append("("+p.xpoints[j]+","+p.ypoints[j]+"),");
    }
    sb.setCharAt(sb.length()-1,']');
    return sb.toString();
  }

  public String rectToString(Rectangle r){
    return r.x + " " + r.y + " " + r.width + " " + r.height;
  }

  /* method for non-interactive testing of PolyClipCanvas */
  public void test(){
    dontWait = true;
    Polygon p = new Polygon();
    Rectangle r = new Rectangle();
    canvas = new PolyClipCanvas(this);
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    StreamTokenizer st = new StreamTokenizer(in);
    try {
      while (st.nextToken() != StreamTokenizer.TT_EOF) {
	if (st.ttype == StreamTokenizer.TT_WORD &&
	    st.sval.equals("Polygon")) { //Define a polygon for clipping
	  p = new Polygon();
	  for (int n = getInt(st); n>0; n--){
	    p.addPoint(getInt(st),getInt(st));
	  }
	  System.out.println("Polygon "+polyToString(p));
	} else if (st.ttype == StreamTokenizer.TT_WORD &&
		   st.sval.equals("Rectangle")) { //Define a clip rectangle
	  r = new Rectangle(getInt(st),getInt(st),getInt(st),getInt(st));
	  System.out.println("Rectangle "+rectToString(r));
	} else if (st.ttype == StreamTokenizer.TT_WORD &&
		   st.sval.equals("Clip")) { //Clip the polygon and print the result
	  Polygon clip = canvas.clipPolygon(p,r);
	  System.out.println("Clipped "+polyToString(clip));
	} else if (st.ttype == StreamTokenizer.TT_WORD &&
		   st.sval.equals("GetClipRectangle")) {//Print the clip rectangle defined by the canvas
	  r = canvas.getClipRectangle();
	  System.out.println("Rectangle "+rectToString(r));
	} else if (st.ttype == StreamTokenizer.TT_WORD &&
		   st.sval.equals("Frame")) {//create a frame so that the canvas can draw on screen
	  Frame f = new Frame();
	  f.setSize(300,300);
	  f.add(canvas);
	  f.setVisible(true);
	} else if (st.ttype == StreamTokenizer.TT_WORD &&
		   st.sval.equals("MouseEvent")) {//send a mouse event to canvas
	  MouseEvent e = new MouseEvent(canvas,getInt(st),
					0,getInt(st),getInt(st),getInt(st),
					1,false);
	  canvas.dispatchEvent(e);
	} else if (st.ttype == StreamTokenizer.TT_WORD &&
		   st.sval.equals("Quit")) {
	  System.exit(0);
	}
      }
    } catch (IOException e){
      System.err.println("Error on reading");
    }
  }


  public static void main(String[] args){
    PolyClipApplet applet = new PolyClipApplet();
    applet.setStub(new FakeAppletStub(""));
    applet.test();
  }


}