import java.applet.Applet;

public class Duke extends Thread {

//----------------------------------------------------
/** Duke is a Thread that has knowledge of the parent
 *  applet (highly coupled) and thus, may call the
 *  parent's repaint method.  Duke is mainly
 *  responsible for changing an index value into an
 *  image array.
 */

  public static final int SUSPEND = 1;
  public static final int STOP    = 2;
  public static final int RUN     = 0;
  private int state = RUN;
  private int tumbleDirection;
  private int index = 0;
  private int numImages;  
  private Applet parent=null;

  public Duke(int tumbleDirection, int numImages,
                                     Applet parent) {
    this.tumbleDirection = tumbleDirection;
    this.numImages = numImages;
    this.parent = parent;    
  }
    
  public int getIndex() { return index; }
    
  //--------------------------------------------------
  /** Public method to permit setting a flag to 
   *  stop or suspend the thread. State is monitored
   *  through corresponding checkState method.
   */    
  public synchronized void setState(int state) {
    this.state = state;
    if (state==RUN)
      notify();
  }
    
  //--------------------------------------------------
  /** Returns the desired state (RUN, STOP, SUSPEND) 
   *  of the thread.  If the thread is to be 
   *  suspended, then the thread method wait is 
   *  continuously called until the state is changed
   *  through the public method setState.
   */ 
  private synchronized int checkState() {
   	while (state==SUSPEND) {
      try { wait(); }
    	catch (InterruptedException e) {}
    }
    return state;
  }

  //----------------------------------------------------
  /** The variable index (into image array) is
   *  incremented once each time through the while
   *  loop, call repaint, and pauses for a moment. Each
   *  time through the loop the state (flag) of the 
   *  thread is checked.
   */    			
  public void run() {
    while ( checkState()!=STOP) { 
      index += tumbleDirection;
      if (index < 0) index = numImages - 1;
      if (index >= numImages) index = 0;

      parent.repaint();

      try { Thread.sleep(100); }
      catch (InterruptedException e)
      { break; }  // break while loop
    }
  }
}