//
// File:        SkipListApplet.java
//
// Language:    Java 1.02
// Description: Class for a Applet that demonstrates a "SkipList" proposed by William Pugh
//
// Author:  Thomas Wenger, Jan-7-1998
//

import java.awt.*;
import java.applet.*;


public class SkipListApplet extends Applet {


  //
  // constructor:
  //
  public SkipListApplet() {
    mySkipList = new SkipList(0.5f, 6);
    mySkipListRenderer = new SkipListRenderer(this, mySkipList);
  }


  //
  // init():  is called by Webbrowser when started first time
  //
  public void init() {
    // build the GUI:
    setLayout(new BorderLayout());

    Panel p0 = new Panel();
    p0.add(new Label("SkipList Demonstration     (C) 1997 Thomas Wenger      "));
    p0.add(myRandomizeButton = new Button("Insert 10 Random nodes"));
    p0.add(myResetButton = new Button("Reset"));
    
    add("North",p0);
    add("Center",mySkipListRenderer);

    Panel p1 = new Panel();
    p1.add(new Label("Key:"));
    p1.add(myKeyTextField = new TextField(6));
    p1.add(new Label("Value:"));
    p1.add(myValueTextField = new TextField(6));
    myKeyTextField.setText("");
    myValueTextField.setText("0");

    p1.add(myInsertButton = new Button("Insert"));
    p1.add(mySearchButton = new Button("Search"));
    p1.add(myDeleteButton = new Button("Delete"));
    p1.add(new Label("Result:"));
    p1.add(myOutputTextField = new TextField(35));

    Panel p = new Panel();
    p.setLayout(new BorderLayout());
    p.add("North",myScrollbar = new Scrollbar(Scrollbar.HORIZONTAL,0,250,0,1000));
    p.add("South",p1);

    add("South",p);
  }


  //
  // handleEvent():  is called by AWT event handling mechanism for all events
  //
  public boolean handleEvent(Event  ev) {
    //
    // scrollbare moved:
    //
    if (ev.target == myScrollbar) {
      if (ev.id == Event.SCROLL_LINE_UP || ev.id == Event.SCROLL_LINE_DOWN ||
          ev.id == Event.SCROLL_PAGE_UP || ev.id == Event.SCROLL_PAGE_DOWN ||
          ev.id == Event.SCROLL_ABSOLUTE) {
        int pos = ((Integer)ev.arg).intValue();
        Rectangle bounds = mySkipListRenderer.bounds();
        int widthToScroll = mySkipListRenderer.calculateImageWidth()-bounds.width;
        widthToScroll = ( (widthToScroll<0) ? 0 : widthToScroll);
        int newOffset = (int)((-pos/1000f)*widthToScroll);
        mySkipListRenderer.setXOffset(newOffset);
        mySkipListRenderer.repaint();
        return true;
      }
    }    
    //
    // nothing processed:
    //
    return super.handleEvent(ev);
  }


  //
  // action():  is called by AWT event handling mechanism for ACTION events 
  //
  public boolean action(Event  ev, Object  obj) {
    //
    // insert pressed:
    //
    if (ev.target == myInsertButton) {
      int key = Integer.parseInt(myKeyTextField.getText());
      int value = Integer.parseInt(myValueTextField.getText());
      myKeyTextField.setText("");
      myValueTextField.setText("0");
      mySkipList.insert(key,value);
      myOutputTextField.setText("Node (k=" + key + ", v=" + value + ") inserted.");
      mySkipListRenderer.repaint();
      return true;
    }
    //
    // search pressed:
    //
    if (ev.target == mySearchButton) {
      int key = Integer.parseInt(myKeyTextField.getText());
      int value = mySkipList.search(key);
      myKeyTextField.setText("");
      myValueTextField.setText("0");
      if (value != SkipList.NOT_FOUND) {
        myOutputTextField.setText("Found: Node (k=" + key + ", v=" + value + ")");
      }
      else {
        myOutputTextField.setText("Not found: Node with k=" + key);
      }
      return true;
    }
    //
    // delete pressed:
    //
    if (ev.target == myDeleteButton) {
      int key = Integer.parseInt(myKeyTextField.getText());
      int value = mySkipList.search(key);
      myKeyTextField.setText("");
      myValueTextField.setText("0");
      if (value != SkipList.NOT_FOUND && key != Integer.MAX_VALUE) {
        mySkipList.delete(key);
        myOutputTextField.setText("Deleted: Node (k=" + key + ", v=" + value + ")");
        mySkipListRenderer.repaint();
      }
      else {
        myOutputTextField.setText("Not deleted: No node with k=" + key);
      }
      return true;
    }
    //
    // randomize insertion button pressed:
    //
    if (ev.target == myRandomizeButton) {
      for (int i=0; i<10; i++) {
        int key = (int)(Math.random()*100);
        int value = (int)(Math.random()*100);
        mySkipList.insert(key,value);
      }
      myOutputTextField.setText("10 random nodes inserted");
      mySkipListRenderer.repaint();
      return true;
    }
    //
    // reset button pressed:
    //
    if (ev.target == myResetButton) {
      mySkipList = new SkipList(0.5f, 6);
      mySkipListRenderer.setSkipList(mySkipList);
      mySkipListRenderer.setXOffset(0);
      mySkipListRenderer.repaint();
      myScrollbar.setValue(0);
      myOutputTextField.setText("List reseted.");
      return true;
    }
    //
    // nothing processed:
    //
    return super.action(ev,obj);
  }


  //
  // mouseDown():  is called by AWT event handling mechanism for mouse events 
  //
  public boolean mouseDown(Event ev, int x, int y) {
    if (ev.target == mySkipListRenderer) {
      SkipListElement element = mySkipListRenderer.findElementAt(x,y);
      if (element != null && element.key>=0 && element.key<Integer.MAX_VALUE) {
        myKeyTextField.setText(Integer.toString(element.key));
        myValueTextField.setText(Integer.toString(element.value));
        myOutputTextField.setText("Node selected.");
      }
      return true;
    }
    return false;
  }


  //
  // members:
  //
  private SkipListRenderer mySkipListRenderer;
  private SkipList mySkipList;
  private TextField myKeyTextField;
  private TextField myValueTextField;
  private TextField myOutputTextField;
  private Button myInsertButton;
  private Button mySearchButton;
  private Button myDeleteButton;
  private Button myRandomizeButton;
  private Button myResetButton;
  private Scrollbar myScrollbar;
}