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

public class ListTest extends Applet {
 
  LinkedList integerList;
  ListIterator cursor;
  int count;
  TextField messageArea;
  Button insertAfter, insertBefore, remove, clear, next, previous, enumerate, find;
  Panel buttons;
  int fontsize;  // default: 12 pt
  Font font; // Helvetica Bold
  FontMetrics fm;
  Color bgColor, fgColor, cursorColor; // defaults: white, black, red

  public void init () {
    // read parameters from HTML
    String str;
    try {
    str = getParameter("backgroundcolor");
    bgColor = (str != null) ? new Color(Integer.parseInt(str,16)) : getBackground();
    setBackground(bgColor);
    str = getParameter("foregroundcolor");
    fgColor = (str != null) ? new Color(Integer.parseInt(str,16)) : Color.black;
    setForeground(fgColor);
    str = getParameter("cursorcolor");
    cursorColor = (str != null) ? new Color(Integer.parseInt(str,16)) : Color.red;
    str = getParameter("fontsize");
    fontsize = (str != null) ? Integer.parseInt(str) : 12;
    font = new Font("Helvetica", Font.BOLD, fontsize);
    setFont(font);
    fm = getFontMetrics(font);
    }
    catch(Exception e) {
      System.out.println(e);
    }
    //
    integerList = new LinkedList();
    cursor = integerList.head();
    count = 1;
    messageArea = new TextField("");
    messageArea.setEditable(false);
    setLayout(new BorderLayout());
    buttons = new Panel();
    buttons.setLayout(new FlowLayout());
    insertAfter  = new Button("insertAfter");
    insertBefore = new Button("InsertBefore");
    remove = new Button("Remove");
    clear = new Button("Clear");
    next = new Button("Next");
    previous = new Button("Previous");
    enumerate = new Button("Enumerate");
    find = new Button("Find");
    buttons.add(insertAfter);
    buttons.add(insertBefore);
    buttons.add(remove);
    buttons.add(clear);
    buttons.add(new Label("       "));
    buttons.add(next);
    buttons.add(previous);
    buttons.add(new Label("       "));
    buttons.add(enumerate);
    buttons.add(find);
    add("North", buttons);
    add("South", messageArea);
  }
   
  public boolean action(Event evt, Object arg) {
    messageArea.setText("");
    if (evt.target == insertAfter) {
      try {  
        integerList.insertAfter(new Integer(count), cursor);
        count++;
      }
      catch(Exception e) {
        messageArea.setText(e.getMessage());      
      }
    }
    else if (evt.target == insertBefore) {
      try {
        integerList.insertBefore(new Integer(count), cursor);
        count++;
      }
      catch(Exception e) {
        messageArea.setText(e.getMessage());      
      }
    }
    else if (evt.target == remove) {
      try {
        integerList.remove(cursor);
        cursor.previous();
      }
      catch(Exception e) {
        messageArea.setText(e.getMessage());      
      }
    }
    else if (evt.target == clear) {
      integerList.clear();
      cursor.head();
      count = 1;
    }

    else if (evt.target == next) {
      cursor.next();
    }
    else if (evt.target == previous) {
      cursor.previous();
    }
    else if (evt.target == enumerate) {
      String str = "Current list: empty";
      Enumeration e = integerList.elements();  // get all list elements
      if (e.hasMoreElements()) {
        str = "Current list: ";
      }
      while (e.hasMoreElements()) {       // step through all list elements
        Integer obj = (Integer) e.nextElement();
        str = str + obj.toString() + " ";
      }
      messageArea.setText(str); 
    }
    else if (evt.target == find) {
      FindFrame ff = new FindFrame(this, "Find List Item");
      ff.show();
    }
    else {
      return super.action(evt, arg);
    }
    repaint();
    return true;
  }

  public void paint(Graphics g) {  
    int size = fm.stringWidth("1234");
    int x = 2*size;
    int y = 3*size;
    g.setColor(fgColor);      
    if (cursor.pos == integerList.head) {
       g.setColor(cursorColor);
       g.fillRect(x+1, y+1, size-1, size-1);
       g.setColor(fgColor);
    }
    g.drawRect(x, y, size, size);
    g.drawString("H", x + size/3, y + 2*size/3);
    x += size;
    //
    Enumeration e = integerList.elements();
    while (e.hasMoreElements()) {  
      Integer i = (Integer) e.nextElement();
      // draw right arrow
      g.drawLine(x, y + size/3, x + size, y + size/3);
      g.drawLine(x + size, y + size/3, x + 5*size/6, y + size/2);
      g.drawLine(x + size, y + size/3, x + 5*size/6, y + size/6);
      // draw left arrow
      g.drawLine(x + size, y + 2*size/3, x, y + 2*size/3);
      g.drawLine(x, y + 2*size/3, x + size/6, y + size/2);
      g.drawLine(x, y + 2*size/3, x + size/6, y + 5*size/6);
      //  draw box
      if (i.equals(cursor.pos.obj)) {
        g.setColor(cursorColor); 
        g.fillRect(x+size+1, y+1, size-1, size-1);
        g.setColor(fgColor);
      } 
      g.drawRect(x+size, y, size, size);
      x +=size;
      g.drawString(i.toString(), x + size/4, y + 2*size/3);
      x +=size; 
    }
    // draw right arrow
    int[] xcoordsR = {x, x+size , x+size, size, size, 2*size};
    int[] ycoordsR = {y+size/3, y+size/3, y+5*size/3, y+5*size/3, y+size/3, y+size/3};     
    g.drawPolygon(xcoordsR, ycoordsR, 6);
    g.drawLine(2*size, y+size/3, 11*size/6, y+size/6);
    g.drawLine(2*size, y+size/3,  11*size/6, y+size/2);
    // draw left arrow
    int[] xcoordsL = {x, x+2*size/3, x+2*size/3, 4*size/3, 4*size/3, 2*size};
    int[] ycoordsL = {y+2*size/3, y+2*size/3, y+4*size/3, y+4*size/3, y+2*size/3, y+2*size/3};  
    g.drawPolygon(xcoordsL, ycoordsL, 6);
    g.drawLine(x, y+2*size/3, x+size/6, y+size/2);
    g.drawLine(x, y+2*size/3, x+size/6, y+5*size/6);
  }
}