/***********************************************************/
/*   CodePanel class                                       */
/* A MergeSort demonstration algorithm                     */
/* By JungSig Min attending Myong Ji University            */
/***********************************************************/


class CodePanel extends Panel {
  
  static final int marginX = 20;                 //constant variables for the positions
  static final int marginY = 10;                 //  for code panel
  static final int offsetX = 1;
  static final int offsetY = 1;
  static final int none    = -1;
  String code [];
  String explanations [];
  Font font = new Font ("TimesRoman", Font.PLAIN, 14);
  int lineHeight;
  int baseLine;
  int maxWidth = 0;
  int highlightedLine = none;
  Label explanation = new Label ();
  Applet applet;
  Color backgroundColor= new Color(24,255,208);
  Color explainColor = Color.gray;

  //constructor for  CodePanel
  public CodePanel (String code [], String explanations [], Applet applet) {
    this.code = code;
    this.explanations = explanations;
    this.applet = applet;
    setBackground (backgroundColor);
    explanation.setBackground (explainColor);
    add (explanation);
    explanation.hide ();
  }
  
  //preferredSize
  public Dimension preferredSize () {
    return new Dimension (maxWidth + 2 * marginX
                          , code.length * lineHeight + 2 * marginY);
  }
  
  //addNotify
  public void addNotify () {
    super.addNotify ();
    setFont (font);
    FontMetrics metrics = getFontMetrics (font);
    baseLine = metrics.getAscent ();
    lineHeight = baseLine + metrics.getDescent ();
    for (int i = 0; i < code.length; i++) {
      maxWidth = Math.max (maxWidth, metrics.stringWidth (code [i]));
    }
    maxWidth+=40;
  }
  
  //reset
  public void reset () {
    if (highlightedLine != none) {
      colorLine (highlightedLine, Color.white);
    }
    highlightedLine = none;
  }
  
  //highlight the currently executed line
  public void highlightLine (int line) {
    if (highlightedLine != none) {
      colorLine (highlightedLine, backgroundColor);
    }
    highlightedLine = line;
    if (highlightedLine != none) {
      colorLine (highlightedLine, Color.orange);
    }
  }
  
  //make color rectangle
  public void colorLine (int line, Color color) {
    Graphics g = getGraphics ();
    int y = marginY + line * lineHeight;
    g.setColor (color);
    g.fillRect (0, y, size ().width - 1, lineHeight);
    g.setColor (Color.black);
    g.drawString (code [line], marginX, y + baseLine);
  }
  
  //paint the code panel
  public void paint (Graphics g) {
    int y = marginY + baseLine;
    for (int i = 0; i < code.length; i++, y += lineHeight) {
      g.drawString (code [i], marginX, y);
    }
    highlightLine (highlightedLine);
  }
  
  //if there's mouseExit event
  public boolean mouseExit (Event event, int x, int y) {
    explanation.hide ();
    validate ();
    return true;
  }
  
  //if there's mouseUp event
  public boolean mouseUp (Event event, int x, int y) {
    int line = (y - marginY) / lineHeight;
    if ((line <= explanations.length)
        || (explanations [line].equals (""))) {
      explanation.setText (explanations [line]);
      explanation.setBackground (explainColor);
      explanation.setForeground (Color.black);
      explanation.validate ();
      explanation.show ();
    } 
    else {
      explanation.hide ();
    }
    validate ();
    explanation.move (marginX + offsetX
                      , marginY + offsetY + (line + 1) * lineHeight);
    return true;
  }
  
}