import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;

import javax.swing.*;
import java.util.*;

class JogDial
  extends JComponent
  implements MouseListener,
             MouseMotionListener
{
  public static final int WIDTH = 400;
  public static final int HEIGHT = 200;
  
  public static final int OFFSET = 10;
  public static final int BAR_THICKNESS = 15;
  public static final int LINE_DIFFERENCE = 7;
  
  public static final int BEAD_WIDTH = 10;
  public static final int BEAD_HEIGHT = 25;

  protected int[] values = {-2,-1,0,1,2};
  
  protected int bead_x = WIDTH/2;
  protected int bead_y = OFFSET + (BAR_THICKNESS/2);

  protected int scroll_rate = 0;
  
  protected Vector listeners = new Vector();
  protected int id = 0;
  
  public JogDial()
  {
    super();
    this.addMouseListener(this);
    this.addMouseMotionListener(this);
  }
  
  protected boolean beadSelected = false;
  
  public void mouseEntered(MouseEvent e) {}
  public void mouseExited(MouseEvent e) {}
  public void mouseClicked(MouseEvent e) {}
  public void mousePressed(MouseEvent e) 
  {
    Rectangle bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH, BEAD_HEIGHT);
    beadSelected = bead.contains(e.getX(),e.getY());
  }
  
  public void mouseReleased(MouseEvent e) 
  {
    if (beadSelected)
    {
      beadSelected = false;
      this.snapBeadCenter();
      
      fire(0);
    }
  }

  public void mouseMoved(MouseEvent e) {}
  public void mouseDragged(MouseEvent e) 
  {
    if (beadSelected)
    {
      int old_bead_x = bead_x;
      
      //// this code can be written better...
      //// you can practice writing this better yourself :)
      
      if ((e.getX() >= this.OFFSET) &&
          (e.getX() < this.WIDTH - OFFSET))
      {
        Rectangle old_bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);
        this.bead_x = e.getX();
        Rectangle bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);
        
        repaint(old_bead);
        repaint(bead);
        
        if (scroll_rate != getValue(bead_x))
          fire(getValue(bead_x));
      }
      
      //// the following code was added...to have the bead all the way to the left 
      //// or all the way to the right when the mouse is moved off the component in
      //// that direction
      else if (e.getX() >= this.WIDTH - this.OFFSET)
      {
        Rectangle old_bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);
        this.bead_x = this.WIDTH - this.OFFSET - 1;
        Rectangle bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);
        
        repaint(old_bead);
        repaint(bead);
        
        if (scroll_rate != getValue(bead_x))
          fire(getValue(bead_x));
      }
      else if (e.getX() < this.OFFSET)
      {
        Rectangle old_bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);
        this.bead_x = this.OFFSET;
        Rectangle bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);
        
        repaint(old_bead);
        repaint(bead);
        
        if (scroll_rate != getValue(bead_x))
          fire(getValue(bead_x));
      }
      
      
    }
  }

  
  public void addScrollListener(ScrollListener l)
  {
    listeners.addElement(l);
  }
  
  public void removeScrollListener(ScrollListener l)
  {
    listeners.removeElement(l);
  }

  public void fire(int value)
  {
    //// TODO:
    ////
    //// think about how this can be done in a way that
    //// would not affect the user's interaction with the component
    //// when one of the scroll listener takes a long time 
    //// handling the event.
    ////
    ScrollEvent e = new ScrollEvent(this,id++,value);
    for(int i=0; i<listeners.size(); i++)
    {
      ScrollListener l = (ScrollListener) listeners.elementAt(i);
      l.scrollAt(e);
    }

    scroll_rate = value;
  }
  
  public int getValue(int x)
  {
    //// i added this code so that when the segments are scroll values
    //// rather than needing to hit the bars to get that scroll value
    ////
    //// this bit of code takes the values array (-2,-1,0,-1,-2)
    //// and removes the 0
    ////
    //// the 0 scroll rate is only ever achieve when the bead is released
    //// and snapped to center
    ////
    //// if it moves to the left of the center, then scroll rate is -1
    //// if it moves to the right of the center, then scroll rate is 1
    //// etc.
    int[] segments = new int[values.length - 1];
    int j = 0;
    for (int i=0; i<values.length; i++)
      if (values[i] != 0)
        segments[j++] = values[i];
    
    Dimension size = getSize();
    Rectangle bar = new Rectangle(OFFSET,OFFSET,size.width-2*OFFSET,BAR_THICKNESS);
    int segment_size = bar.width / (values.length - 1);
    
    int index = -1;
    
    for (int i=0; i<values.length-1; i++)
    {
      if (((i * segment_size) + OFFSET <= x) &&
          (x < ((i+1) * segment_size) + OFFSET))
      {
        index = i;
        break;
      }
    }

    return(segments[index]);
  }
  
  
  
  public Dimension getMinimumSize()
  {
    return(new Dimension(WIDTH,HEIGHT));
  }
  
  public Dimension getPreferredSize()
  {
    return(this.getMinimumSize());
  }
  
  public void drawBead(Graphics2D g2)
  {
    Rectangle bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH, BEAD_HEIGHT);
    
    g2.setColor(Color.gray);
    g2.fill(bead);
    g2.setColor(Color.black);
    g2.draw(bead);
    
  }

  
  protected void moveBeadRight()
  {
    if (bead_x < this.WIDTH - OFFSET)
      bead_x++;

    /*
    Graphics g = getGraphics();
    drawBead((Graphics2D) g);  //// calls the function to draw the bead..
    g.dispose();
    */

    // not recommended
    // repaint();

    /*
    //// repaints damaged area
    Rectangle damaged = new Rectangle(bead_x - 1 - (BEAD_WIDTH/2), bead_y - (BEAD_HEIGHT/2), 1, BEAD_HEIGHT+1);
    repaint(damaged);
    */
    
    //// repaints new + damaged
    Rectangle bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);
    Rectangle damaged = new Rectangle(bead_x - 1 - (BEAD_WIDTH/2), bead_y - (BEAD_HEIGHT/2), 1, BEAD_HEIGHT+1);
    repaint(bead);
    repaint(damaged);
    /* 
    */
  }
  
  protected void snapBeadCenter()
  {
    Rectangle damaged = new Rectangle(bead_x - (BEAD_WIDTH/2), bead_y - (BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);

    bead_x = 200;

    /*
    Graphics g = getGraphics();
    drawBead((Graphics2D) g);  //// calls the function to draw the bead..
    g.dispose();
    */
    
    // not recommended
    // repaint();

    /*
    //// repaints damaged area
    repaint(damaged);
    */
    
    //// repaints new + damaged
    Rectangle bead = new Rectangle(bead_x - (this.BEAD_WIDTH/2), bead_y -(this.BEAD_HEIGHT/2), BEAD_WIDTH+1, BEAD_HEIGHT+1);
    repaint(bead);
    repaint(damaged);
    /*    
    */
  }
  
  
  
  
  
  
  
  
  public void paintComponent(Graphics g)
  {
    Graphics2D g2 = (Graphics2D) g;
    Dimension size = getSize();
    
//    Polygon p = new Polygon();
//    p.addPoint(x,y);

    Font font = new Font("Helvetica", Font.BOLD, 14);
    FontMetrics metrics = g2.getFontMetrics(font);
    
    Rectangle bar = new Rectangle(OFFSET,OFFSET,size.width-2*OFFSET,BAR_THICKNESS);

    g2.setColor(Color.black);
    g2.setFont(font);
    int segment_size = bar.width / (values.length - 1);
    for (int i=0; i<values.length; i++)
    {
      int line_x = bar.x + (i * segment_size);
      int line_low = bar.y + bar.height + this.LINE_DIFFERENCE;
      g2.drawLine(line_x, bar.y - this.LINE_DIFFERENCE, bar.x + (i * segment_size), line_low);
      
      Integer iValue = new Integer(values[i]);
      String strValue = iValue.toString();
      
      g2.drawString(strValue,line_x-(metrics.stringWidth(strValue)/2),line_low + metrics.getHeight());
    }

    g2.setColor(Color.white);
    g2.fill(bar);
    g2.setColor(Color.black);
    g2.draw(bar);
    
    drawBead(g2);
  }






}