/**
  Program:   ThermometerMVC1 applet
  Purpose:   To illustrate the model-view-controller paradigm in Java.
  @author    Steve A. Chervitz (sac@genome.stanford.edu)
             Adapted from David Geary's example in Java Report 2(1):31-37.
  @version   3 Mar 1997
             This example encapsulates a minimal model, view and a controller
             to illustrate and experiment with the basics. 
*/

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


public class ThermometerMVC1 extends java.applet.Applet 
{
  private TemperatureView        tempView;
  private TemperatureController1 tempController;

  public void init() 
    { 
      final TemperatureView tempView = new TemperatureView();
      final TemperatureController tempController = new TemperatureController();

      setFont(new Font("Helvetica",Font.BOLD, 16));
      setForeground(Color.black);
      add( new Label("ThermometerMVC1: Illustrating the Model-View-Controller in Java"));

      Panel p_model = new Panel();
      p_model.setLayout( new BorderLayout());
      p_model.add("North", new Label("Model"));
      TextArea ta = new TextArea(tempController.getModel().toString(),5,40);
      ta.setFont( new Font("Helvetica",Font.PLAIN, 14));
      ta.setEditable( false);
      p_model.add("Center",ta);

      Panel p_view = new Panel();
      p_view.setLayout( new BorderLayout());
      p_view.add("North", new Label("View"));
      p_view.add("Center",tempView);

      Panel p_controller = new Panel();
      p_controller.setLayout( new BorderLayout());
      p_controller.add("North", new Label("Controller"));
      p_controller.add("Center",tempController);

      add( p_model);
      add( p_view);
      add( p_controller);
      
      tempController.addObserver(tempView);
    }
}


class TemperatureModel extends Observable 
{
  public static int MAX_TEMP_F=250, MIN_TEMP_F=0;
  private int fahrenheit, celcius;
  
  public TemperatureModel() {
    this(0);
  }
  
  public TemperatureModel(int temp) {
    setTemperature(temp);
  }
  
  public void setTemperature(int f) 
    {
      //    System.out.println("TemperatureModel.setTemperature("+f+")");
      
      if(f > MAX_TEMP_F) f = MAX_TEMP_F;
      else if(f < MIN_TEMP_F) f = MIN_TEMP_F;
      
      fahrenheit = f;
      celcius = (int) ((double)(fahrenheit-32)*5/9);
      setChanged();
      notifyObservers();
    }
  
  public int F() { return fahrenheit; }
  
  public int C() { return celcius; }
  
  public int K() { return celcius+273; }
  
  public String toString() {
    return "TemperatureModel: provides current temp\n"+
      "in fahrenheit, celcius, or Kelvin.\n"+
	"Max temp = "+MAX_TEMP_F+"F; Min temp ="+MIN_TEMP_F+"F\n"+
	  "setTemperature(int) expects fahrenheit.\n";
  }
}


/*-----------------------------------------------------*/
class TemperatureView extends Label implements Observer 
/*-----------------------------------------------------*/
{
  private Dimension preferredSize = new Dimension(350,20);
  
  public TemperatureView()
    {
      setText("Current temperature: ");
      setForeground(Color.red);
    }
  
  public Dimension preferredSize(){ return preferredSize; }
  
  public void update(Observable ob, Object arg)
    {
      TemperatureModel temp = (TemperatureModel)ob;
      
      setText("Current temperature: "+temp.F()+"F,   "+
	      temp.C()+"C,   "+temp.K()+"K");
    }
}


/*------------------------------------------*/
class TemperatureController1 extends Button
/*------------------------------------------*/
{
  private Dimension preferredSize = new Dimension(350,40);
  private TemperatureModel tempModel;
  private int maxTempF = TemperatureModel.MAX_TEMP_F;
  
  public TemperatureController1()
    {
      setForeground(Color.blue);
      setLabel("Switch temperature (0-"+maxTempF+"F)");
      
      tempModel = new TemperatureModel();
    }

  public Dimension preferredSize(){ return preferredSize; }

  public boolean action(Event evt, Object arg) 
  {
      tempModel.setTemperature((int)(Math.random()*maxTempF));

      return true;
    }    

  public void addObserver(Observer obs)
    {
      tempModel.addObserver(obs);
      //Initialize the view.
      obs.update(tempModel,this); 
    }
  
  public TemperatureModel getModel() { return tempModel; }

}