/**
  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.
	     Adapted by Andrew Walenstein for CMPT 318 class
  @version   3 Mar 1997
             This example encapsulates a minimal model, view and a controller
             to illustrate and experiment with the basics. 

<APPLET CODE=ThermometerMVC318.class WIDTH=480 HEIGHT=400></APPLET>

*/

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


public class ThermometerMVC318 extends java.applet.Applet 
{
  public void init() 
  { 
    // Model, View and Controller communicate through events:
    //   1.  Controller->Model ==> java.awt.Event through Listeners
    //         set up in Controller constructor
    //
    //   2.  Model->View ==> java.lang.Observer
    //         set up here after Model and View are constructed
    //
    final TempModel      tempModel      = new TempModel();
    final TempView       tempView       = new TempView();
    final TempController tempController = new TempController ( tempModel );

    tempModel.addObserver ( tempView );

    // Decorate
    {
      setForeground ( Color.black );

      // Static panel to display model info
      //
      final TextArea ta = new TextArea ( tempModel.toString(), 5, 40 );
      ta.setEditable ( false );

      final Panel infoPanel = new Panel();
      infoPanel.setLayout ( new GridLayout(2,1) );
      infoPanel.add ( new Label("Model") );
      infoPanel.add ( ta );

      setLayout ( new GridLayout(4,1) );
      add ( new Label("ThermometerMVC318: Illustrating the Model-View-Controller in Java"));
      add ( infoPanel );
    }

    add ( tempView.getPanel() );
    add ( tempController.getPanel() );
  }
}


class TempModel extends Observable 
{
  public static int MAX_TEMP_F = 250;
  public static int MIN_TEMP_F = 0;

  private int fahrenheit;
  private int celcius;
  
  public TempModel() { this(0); }

  public TempModel ( final int temp )
  {
    setTemperature ( temp );
  }

  final public void setTemperature ( int newTempF )
  {
    if ( newTempF > MAX_TEMP_F )
      {
	newTempF = MAX_TEMP_F;
      }
    else if ( newTempF < MIN_TEMP_F )
      {
	newTempF = MIN_TEMP_F;
      }

    this.fahrenheit = newTempF;
    this.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 "TempModel: 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 TempView implements Observer 
{
  private final Label myLabel;
  private final Panel viewPanel;

  public TempView()
  {
    myLabel = new Label ( "View" );
    myLabel.setText ( "Current temperature: " );
    myLabel.setForeground ( Color.red );

    viewPanel = new Panel();
    viewPanel.setLayout ( new GridLayout(2,1) );
    viewPanel.add ( new Label ( "View" ) );
    viewPanel.add ( myLabel );
  }

  public Panel getPanel() { return viewPanel; }

  public void update ( Observable ob, Object arg )
  {
    TempModel temp = (TempModel) ob;

    myLabel.setText ( "Temperature: "+temp.F()+"F,   "+
		      temp.C()+"C,   "+temp.K()+"K");
  }
}


class TempController
{
  final private Button myButton;
  final private Panel  myPanel;

  public Panel getPanel() { return myPanel; }

  private TempModel tempModel;

  public TempController ( TempModel toObserve )
  {
    this.tempModel = toObserve;

    myButton = new Button();
    myButton.setForeground ( Color.blue );
    myButton.setLabel ( "Switch temperature (0-"+tempModel.MAX_TEMP_F+"F)" );

    myPanel = new Panel();
    myPanel.setLayout ( new GridLayout(2,1) );
    myPanel.add ( new Label("Controller") );
    myPanel.add ( myButton );

    myButton.addActionListener
      ( new ActionListener()
	{
	  public void actionPerformed (ActionEvent e)
	    {
	      tempModel.setTemperature
		((int)(Math.random()*tempModel.MAX_TEMP_F) );
	    }
	}
      );
  }
}