/**
 * @version 1.20 27 Jun 1998, DB 11/2004
 * @author DB, d'après Cay Horstmann
 */
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class CalculatorPanel extends JPanel implements ActionListener
{  
  public CalculatorPanel()
  {
    setLayout( new BorderLayout( 2, 2 ) );

    display = new TextField( "0" );
    display.setEditable( false );
    display.setBackground( Color.white );
    add( display, "North" );
      
    Panel p = new Panel();
    p.setBackground( Color.yellow );
    p.setLayout( new GridLayout( 5, 4, 3, 3 ) );

    String buttons = "789/456*123-0.^+";
    for ( int i = 0; i < buttons.length(); i++ ) 
      addButton( p, buttons.substring( i, i + 1 ) );

    p.add( boutonEntr );
	boutonEntr.addActionListener(
	  new ActionListener()
	  {
		public void actionPerformed( ActionEvent evt )
		{
		  boutonEntrActionPerformed( evt );
		}
      }
    );

	p.add( boutonEgal );
	boutonEgal.addActionListener(
	  new ActionListener()
	  {
		public void actionPerformed( ActionEvent evt )
		{
		  boutonEgalActionPerformed( evt );
		}
      }
    );

	p.add( boutonClr );
	boutonClr.addActionListener(
	  new ActionListener()
	  {
		public void actionPerformed( ActionEvent evt )
		{
		  boutonClrActionPerformed( evt );
		}
      }
    );

	p.add( boutonMem );
	boutonMem.addActionListener(
	  new ActionListener()
	  {
		public void actionPerformed( ActionEvent evt )
		{
		  boutonMemActionPerformed( evt );
		}
      }
    );

    add( p, "Center" );
    setPreferredSize( new Dimension( 200, 200) );
  } // CalculatorPanel()

  private void addButton( Container c, String s )
  {
     Button b = new Button(s);
     c.add(b);
     b.addActionListener(this);
  } // addButton()
   
  public void actionPerformed( ActionEvent evt )
  {
    String s = evt.getActionCommand();
    if ( '0' <= s.charAt(0) && s.charAt(0) <= '9' || s.equals(".") )
    {
      if (start)  display.setText( s );
      else display.setText( display.getText() + s );
      start = false;
    }
    else if (ok==false)
    {
      op = s.charAt(0);
      ok = true;
    }
  } // actionPerformed()

  private void boutonEntrActionPerformed( ActionEvent evt )
  {
	  if (ok1==false)
	  {
	    op1 = Double.parseDouble( display.getText() );
	    ok1 = true;
	  }
	  else if (ok2==false)
	  {
	    op2 = Double.parseDouble( display.getText() );
	    ok2 = true;
	  }
	  else display.setText( "déjà 2 nombres" );
	  start = true;
  }

  private void boutonEgalActionPerformed( ActionEvent evt )
  {
    if (ok1 && ok && ok2 )
    {
      String s = calculate();
	  displayText( s );
	  try
	  {
	    res = Double.parseDouble( s.substring( 1 + s.indexOf( "=" ) ) );
	  }
	  catch( Exception E )
	  {
	    System.out.println( "Format de sortie de calc() non respecté !" );
	  } // catch
	} // if
  }
   
  private void displayText( String s )
  {
    display.setText( s );
  } // displayText()
   
  private String calculate()
  {
    return MiniCalc.calc( op1, op2, op );
  } // calculate()

  private void boutonClrActionPerformed( ActionEvent evt )
  {
	  displayText( "0" );
	  op1=0; op2=0; op=' ';
	  ok1=false; ok2=false; ok=false; start=true;
  }

  private void boutonMemActionPerformed( ActionEvent evt )
  {
	  displayText( "0" );
	  op1=res; op2=0; op=' ';
	  ok1=true; ok2=false; ok=false; start=true;
  }

// Attributs
  private double  op1, res,  op2;  char op;
  private boolean ok1=false, ok2=false, ok=false;
  
  private Button boutonEntr = new Button("Entr");
  private Button boutonEgal = new Button("=");
  private Button boutonClr  = new Button("C");
  private Button boutonMem  = new Button("M");

  private TextField display;
  private double arg = 0;
  private boolean start = true;
}