//********************************************************************
//  GUICalculator.java       Author: Sophie Quigley
//
//  Provides a graphical user interface for the Calculator Class
//
//********************************************************************

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GUICalculator
{
   private static final boolean ONE = true;     // One entry on stack will be cleared
   private static final boolean ALL = false;    // Whole stack should be cleared

   private static final char PLUSLABEL = (char) 0x002B;
   private static final char MINUSLABEL = (char) 0x002D;
   private static final char TIMESLABEL = (char) 0x00D7;
   private static final char DIVLABEL = (char) 0x00F7;
   
   private Calculator calculator;
   private JFrame frame;
   private JPanel panel;
   private JLabel instructions1, instructions2, instructions3;
   private JTextField number;
   private JButton clearone, clearall;
   private JButton[] operation;
   private Character[] oplabel = {new Character(PLUSLABEL),new Character(MINUSLABEL),
        new Character(TIMESLABEL),new Character(DIVLABEL)};
   
   public GUICalculator ()
   {
      int i;
      
      calculator = new Calculator();
      calculator.addViewer(Calculator.GRAPHICSVIEWER);
      
      frame = new JFrame("Reverse Polish Notation Calculator");
      frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

      // Create labels, buttons and text field
      instructions1 = new JLabel ("Enter a number and press enter");
      instructions2 = new JLabel ("or press an operation button. ");
      instructions3 = new JLabel ("You can also correct your inputs:");
      number = new JTextField (10);
      clearone = new JButton("Clear last entry");
      clearall = new JButton("Clear all entries");
      operation = new JButton[4];
      for (i=0; i<4; i++)
          operation[i] = new JButton(oplabel[i].toString());

      // Add labels buttons and text field to panel.
      panel = new JPanel();
      panel.setPreferredSize (new Dimension(200, 200));
      panel.setBackground (Color.cyan);
      panel.add (instructions1);
      panel.add (number);
      panel.add (instructions2);
      for (i=0; i<4; i++)
        panel.add (operation[i]);
      panel.add (instructions3);
      panel.add (clearone);
      panel.add (clearall);

      frame.getContentPane().add (panel);
      
      // Add event drivers for buttons and text field
      number.addActionListener(new NumberListener());
      clearone.addActionListener(new ClearListener(ONE));
      clearall.addActionListener(new ClearListener(ALL));
      for (i=0; i<4; i++)
          operation[i].addActionListener(new OperationListener(i));
     
      
   }

   //-----------------------------------------------------------------
   //  Displays the primary application frame.
   //-----------------------------------------------------------------
   public void display()
   {
      frame.pack();
      frame.show();
   }
    //*****************************************************************
   //  Action listener for the number input field.
   //*****************************************************************
   private class NumberListener implements ActionListener
   {
      //  Performs action when enter key is pressed in the text field
      public void actionPerformed (ActionEvent event)
      {
         calculator.number(new Float(number.getText()));
         number.setText("");
      }
   }
   // Action listener for the buttons
   private class ClearListener implements ActionListener
   {
       private boolean one;
       public ClearListener (boolean one)
       {
           this.one = one;
       }
       public void actionPerformed (ActionEvent event)
       {
           if (one)
               calculator.eraseLast();
           else
                calculator.clear();
       }
   }
   
   // Action listener for the operation buttons
   private class OperationListener implements ActionListener
   {
       private int opcode;
       public OperationListener(int opcode)
       {
           this.opcode = opcode;
       }
       public void actionPerformed (ActionEvent event)
       {
           number.setText("");
           calculator.operation(opcode);
       }
   }
   
}