/*
   Applet Arithmelet implements a simple GUI calculator, providing three
   LCDs (one for each operand and one for the result of one of 4 operations:
   add, subtract, multiply, and divide.

   There is an non-Applet version called Arithmelator that implements the
   same feature set.

   Program written by Michael Grobe...April 2001.
*/

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

public class Arithmelet extends javax.swing.JApplet implements ActionListener
{
	public static String firstOperandString = new String("");
	public static double firstOperandValue=0;

	public static String secondOperandString = new String("");
	public static double secondOperandValue=0;

	public static String resultString = new String("0");
	public static double result=0;
	public static String resultSaveString = new String("");

	public static String operator = new String("");

	public static JTextField firstOperandLCD = new JTextField(12);
	public static JTextField secondOperandLCD = new JTextField(12);
	public static JTextField resultLCD = new JTextField(12);
	public static Font LCDfont = new Font("Geneva", Font.BOLD, 40);

	public void init()				// set up the GUI here.
	{
		JFrame arithmeletFrame = new JFrame("Arithmelet");

		Container c = arithmeletFrame.getContentPane();  // replace this line with
		//Container c = this.getContentPane();           // this line to display applet
														 // within the html page.
		c.setLayout(new BorderLayout(10,10));
		arithmeletFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);   // remove this line to display in page.

		JPanel operands = new JPanel();
		TitledBorder operandsBorder = new TitledBorder("Enter operands here");
		operandsBorder.setTitlePosition(TitledBorder.TOP);
		operandsBorder.setTitleJustification(TitledBorder.LEFT);

		operands.setBorder(operandsBorder);
		operands.setLayout(new GridLayout(3,1));

		firstOperandLCD.setFont(LCDfont);
		firstOperandLCD.setEditable(true);
		firstOperandLCD.setText(firstOperandString);

		operands.add(firstOperandLCD);

		JPanel opkeys = new JPanel();
		TitledBorder opkeyBorder = new TitledBorder("Choose an operator");
		opkeyBorder.setTitlePosition(TitledBorder.TOP);
		opkeyBorder.setTitleJustification(TitledBorder.LEFT);
		opkeys.setBorder(opkeyBorder);

		Font opkeyfont = new Font("Geneva", Font.BOLD, 40);
		opkeys.setLayout(new GridLayout(1,5,0,0) );

		JButton butplus = new JButton("+");
		butplus.setActionCommand("plus");
		butplus.addActionListener(this);
		butplus.setFont(opkeyfont);

		JButton butminus= new JButton("-");
		butminus.setActionCommand("minus");
		butminus.addActionListener(this);
		butminus.setFont(opkeyfont);

		JButton butmultiply = new JButton("*");
		butmultiply.setActionCommand("multiply");
		butmultiply.addActionListener(this);
		butmultiply.setFont(opkeyfont);

		JButton butdivide = new JButton("/");
		butdivide.setActionCommand("divide");
		butdivide.addActionListener(this);
		butdivide.setFont(opkeyfont);

		opkeys.add(butplus);
		opkeys.add(butminus);
		opkeys.add(butmultiply);
		opkeys.add(butdivide);

		operands.add(opkeys);

		secondOperandLCD.setFont(LCDfont);
		secondOperandLCD.setEditable(true);
		secondOperandLCD.setText(secondOperandString);

		operands.add(secondOperandLCD);

		JPanel assignkeys = new JPanel();
		TitledBorder assignkeyBorder = new TitledBorder("Move the result or calculate");
		assignkeyBorder.setTitlePosition(TitledBorder.TOP);
		assignkeyBorder.setTitleJustification(TitledBorder.LEFT);
		assignkeys.setBorder(assignkeyBorder);

		Font assignkeyfont = new Font("Geneva", Font.BOLD, 40);
		assignkeys.setLayout(new GridLayout(1,3,0,0) );

		JButton butequal = new JButton("=");
		butequal.setActionCommand("equal");
		butequal.addActionListener(this);
		butequal.setFont(assignkeyfont);

		JButton butshift = new JButton("shift");
		butshift.setActionCommand("shift");
		butshift.addActionListener(this);
		butshift.setFont(assignkeyfont);

		assignkeys.add(butshift);
		assignkeys.add(butequal);

		//operands.add(assignkeys);

		c.add(operands, "North");
		c.add(assignkeys, "Center");

		JPanel result = new JPanel();
		TitledBorder resultBorder = new TitledBorder("Here is the result");
		resultBorder.setTitlePosition(TitledBorder.TOP);
		resultBorder.setTitleJustification(TitledBorder.LEFT);
		result.setBorder(resultBorder);

		result.setLayout(new GridLayout(1,1,5,10) );

		resultLCD.setFont(LCDfont);
		resultLCD.setEditable(true);
		resultLCD.setText(resultString);

		result.add(resultLCD);

		c.add(result, "South");

		arithmeletFrame.setBounds(100,100,330,500);  // replace this line with
		//this.setBounds(100,100,330,500);           // this line to stay in page.
		arithmeletFrame.setVisible(true);     // replace this line with
		//this.setVisible(true);              // this line to stay in page.
	}

	public Arithmelet()
	{

	}

	public double ConverttoDouble(String astring) throws NumberFormatException
	{
		double quack;
		System.out.println("Converting:"+astring);
		try
		{
			quack = Double.parseDouble(astring);
		}
		catch ( NumberFormatException exception1)
		{
			System.out.println("Processing exception.");
			quack = 0.0d;
		}
		return quack;
	}

	public String ConverttoNaN(String astring) throws NumberFormatException
	{
		double quack;
		System.out.println("Converting:"+astring);
		try
		{
			quack = Double.parseDouble(astring);
		}
		catch ( NumberFormatException exception1)
		{
			System.out.println("Processing exception.");
			return "NaN";
		}
		return astring;
	}

	public void actionPerformed(ActionEvent event)   // Process GUI input here.
	{
		String command = event.getActionCommand();
		System.out.println("The command (button) pressed was:"+command);

		if ( ( command == "plus" ) || ( command == "multiply" ) ||
			     ( command == "divide" )  || ( command == "minus" ) )
		{
			operator = command;
			System.out.println("Operator="+operator);
		}
		else if ( command == "equal" )
		{
			firstOperandString = firstOperandLCD.getText();
			firstOperandValue = ConverttoDouble( firstOperandString );
			firstOperandString = ConverttoNaN( firstOperandString );
			System.out.println("First op="+firstOperandValue);
			System.out.println("First op string="+firstOperandString);

			secondOperandString = secondOperandLCD.getText();
			secondOperandValue = ConverttoDouble( secondOperandString );
			secondOperandString = ConverttoNaN( secondOperandString );
			System.out.println("Second op="+secondOperandValue);
			System.out.println("Second op string="+secondOperandString);

			if ( firstOperandString.equals("NaN") ||
				 secondOperandString.equals("NaN") )
			{
				resultString = "NaN";
			}
			else if ( operator.equals( "plus" ) )
			{
				result = firstOperandValue + secondOperandValue;
			}
			else if (operator.equals( "minus" ) )
			{
				result = firstOperandValue - secondOperandValue;
			}
			else if (operator.equals( "multiply" ) )
			{
				result = firstOperandValue * secondOperandValue;
				}
			else if (operator.equals( "divide" ) )
			{
				if ( 1 == 1 )  //secondOperandValue != 0.0d )
				{
					result = firstOperandValue / secondOperandValue;
				}
				else
				{
					result = 0.0d;		// this should be epsilon compare!
					resultString = "NaN";
				}
			}
			else
			{
				System.out.println( "No operator specified." );
				resultString = "No operator specified.";
			}

			System.out.println ("Result is:"+result);
			if ( ! resultString.equals ("NaN") &&
				 ! resultString.equals ("No operator specified.") )
			{
				resultString = Double.toString(result);
			}

			int fieldwidth = resultLCD.getSize().width;
			int fontsize = (int) (1.9 * (fieldwidth / (resultString.length() + 1)));
			if (fontsize >40 )
			{
				fontsize = 40;
			}
			// Adjust LCD text font so that the contents always fit.
			Font LCDadjustablefont = new Font("Geneva", Font.BOLD, fontsize);
			resultLCD.setFont(LCDadjustablefont);
			resultLCD.setText(resultString);
			operator = "";
			resultSaveString = resultString;
			resultString = "";
		}
		else if ( command == "shift" )
		{
			firstOperandValue = result;
			firstOperandString = resultSaveString;
			resultString = "";
			result = 0.0d;

			// Adjust LCD text font so that the contents always fit.
			int fieldwidth = firstOperandLCD.getSize().width;
			int fontsize = (int) (1.9 * (fieldwidth / (firstOperandString.length() + 1)));
			if (fontsize >40 )
			{
				fontsize = 40;
			}
			Font LCDadjustablefont = new Font("Geneva", Font.BOLD, fontsize);
			firstOperandLCD.setFont(LCDadjustablefont);
			firstOperandLCD.setText(firstOperandString);

			fieldwidth = resultLCD.getSize().width;
			fontsize = (int) (1.9 * (fieldwidth / (resultString.length() + 1)));
			if (fontsize >40 )
			{
				fontsize = 40;
			}
			// Adjust LCD text font so that the contents always fit.
			Font LCDadjustablefont2 = new Font("Geneva", Font.BOLD, fontsize);
			resultLCD.setFont(LCDadjustablefont2);
			resultLCD.setText(resultString);
		}
		else
		{
			resultLCD.setText("Operation unknown.");
			System.out.println("Operation unknown.");
			stop();
		}
	}
}