/**
 * Class TempConvert
 *
 *  Write a temperature conversion program that converts
 *  from Fahrenheit to Celsius and back again.  
 *  The Fahrenheit temperature should be entered from the keyboard 
 *  (via a JTextField).  
 *  A JLabel should be used to display the converted temperature.  
 *  Use the following formula for the conversion:
 *          Celsius = 5/9 x ( Fahrenheit -32)
 * 
 * @author Ian Johnson
 * @version 19/04/2007
 */

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

public class TempConvert extends JFrame implements ActionListener
{
    // Content pane and input field
    private JPanel jContentPane = null;
    private JTextField inputTemp = null;
    
   // Choice buttons
    private JButton butCelsius = null;
    private JButton butFahrenheit = null;
    
    // Label for user interaction
    final JLabel inputTxt = new JLabel("Input the temperature to be converted");
    final JLabel outputInTxt = new JLabel("To which temperature scale do you wish to convert?");
    final JLabel tempResult = new JLabel("");
    
    double tempInput;

    // Constructor
    public TempConvert() 
    {    
             initialize();
    }


    // Initialize the JFrame
    private void initialize() 
    {
        this.setSize(305, 250);
        this.setTitle("Temperature Converter");
        this.setLayout(new FlowLayout());

        // Initialise entry screen
        this.add(inputTxt);
        inputTemp = new JTextField(6);
        this.add(inputTemp, null);
        this.add(outputInTxt);
        
        // Set for choice buttons
        butCelsius = new JButton("  Celsius   ");
        butCelsius.addActionListener(this);
        this.add(butCelsius, null);
                                    
        butFahrenheit = new JButton(" Fahrenheit ");
        butFahrenheit.addActionListener(this);
        this.add(butFahrenheit, null);

        // Will use label to display input and results
        this.add(tempResult);
   
    }
    // end method initialize
    

    // Method clearInput -blank the input string for a retry
    public void clearInput()
    {
        inputTemp.setText("");
    }
    // end method clearInput
    
    
    // Method toCelsius -Convert users input to celsius
    private void toCelsius() 
    {
        // Convert  &  message input and result to user
        double inCelsius = (( tempInput -32)*5)/9;
        
        String scaleInfo =  String.format(" %.1f degrees Fahrenheit is \n %.1f degrees Celsius", tempInput, inCelsius );
   
        // Display message as label
        tempResult.setText(scaleInfo);
    }
    // end method toCelsius
 
     
    // Method toFahrenheit -Convert users input to fahrenheit
    private void toFahrenheit() 
    {
        // Convert  &  message input and result to user
        double inFahrenheit = ((tempInput * 9)/5) + 32;
        
        String scaleInfo =  String.format(" %.1f degrees Celsius is %.1f degrees Fahrenheit", tempInput, inFahrenheit );
   
        // Display message as label
        tempResult.setText(scaleInfo);
    }
    // end method toFahrenheit
          
    //Event handler to catch choice 
    public void actionPerformed(java.awt.event.ActionEvent e) 
    {
        boolean dataOK;
        // If entered data ok 
        //   - message user, sort & display end result
        if (e.getSource() == butCelsius || e.getSource() == butFahrenheit)
        {
            // First validate the user has input integers
            dataOK = validateEntry();

           // Convert and message the answer to the user
            if (e.getSource() == butCelsius && dataOK ) 
            toCelsius();
            
            if (e.getSource() == butFahrenheit && dataOK ) 
            toFahrenheit();
             
            // clear the input fields
            if (dataOK)
            clearInput();
        }
    }
    // end Event handler


    // Load tempResult array verifying the user input
    private boolean validateEntry() 
    {
        try 
        {
            tempInput = new Double(inputTemp.getText());
        } 
        // Catch any exception and display error
        catch (Exception e) 
        {
            JOptionPane.showMessageDialog(null, "Error " + e.getMessage(), "Error", JOptionPane.ERROR_MESSAGE); 
            return false;
        }
        return true;
    }
    // end method validateInput
}