/*
 * [PowCost.java]
 *
 * Summary: Calculates the cost of various activities that consume electricity.
 *
 * Copyright: (c) 2010-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.0 2010-12-04 initial version.
 *  1.1 2010-12-06 add duty cycle.
 *  1.2 2010-12-23 fix integer overflow bug for large consumption.
 *  1.3 2011-05-19 tweak the layout. Add more energy-using items.
 *  1.4 2013-01-19 add more items, sort by total cost, fix bug that was chopping a 0, polish alignments.
 *  1.5 2014-06-01 correct bug displaying duration, add cell phone and ipad.
 */
package com.mindprod.powcost;

import com.mindprod.common18.Build;
import com.mindprod.common18.CMPAboutJBox;
import com.mindprod.common18.EIO;
import com.mindprod.common18.FontFactory;
import com.mindprod.common18.HybridJ;
import com.mindprod.common18.Laf;
import com.mindprod.common18.Misc;
import com.mindprod.common18.VersionCheck;
import com.mindprod.currcon.Exch;

import javax.swing.ImageIcon;
import javax.swing.JApplet;
import javax.swing.JComboBox;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JTextField;
import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.io.ObjectInputStream;
import java.text.DecimalFormat;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Locale;
import java.util.Vector;

import static java.lang.System.*;

/**
 * Calculates the cost of various activities that consume electricity.
 * <p/>
 * This is both an Applet and a standalone application.
 * <p/>
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.5 2014-06-01 correct bug displaying duration, add cell phone and ipad.
 * @noinspection FieldCanBeLocal
 * @since 2010-12-02
 */
public final class PowCost extends JApplet
    {
    /**
     * true if you want debugging output
     */
    private static final boolean DEBUGGING = false;

    /**
     * height of Applet in pixels. Does not include bar at top, but does include menu bar.
     */
    private static final int APPLET_HEIGHT = 395;

    /**
     * Width of Applet in pixels.
     */
    private static final int APPLET_WIDTH = 790;

    /**
     * when this app was first copyrighted
     */
    private static final int FIRST_COPYRIGHT_YEAR = 2010;

    /**
     * undisplayed copyright notice
     *
     * @noinspection UnusedDeclaration
     */
    private static final String EMBEDDED_COPYRIGHT =
            "Copyright: (c) 2010-2017 Roedy Green, Canadian Mind Products, http://mindprod.com";

    /**
     * Activity user sees initially
     */
    private static final String INITIAL_ACTIVITY = "run a 1 kw appliance for an hour (i.e. 1 kwh)";

    /**
     * Location user sees initially
     */
    private static final String INITIAL_LOCATION = "ca BC British Columbia";

    /**
     * date this version released.
     */
    private static final String RELEASE_DATE = "2014-06-01";

    /**
     * Title of the Applet
     */
    private static final String TITLE_STRING = "Electric Power Cost Calculator";

    /**
     * Version of the Applet
     */
    private static final String VERSION_STRING = "1.5";

    /**
     * background colour, pale green to match website
     */
    private static final Color BACKGROUND_FOR_BODY = Build.BACKGROUND_FOR_BLENDING;

    /**
     * background where for data entry where user enters a value.
     */
    private static final Color BACKGROUND_FOR_EDITABLE = Color.WHITE;

    /**
     * background colour for instructions.  Default grey is too dark
     */
    private static final Color BACKGROUND_FOR_INSTRUCTIONS = new Color( 0xf8f8f8 );

    /**
     * background colour for labels
     */
    private static final Color BACKGROUND_FOR_LABEL = Build.BACKGROUND_FOR_BLENDING;

    /**
     * darker green resultColor background, don't enter data here.
     */
    private static final Color BACKGROUND_FOR_RESULT_DARK = new Color( 0xa8ffef );

    /**
     * medium green resultColor background, don't enter data here.
     */
    private static final Color BACKGROUND_FOR_RESULT_MEDIUM = new Color( 0xc4ffef );

    /**
     * don't enter data here. raw data.
     */
    private static final Color BACKGROUND_FOR_RESULT_PALE = new Color( 0xe4ffef );

    /**
     * data entry text field colour
     */
    private static final Color FOREGROUND_FOR_EDITABLE = Color.BLACK;

    /**
     * instruction normal color
     */
    private static final Color FOREGROUND_FOR_INSTRUCTIONS = new Color( 0x339911 );

    /**
     * foreground colour for label
     */
    private static final Color FOREGROUND_FOR_LABEL = Color.BLUE;

    /**
     * don't enter data here foreground
     */
    private static final Color FOREGROUND_FOR_RESULT_DARK = Color.BLACK;

    /**
     * /**
     * don't enter data here foreground
     */
    private static final Color FOREGROUND_FOR_RESULT_MEDIUM = Color.BLACK;

    /**
     * don't enter data here. raw data.
     */
    private static final Color FOREGROUND_FOR_RESULT_PALE = new Color( 0x226622 );

    /**
     * for titles
     */
    private static final Color FOREGROUND_FOR_TITLE = new Color( 0xdc143c );

    /**
     * helps format the amount display , for 0 to 4 decimal places DecimalFormat is not thread Safe. That should not
     * matter since all Applets run on the same thread, but just in case... Actual display is Locale dependent, e.g.
     * comma or decimal point.
     */
    private static final DecimalFormat[] df = {
            new DecimalFormat( "###,##0" ) /* 0 */,
            new DecimalFormat( "###,##0.0" ) /* 1 */,
            new DecimalFormat( "###,##0.00" ) /* 2 */,
            new DecimalFormat( "###,##0.000" ) /* 3 */,
            new DecimalFormat( "###,##0.0000" ) /* 4 */,
            new DecimalFormat( "###,##0.00000" ) /* 5 */,
            new DecimalFormat( "###,##0.000000" ) /* 6 */ };

    /**
     * instructions font
     */
    private static final Font FONT_FOR_INSTRUCTIONS = FontFactory.build( "Dialog", Font.PLAIN, 12 );

    /**
     * label font
     */
    private static final Font FONT_FOR_LABEL = FontFactory.build( "Dialog", Font.PLAIN, 13 );

    /**
     * label font
     */
    private static final Font FONT_FOR_LABEL_BOLD = FontFactory.build( "Dialog", Font.BOLD, 14 );

    /**
     * label font
     */
    private static final Font FONT_FOR_LABEL_UNITS = FontFactory.build( "Dialog", Font.PLAIN, 11 );

    /**
     * title font
     */
    private static final Font FONT_FOR_TITLE = FontFactory.build( "Dialog", Font.BOLD, 15 );

    /**
     * for for title second line
     */
    private static final Font FONT_FOR_TITLE2 = FontFactory.build( "Dialog", Font.PLAIN, 14 );

    /**
     * Reddy Kilowatt icon
     */
    private static final ImageIcon LOGO_ICON = new ImageIcon( PowCost.class.getResource( "image/reddy.png" ) );

    /**
     * conversion constant Megajoules per kwh,(1 gallon gasoline =  130 mj)
     */
    private static final double MJ_PER_KWH = 3.6;

    /**
     * Lets us look up 3-letter currency code given 2-letter country code. Final, but compiler does not know that
     */
    private static HashMap<String, String> countryToCurr;

    /**
     * list of objects that describe a country, its currency and exchange rate.
     */
    private static Exch[] exchs;

    static
        {
        // should happen once, only one and before any init method runs.
        fetchCurrencyInfo();
        }

    /**
     * contentPane for the whole Applet
     */
    private Container contentPane;

    /**
     * index Exch record about this currency and its current exchang rate.
     */
    private Exch userExch;

    /* select an electricity-using activity */
    private JComboBox<ActivityItem> activity;

    /**
     * select the cost by selecting the location
     */
    private JComboBox<CostLocItem> location;

    /**
     * "activity" label
     */
    private JLabel activityLabel;

    /**
     * "cost" label
     */
    private JLabel costLabel;

    /**
     * "duration" label
     */
    private JLabel durationLabel;

    /**
     * "dutyCycle" label
     */
    private JLabel dutyCycleLabel;

    /**
     * "energy" label
     */
    private JLabel energyLabel;

    /**
     * "kwh" label
     */
    private JLabel kwhLabel;

    /**
     * "location" label
     */
    private JLabel locationLabel;

    /**
     * Reddy Kilowatt logo
     */
    private JLabel logo; // will have a setIcon

    /**
     * "megajoules" label
     */
    private JLabel megajoulesLabel;

    /**
     * "power" label
     */
    private JLabel powerLabel;

    /**
     * name of app
     */
    private JLabel title;

    /**
     * build and version
     */
    private JLabel title2;

    /**
     * "watts" label
     */
    private JLabel wattsLabel;

    /**
     * where cost result displayed
     */
    private JTextField cost;

    /**
     * display duration of the activity
     */
    private JTextField duration;

    /**
     * display duty cycle in %
     */
    private JTextField dutyCycle;

    /**
     * display instructions for use
     */
    private JTextField instructions;

    /**
     * display energy consumed in kwh
     */
    private JTextField kwh;

    /**
     * display energy consumed  kwh
     */
    private JTextField megajoules;

    /**
     * display power in watts
     */
    private JTextField watts;

    /**
     * code for the user's currency e.g.USD CAD
     */
    private String userCurrAbbr;

    /**
     * read the resource containing country->currency and exchange rates
     */
    private static void fetchCurrencyInfo()
        {
        try
            {
            // O P E N
            // get resources "/com/mindprod/currcon/exchs.ser"
            final ObjectInputStream ois = EIO.getObjectInputStream( PowCost.class.getResourceAsStream( "exchs.ser" ), 4 * 1024, true );
            // R E A D
            long wasResourceVersion = ( Long ) ois.readObject();
            if ( wasResourceVersion != Exch.getSerialVersionUID() )
                {
                throw new IllegalArgumentException( "Wrong version of exchs.ser file.  Was:" + wasResourceVersion +
                                                    " wanted:" + Exch.getSerialVersionUID() );
                }
            // consistency with Geom is not required.
            final String[] country = ( String[] ) ois.readObject();
            final String[] currency = ( String[] ) ois.readObject();
            exchs = ( Exch[] ) ois.readObject();
            // C L O S E
            ois.close();
            countryToCurr = new HashMap<>( 250 * 130 / 100 );
            for ( int i = 0; i < country.length; i++ )
                {
                countryToCurr.put( country[ i ], currency[ i ] );
                }
            }
        catch ( Exception e )
            {
            err.println( "Missing or damaged exchs.ser " + e + "\n" );
            }
        }

    /**
     * Find a given currency abbreviation in the list and return the index of it.
     *
     * @param currAbbr 3-letter ISO code for currency
     *
     * @return corresponding Exch record or null if not found.
     */
    private static Exch findExchangeInfoForCurrency( String currAbbr )
        {
        assert currAbbr != null && currAbbr.length() == 3 : "malformed currency Abbreviation:" + currAbbr;
        /* search for currAbbr in list of currencies */
        for ( Exch exch : exchs )
            {
            if ( exch.getCurrAbbr().equals( currAbbr ) )
                {
                return exch;
                }
            }
        /* did not find it */
        return null;
        }

    /**
     * build all the Swing components.
     */
    private void buildComponents()
        {
        contentPane.setBackground( BACKGROUND_FOR_BODY );
        title = new JLabel( TITLE_STRING + " " + VERSION_STRING, JLabel.LEFT );
        title.setFont( FONT_FOR_TITLE );
        title.setForeground( FOREGROUND_FOR_TITLE );
        title2 = new JLabel(
                "released:" +
                RELEASE_DATE +
                " build:" +
                Build.BUILD_NUMBER, JLabel.LEFT
        );
        title2.setFont( FONT_FOR_TITLE2 );
        title2.setForeground( FOREGROUND_FOR_TITLE );
        activityLabel = new JLabel( "Activity (sorted by cost)" );
        activityLabel.setBackground( BACKGROUND_FOR_LABEL );
        activityLabel.setFont( FONT_FOR_LABEL_BOLD );
        activityLabel.setForeground( FOREGROUND_FOR_LABEL );
        costLabel = new JLabel( "C o s t" );
        costLabel.setBackground( BACKGROUND_FOR_LABEL );
        costLabel.setFont( FONT_FOR_LABEL_BOLD );
        costLabel.setForeground( FOREGROUND_FOR_LABEL );
        durationLabel = new JLabel( "duration" );
        durationLabel.setBackground( BACKGROUND_FOR_LABEL );
        durationLabel.setFont( FONT_FOR_LABEL );
        durationLabel.setForeground( FOREGROUND_FOR_LABEL );
        dutyCycleLabel = new JLabel( "duty cycle" );
        dutyCycleLabel.setBackground( BACKGROUND_FOR_LABEL );
        dutyCycleLabel.setFont( FONT_FOR_LABEL );
        dutyCycleLabel.setForeground( FOREGROUND_FOR_LABEL );
        energyLabel = new JLabel( "energy" );
        activityLabel.setBackground( BACKGROUND_FOR_LABEL );
        energyLabel.setFont( FONT_FOR_LABEL );
        energyLabel.setForeground( FOREGROUND_FOR_LABEL );
        megajoulesLabel = new JLabel( "megajoules" );
        megajoulesLabel.setBackground( BACKGROUND_FOR_LABEL );
        megajoulesLabel.setFont( FONT_FOR_LABEL_UNITS );
        megajoulesLabel.setForeground( FOREGROUND_FOR_LABEL );
        kwhLabel = new JLabel( "kwh" );
        kwhLabel.setBackground( BACKGROUND_FOR_LABEL );
        kwhLabel.setFont( FONT_FOR_LABEL_UNITS );
        kwhLabel.setForeground( FOREGROUND_FOR_LABEL );
        locationLabel = new JLabel( "Location", JLabel.LEFT );
        locationLabel.setBackground( BACKGROUND_FOR_LABEL );
        locationLabel.setFont( FONT_FOR_LABEL_BOLD );
        locationLabel.setForeground( FOREGROUND_FOR_LABEL );
        logo = new JLabel( "" );
        logo.setIcon( LOGO_ICON );
        powerLabel = new JLabel( "power" );
        powerLabel.setBackground( BACKGROUND_FOR_LABEL );
        powerLabel.setFont( FONT_FOR_LABEL );
        powerLabel.setForeground( FOREGROUND_FOR_LABEL );
        wattsLabel = new JLabel( "watts" );
        wattsLabel.setBackground( BACKGROUND_FOR_LABEL );
        wattsLabel.setFont( FONT_FOR_LABEL_UNITS );
        wattsLabel.setForeground( FOREGROUND_FOR_LABEL );
        ActivityItem[] activities = null;
        try
            {
            // O P E N
            // get resources "/com/mindprod/powcost/activities.ser"
            // look in jar, on classpath, locally or server as appropriate, will
            // have package name prepended
            final ObjectInputStream ois = EIO.getObjectInputStream( PowCost.class.getResourceAsStream( "activities.ser" ), 4 * 1024, true );
            // R E A D
            activities = ( ActivityItem[] ) ois.readObject();
            // C L O S E
            ois.close();
            }
        catch ( Exception e )
            {
            err.println( "Missing activities.ser " + e + "\n" );
            }
        // must be Vector, not ArrayList.  JComboBox is legacy.
        activity = new JComboBox<>( new Vector<>( Arrays.asList( activities ) ) );
        activity.setBackground( BACKGROUND_FOR_EDITABLE );
        activity.setEditable( true );
        activity.setFocusable( true );
        activity.setForeground( FOREGROUND_FOR_EDITABLE );
        activity.setMaximumSize( activity.getPreferredSize() );
        assert activities != null;
        for ( int i = 0; i < activities.length; i++ )
            {
            if ( activities[ i ].toString().equals( INITIAL_ACTIVITY ) )
                {
                activity.setSelectedIndex( i );
                break;
                }
            }
        activity.setToolTipText( "Select an activity to find out its cost in your region." );
        cost = new JTextField( 20 );
        cost.setBackground( BACKGROUND_FOR_RESULT_DARK );
        cost.setEditable( false );
        cost.setFocusable( false );
        cost.setForeground( FOREGROUND_FOR_RESULT_DARK );
        cost.setHorizontalAlignment( JTextField.RIGHT );
        duration = new JTextField( 20 );
        duration.setBackground( BACKGROUND_FOR_RESULT_PALE );
        duration.setEditable( false );
        duration.setFocusable( false );
        duration.setForeground( FOREGROUND_FOR_RESULT_PALE );
        duration.setHorizontalAlignment( JTextField.RIGHT );
        dutyCycle = new JTextField( 20 );
        dutyCycle.setBackground( BACKGROUND_FOR_RESULT_PALE );
        dutyCycle.setEditable( false );
        dutyCycle.setFocusable( false );
        dutyCycle.setForeground( FOREGROUND_FOR_RESULT_PALE );
        dutyCycle.setHorizontalAlignment( JTextField.RIGHT );
        megajoules = new JTextField( 20 );
        megajoules.setBackground( BACKGROUND_FOR_RESULT_MEDIUM );
        megajoules.setEditable( false );
        megajoules.setFocusable( false );
        megajoules.setForeground( FOREGROUND_FOR_RESULT_MEDIUM );
        megajoules.setHorizontalAlignment( JTextField.RIGHT );
        kwh = new JTextField( 20 );
        kwh.setBackground( BACKGROUND_FOR_RESULT_MEDIUM );
        kwh.setEditable( false );
        kwh.setFocusable( false );
        kwh.setForeground( FOREGROUND_FOR_RESULT_MEDIUM );
        kwh.setHorizontalAlignment( JTextField.RIGHT );
        CostLocItem[] costs = null;
        try
            {
            // O P E N
            // get resources "/com/mindprod/powcost/costs.ser"
            // look in jar, on classpath, locally or server as appropriate, will
            // have package name prepended
            final ObjectInputStream ois = EIO.getObjectInputStream( PowCost.class.getResourceAsStream( "costs.ser" ), 4 * 1024, true );
            // R E A D
            costs = ( CostLocItem[] ) ois.readObject();
            // C L O S E
            ois.close();
            }
        catch ( Exception e )
            {
            err.println( "Missing costs.ser " + e + "\n" );
            }
        // must be Vector, not ArrayList.  JComboBox is legacy.
        location = new JComboBox<>( new Vector<>( Arrays.asList( costs ) ) );
        location.setBackground( BACKGROUND_FOR_EDITABLE );
        location.setEditable( true );
        location.setFocusable( true );
        location.setForeground( FOREGROUND_FOR_EDITABLE );
        location.setMaximumSize( location.getPreferredSize() );
        assert costs != null;
        for ( int i = 0; i < costs.length; i++ )
            {
            if ( costs[ i ].toString().equals( INITIAL_LOCATION ) )
                {
                location.setSelectedIndex( i );
                break;
                }
            }
        location.setToolTipText( "Select your location since electricity prices vary wildly by region." );
        watts = new JTextField( 20 );
        watts.setBackground( BACKGROUND_FOR_RESULT_PALE );
        watts.setEditable( false );
        watts.setFocusable( false );
        watts.setForeground( FOREGROUND_FOR_RESULT_PALE );
        watts.setHorizontalAlignment( JTextField.RIGHT );
        instructions = new JTextField(
                "Select a location, then an electricity-using activity to find out how much that activity will cost " +
                "in your local currency."
        );
        instructions.setBackground( BACKGROUND_FOR_INSTRUCTIONS );
        instructions.setEditable( false );
        instructions.setFocusable( false );
        instructions.setFont( FONT_FOR_INSTRUCTIONS );
        instructions.setForeground( FOREGROUND_FOR_INSTRUCTIONS );
        instructions.setMargin( new Insets( 2, 2, 2, 2 ) );
        }

    /**
     * build a menu with Look & Feel and About across the top
     */
    private void buildMenu()
        {
        // turn on anti-alias
        System.setProperty( "swing.aatext", "true" );
        final JMenuBar menubar = new JMenuBar();
        setJMenuBar( menubar );
        final JMenu lafMenu = Laf.buildLookAndFeelMenu();
        if ( lafMenu != null )
            {
            menubar.add( lafMenu );
            }
        final JMenu menuHelp = new JMenu( "Help" );
        menubar.add( menuHelp );
        final JMenuItem aboutItem = new JMenuItem( "About" );
        menuHelp.add( aboutItem );
        aboutItem.addActionListener( new ActionListener()
            {
            public void actionPerformed( ActionEvent e )
                {
                // open about frame
                new CMPAboutJBox( Misc.getParentFrame( PowCost.this ),
                        TITLE_STRING,
                        VERSION_STRING,
                        "Calculates cost of electric watts for various activities",
                        "",
                        "freeware",
                        RELEASE_DATE,
                        FIRST_COPYRIGHT_YEAR,
                        "Roedy Green",
                        "POWCOST",
                        "1.8" );
                }
            } );
        }

    /**
     * when user selects different options, recompute the cost.
     */
    private void calcCost()
        {
        /* get selected info from the selected activity and cost/location */
        final ActivityItem activityChoice = ( ActivityItem ) activity.getSelectedItem();
        final double powerInWatts = activityChoice.getWatts();
        final double dutyCycleInPercent = activityChoice.getDutyCycle();
        final double seconds = activityChoice.getSeconds();
        final CostLocItem costChoice = ( CostLocItem ) location.getSelectedItem();
        final String currencyAbbrForLocation = costChoice.getCurrencyAbbr();
        final Exch locationExch = findExchangeInfoForCurrency( currencyAbbrForLocation );
        if ( locationExch == null )
            {
            throw new IllegalArgumentException( "No exchange rate defined for " + currencyAbbrForLocation );
            }
        int decimalPlaces = userExch.getDecimalPlaces();
        // In Swing we can render pretty well any symbol, so we don't meddle with it as we do in CurrCon
        final String currencySymbol = userExch.getSymbol();
        final double costPerKwh = costChoice.getCostPerKwh();
        /* calculate */
        final double energyInKwh = ( powerInWatts * seconds * dutyCycleInPercent ) /
                                   ( double ) ( 60 * 60 * 1000 * 100 );
        // div 1000 convert watts to kwatts
        // div 60 * 60 convert seconds to hours.
        // div 100 to convert percent to ratio
        // the more the location currency is worth, the higher the cost.
        // the lower the users currency is worth, the higher the cost.
        double exchangeAdjust = locationExch.getExchangeRate() / userExch.getExchangeRate();
        final double costOfActivity = energyInKwh * costPerKwh * exchangeAdjust;
        final double energyInMJ = energyInKwh * MJ_PER_KWH;
        if ( DEBUGGING )
            {
            out.println( "powerInWatts:"
                         + powerInWatts
                         + " dutyCycle:"
                         + dutyCycleInPercent
                         + " costPerKwh:"
                         + costPerKwh
                         + " seconds:"
                         + seconds
                         + " energyInKwh:"
                         + energyInKwh
                         + " costPerKwh:"
                         + costPerKwh
                         + " exchangeAdjust:"
                         + exchangeAdjust
                         + " costOfActivity:"
                         + costOfActivity );
            }
        /* display calculations */
        watts.setText( df[ powerInWatts < 10 ? 1 : 0 ].format( powerInWatts ) );
        dutyCycle.setText( df[ 0 ].format( dutyCycleInPercent ) + '%' );
        duration.setText( activityChoice.getDuration() );
        kwh.setText( df[ 2 ].format( energyInKwh ) );
        megajoules.setText( df[ 2 ].format( energyInMJ ) );
        if ( costOfActivity > 0 )
            {
            // if less than a penny, show an extra decimal place, and analogously for other currencies
            final int decade = ( int ) Math.floor( Math.log10( costOfActivity ) );
            decimalPlaces = Math.min( Math.max( decimalPlaces, -decade ), decimalPlaces + 3 );
            }
        assert ( 0 <= decimalPlaces && decimalPlaces <= 6 ) : "too many decimal places requested. Problem in currency" +
                                                              " configuration file.";
        cost.setText( currencySymbol + df[ decimalPlaces ].format( costOfActivity ) + " " + userCurrAbbr );
        }

    /**
     * guess at user's preferred viewing currency based on his country locale
     * Calculates both userCurrCode and userExch
     */
    private void guessUserCurrency()
        {
        try
            {
            String countryAbbr = Locale.getDefault().getCountry();
            userCurrAbbr = countryToCurr.get( countryAbbr );
            userExch = findExchangeInfoForCurrency( userCurrAbbr );
            }
        catch ( Exception e )
            {
            userExch = null;
            }
        if ( userExch == null )
            {
            /* user in a country for which we have no exchange rate data */
            /* Show him US$ */
            userCurrAbbr = "USD";
            userExch = findExchangeInfoForCurrency( userCurrAbbr );
            }
        }

    /**
     * hook up the listeners
     */
    private void hookListeners()
        {
        location.addItemListener( new ItemListener()
            {
            /**
             * Notice any change to one of the list box selectors.
             * @param e details of just what the user clicked.
             */
            public void itemStateChanged( ItemEvent e )
                {
                calcCost();
                }
            } );
        activity.addItemListener( new ItemListener()
            {
            /**
             * Notice any change to one of the list box selectors.
             * @param e details of just what the user clicked.
             */
            public void itemStateChanged( ItemEvent e )
                {
                calcCost();
                }
            } );
        }

    /**
     * layout fields in GridBag
     */
    private void layoutComponents()
        {
        contentPane.setLayout( new GridBagLayout() );
        // _____ 0________1______2___________3 ________4____5___6___
        // 0  Title----------------    ------title2------- --logo-- 0
        // 1 ~location------           ~activity--------  -- -"---- 1
        // 2  location------           activity-------------------- 2
        // 3  ~duty    ~power          ~duration     ~energy  ~cost 3
        // 4  duty     watts  ~watts   duration      kwh  ~kwh cost 4
        // 5                                          mj  ~mj       5
        // 6  instructions----------------------------------------- 6
        //
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( title,
                new GridBagConstraints( 0,
                        0,
                        3,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 20, 10, 5, 5 ), // top, left, bottom, right
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( title2,
                new GridBagConstraints( 3,
                        0,
                        2,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 20, 5, 5, 5 ), // top, left, bottom, right
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( locationLabel,
                new GridBagConstraints( 0,
                        1,
                        2,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.SOUTHWEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 10, 5, 5 ), // top, left, bottom, right
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( activityLabel,
                new GridBagConstraints( 3,
                        1,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.SOUTHWEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 5, 5, 5 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( logo,
                new GridBagConstraints( 5,
                        0,
                        2,
                        2,
                        0.0,
                        0.0,
                        GridBagConstraints.EAST,
                        GridBagConstraints.NONE,
                        new Insets( 10, 5, 5, 10 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( location,
                new GridBagConstraints( 0,
                        2,
                        2,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 10, 5, 5 ),
                        5,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( activity,
                new GridBagConstraints( 3,
                        2,
                        4,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 5, 5, 10 ),
                        5,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( dutyCycleLabel,
                new GridBagConstraints( 0,
                        3,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.SOUTHEAST,
                        GridBagConstraints.NONE,
                        new Insets( 10, 10, 5, 5 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( powerLabel,
                new GridBagConstraints( 1,
                        3,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.SOUTHEAST,
                        GridBagConstraints.NONE,
                        new Insets( 10, 5, 5, 5 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( durationLabel,
                new GridBagConstraints( 3,
                        3,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.SOUTHEAST,
                        GridBagConstraints.NONE,
                        new Insets( 10, 5, 5, 5 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( energyLabel,
                new GridBagConstraints( 4,
                        3,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.SOUTHEAST,
                        GridBagConstraints.NONE,
                        new Insets( 10, 5, 5, 5 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( costLabel,
                new GridBagConstraints( 6,
                        3,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.EAST,
                        GridBagConstraints.NONE,
                        new Insets( 10, 5, 5, 10 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( dutyCycle,
                new GridBagConstraints( 0,
                        4,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.EAST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 10, 5, 5 ),
                        60,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( watts,
                new GridBagConstraints( 1,
                        4,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.EAST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 5, 5, 2 ),
                        60,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( wattsLabel,
                new GridBagConstraints( 2,
                        4,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 0, 5, 5 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( duration,
                new GridBagConstraints( 3,
                        4,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 5, 5, 5 ),
                        110,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( kwh,
                new GridBagConstraints( 4,
                        4,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 5, 5, 2 ),
                        75,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( kwhLabel,
                new GridBagConstraints( 5,
                        4,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 0, 5, 5 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( cost,
                new GridBagConstraints( 6,
                        4,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.EAST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 5, 5, 10 ),
                        100,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( megajoules,
                new GridBagConstraints( 4,
                        5,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 5, 5, 2 ),
                        75,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( megajoulesLabel,
                new GridBagConstraints( 5,
                        5,
                        1,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.NONE,
                        new Insets( 5, 0, 5, 5 ),
                        0,
                        0 )
        );
        // x y w h wtx wty anchor fill T L B R padx pady
        contentPane.add( instructions,
                new GridBagConstraints( 0,
                        6,
                        7,
                        1,
                        0.0,
                        0.0,
                        GridBagConstraints.WEST,
                        GridBagConstraints.BOTH,
                        new Insets( 5, 10, 10, 10 ),
                        0,
                        0 )
        );
        }

    /**
     * Allow this Applet to run as as application as well.
     *
     * @param args command line arguments ignored.
     */
    public static void main( String args[] )
        {
        HybridJ.fireup( new PowCost(),
                TITLE_STRING + " " + VERSION_STRING,
                APPLET_WIDTH,
                APPLET_HEIGHT );
        } // end main

    /**
     * Called by the browser or Applet viewer to inform
     * this Applet that it is being reclaimed and that it should destroy
     * any resources that it has allocated.
     */
    @Override
    public void destroy()
        {
        activity = null;
        activityLabel = null;
        contentPane = null;
        cost = null;
        costLabel = null;
        duration = null;
        durationLabel = null;
        dutyCycle = null;
        dutyCycleLabel = null;
        energyLabel = null;
        instructions = null;
        kwh = null;
        kwhLabel = null;
        location = null;
        locationLabel = null;
        logo = null;
        megajoules = null;
        megajoulesLabel = null;
        powerLabel = null;
        userExch = null;
        title2 = null;
        title = null;
        userCurrAbbr = null;
        watts = null;
        wattsLabel = null;
        }

    /**
     * Called by the browser or Applet viewer to inform
     * this Applet that it has been loaded into the system.
     */
    @Override
    public void init()
        {
        contentPane = getContentPane();
        if ( !VersionCheck.isJavaVersionOK( 1, 7, 0, contentPane ) )
            {
            // abort
            stop();
            destroy();
            }
        buildMenu(); // also initial L&F
        buildComponents();
        layoutComponents();
        hookListeners();
        guessUserCurrency();
        calcCost();
        this.validate();
        this.setVisible( true );
        }
    }