/////////////////////////////////////////////////////////////////////////
//
// © University of Southampton IT Innovation Centre, 2004
//
// Copyright in this library belongs to the IT Innovation Centre of
// 2 Venture Road, Chilworth Science Park, Southampton, SO16 7NP, UK.
//
// This software may not be used, sold, licensed, transferred, copied
// or reproduced in whole or in part in any manner or form or in or
// on any media by any person other than in accordance with the terms
// of the Licence Agreement supplied with the software, or otherwise
// without the prior written consent of the copyright owners.
//
// This software is distributed WITHOUT ANY WARRANTY, without even the
// implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
// PURPOSE, except where stated in the Licence Agreement supplied with
// the software.
//
//      Created by:             Stuart E. Middleton
//      Created date:           2004/04/30
//      Created for project:    GEMSS
//
/////////////////////////////////////////////////////////////////////////
//
//      Dependencies: Freely distributed example code from builder.com
//
/////////////////////////////////////////////////////////////////////////
//
//      Last commit info:       $Author: $
//                              $Date: $
//                              $Revision: $
//
/////////////////////////////////////////////////////////////////////////

// Obtained from builder.com, source published free with no licence
package uk.ac.soton.itinnovation.gemss.utils.signalhandlers;

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;



/**
 * Custom dialog box to enter dates. The <code>DateChooser</code>
 * class presents a calendar and allows the user to visually select a
 * day, month and year so that it is impossible to enter an invalid
 * date.
 **/
public class DateChooser extends JDialog 
    implements ItemListener, MouseListener, FocusListener, KeyListener, ActionListener
{
    /** Names of the months. */
    private static final String[] MONTHS = 
	new String[] {
	    "January",
	    "February",
	    "March",
	    "April",
	    "May",
	    "June",
	    "July",
	    "August",
	    "September",
	    "October",
	    "November",
	    "December"
	};

    /** Names of the days of the week. */
    private static final String[] DAYS =
	new String[] {
	    "Sun",
	    "Mon",
	    "Tue",
	    "Wed",
	    "Thu",
	    "Fri",
	    "Sat"
	};

    /** Text color of the days of the weeks, used as column headers in
        the calendar. */
    private static final Color WEEK_DAYS_FOREGROUND = Color.black;

    /** Text color of the days' numbers in the calendar. */
    private static final Color DAYS_FOREGROUND = Color.blue;

    /** Background color of the selected day in the calendar. */
    private static final Color SELECTED_DAY_FOREGROUND = Color.white;

    /** Text color of the selected day in the calendar. */
    private static final Color SELECTED_DAY_BACKGROUND = Color.blue;

    /** Empty border, used when the calendar does not have the focus. */
    private static final Border EMPTY_BORDER = BorderFactory.createEmptyBorder(1,1,1,1);

    /** Border used to highlight the selected day when the calendar
        has the focus. */
    private static final Border FOCUSED_BORDER = BorderFactory.createLineBorder(Color.yellow,1);

    /** First year that can be selected. */
    private static final int FIRST_YEAR = 1900;

    /** Last year that can be selected. */
    private static final int LAST_YEAR = 2100;

    /** Auxiliary variable to compute dates. */
    private GregorianCalendar calendar;

    /** Calendar, as a matrix of labels. The first row represents the
        first week of the month, the second row, the second week, and
        so on. Each column represents a day of the week, the first is
        Sunday, and the last is Saturday. The label's text is the
        number of the corresponding day. */
    private JLabel[][] days;

    /** Day selection control. It is just a panel that can receive the
        focus. The actual user interaction is driven by the
        <code>DateChooser</code> class. */
    private FocusablePanel daysGrid;

    /** Month selection control. */
    private JComboBox month;

    /** Year selection control. */
    private JComboBox year;

    /** "Ok" button. */
    private JButton ok;

    /** "Cancel" button. */
    private JButton cancel;

    /** Day of the week (0=Sunday) corresponding to the first day of
        the selected month. Used to calculate the position, in the
        calendar ({@link #days}), corresponding to a given day. */
    private int offset;

    /** Last day of the selected month. */
    private int lastDay;

    /** Selected day. */
    private JLabel day;

    /** <code>true</code> if the "Ok" button was clicked to close the
        dialog box, <code>false</code> otherwise. */
    private boolean okClicked;



    /**
     * Custom panel that can receive the focus. Used to implement the
     * calendar control.
     **/
    private static class FocusablePanel extends JPanel
    {
	/**
	 * Constructs a new <code>FocusablePanel</code> with the given
	 * layout manager.
	 *
	 * @param layout layout manager
	 **/
	public FocusablePanel( LayoutManager layout ) {
	    super( layout );
	}


	/**
	 * Always returns <code>true</code>, since
	 * <code>FocusablePanel</code> can receive the focus.
	 *
	 * @return <code>true</code>
	 **/
	public boolean isFocusTraversable() {
	    return true;
	}
    }



    /**
     * Initializes this <code>DateChooser</code> object. Creates the
     * controls, registers listeners and initializes the dialog box.
     **/
    private void construct()
    {
	calendar = new GregorianCalendar();

	month = new JComboBox(MONTHS);
	month.addItemListener( this );

	year = new JComboBox();
	for ( int i=FIRST_YEAR; i<=LAST_YEAR; i++ )
	    year.addItem( Integer.toString(i) );
	year.addItemListener( this );

	days = new JLabel[7][7];
	for ( int i=0; i<7; i++ ) {
	    days[0][i] = new JLabel(DAYS[i],JLabel.RIGHT);
	    days[0][i].setForeground( WEEK_DAYS_FOREGROUND );
	}
	for ( int i=1; i<7; i++ )
	    for ( int j=0; j<7; j++ )
		{
		    days[i][j] = new JLabel(" ",JLabel.RIGHT);
		    days[i][j].setForeground( DAYS_FOREGROUND );
		    days[i][j].setBackground( SELECTED_DAY_BACKGROUND );
		    days[i][j].setBorder( EMPTY_BORDER );
		    days[i][j].addMouseListener( this );
		}

	ok = new JButton("Ok");
	ok.addActionListener( this );
	cancel = new JButton("Cancel");
	cancel.addActionListener( this );

	JPanel monthYear = new JPanel();
	monthYear.add( month );
	monthYear.add( year );

	daysGrid = new FocusablePanel(new GridLayout(7,7,5,0));
	daysGrid.addFocusListener( this );
	daysGrid.addKeyListener( this );
	for ( int i=0; i<7; i++ )
	    for ( int j=0; j<7; j++ )
		daysGrid.add( days[i][j] );
	daysGrid.setBackground( Color.white );
	daysGrid.setBorder( BorderFactory.createLoweredBevelBorder() );
	JPanel daysPanel = new JPanel();
	daysPanel.add( daysGrid );

	JPanel buttons = new JPanel();
	buttons.add( ok );
	buttons.add( cancel );

	Container dialog = getContentPane();
	dialog.add( "North", monthYear );
	dialog.add( "Center", daysPanel );
	dialog.add( "South", buttons );

	pack();
	setResizable( false );
    }



    /**
     * Gets the selected day, as an <code>int</code>. Parses the text
     * of the selected label in the calendar to get the day.
     *
     * @return the selected day or -1 if there is no day selected
     **/
    private int getSelectedDay()
    {
	if ( day == null )
	    return -1 ;
	try {
	    return Integer.parseInt(day.getText());
	} catch ( NumberFormatException e ) {
	}
	return -1;
    }



    /**
     * Sets the selected day. The day is specified as the label
     * control, in the calendar, corresponding to the day to select.
     *
     * @param newDay day to select
     **/
    private void setSelected( JLabel newDay )
    {
	if ( day != null ) {
	    day.setForeground( DAYS_FOREGROUND );
	    day.setOpaque( false );
	    day.setBorder( EMPTY_BORDER );
	}
	day = newDay;
	day.setForeground( SELECTED_DAY_FOREGROUND );
	day.setOpaque( true );
	if ( daysGrid.hasFocus() )
	    day.setBorder( FOCUSED_BORDER );
    }



    /**
     * Sets the selected day. The day is specified as the number of
     * the day, in the month, to selected. The function compute the
     * corresponding control to select.
     *
     * @param newDay day to select
     **/
    private void setSelected( int newDay )
    {
	setSelected( days[(newDay+offset-1)/7+1][(newDay+offset-1)%7] );
    }



    /**
     * Updates the calendar. This function updates the calendar panel
     * to reflect the month and year selected. It keeps the same day
     * of the month that was selected, except if it is beyond the last
     * day of the month. In this case, the last day of the month is
     * selected.
     **/
    private void update()
    {
	int iday = getSelectedDay();
	for ( int i=0; i<7; i++ ) {
	    days[1][i].setText( " " );
	    days[5][i].setText( " " );
	    days[6][i].setText( " " );
	}
	calendar.set( Calendar.DATE, 1 );
	calendar.set( Calendar.MONTH, month.getSelectedIndex()+Calendar.JANUARY );
	calendar.set( Calendar.YEAR, year.getSelectedIndex()+FIRST_YEAR );

	offset = calendar.get(Calendar.DAY_OF_WEEK)-Calendar.SUNDAY;
	lastDay = calendar.getActualMaximum(Calendar.DATE);
	for ( int i=0; i<lastDay; i++ )
	    days[(i+offset)/7+1][(i+offset)%7].setText( String.valueOf(i+1) );
	if ( iday != -1 ) {
	    if ( iday > lastDay )
		iday = lastDay;
	    setSelected( iday );
	}
    }



    /**
     * Called when the "Ok" button is pressed. Just sets a flag and
     * hides the dialog box.
     **/
    public void actionPerformed( ActionEvent e ) {
	if ( e.getSource() == ok )
	    okClicked = true;
	hide();
    }

    /**
     * Called when the calendar gains the focus. Just re-sets the
     * selected day so that it is redrawn with the border that
     * indicate focus.
     **/
    public void focusGained( FocusEvent e ) {
	setSelected( day );
    }

    /**
     * Called when the calendar loses the focus. Just re-sets the
     * selected day so that it is redrawn without the border that
     * indicate focus.
     **/
    public void focusLost( FocusEvent e ) {
	setSelected( day );
    }

    /**
     * Called when a new month or year is selected. Updates the calendar
     * to reflect the selection.
     **/
    public void itemStateChanged( ItemEvent e ) {
	update();
    }

    /**
     * Called when a key is pressed and the calendar has the
     * focus. Handles the arrow keys so that the user can select a day
     * using the keyboard.
     **/
    public void keyPressed( KeyEvent e ) {
	int iday = getSelectedDay();
	switch ( e.getKeyCode() ) {
	case KeyEvent.VK_LEFT:
	    if ( iday > 1 )
		setSelected( iday-1 );
	    break;
	case KeyEvent.VK_RIGHT:
	    if ( iday < lastDay )
		setSelected( iday+1 );
	    break;
	case KeyEvent.VK_UP:
	    if ( iday > 7 )
		setSelected( iday-7 );
	    break;
	case KeyEvent.VK_DOWN:
	    if ( iday <= lastDay-7 )
		setSelected( iday+7 );
	    break;
	}
    }

    /**
     * Called when the mouse is clicked on a day in the
     * calendar. Selects the clicked day.
     **/
    public void mouseClicked( MouseEvent e ) {
	JLabel day = (JLabel)e.getSource();
	if ( !day.getText().equals(" ") )
	    setSelected( day );
	daysGrid.requestFocus();
    }

    public void keyReleased( KeyEvent e ) {}
    public void keyTyped( KeyEvent e ) {}
    public void mouseEntered( MouseEvent e ) {}
    public void mouseExited( MouseEvent e) {}
    public void mousePressed( MouseEvent e ) {}
    public void mouseReleased( MouseEvent e) {}



    /**
     * Constructs a new <code>DateChooser</code> with the given title.
     *
     * @param owner owner dialog
     *
     * @param title dialog title
     **/
    public DateChooser( Dialog owner, String title )
    {
	super( owner, title, true );
	construct();
    }



    /**
     * Constructs a new <code>DateChooser</code>.
     *
     * @param owner owner dialog
     **/
    public DateChooser( Dialog owner )
    {
	super( owner, true );
	construct();
    }



    /**
     * Constructs a new <code>DateChooser</code> with the given title.
     *
     * @param owner owner frame
     *
     * @param title dialog title
     **/
    public DateChooser( Frame owner, String title )
    {
	super( owner, title, true );
	construct();
    }



    /**
     * Constructs a new <code>DateChooser</code>.
     *
     * @param owner owner frame
     **/
    public DateChooser( Frame owner )
    {
	super( owner, true );
	construct();
    }



    /**
     * Selects a date. Displays the dialog box, with a given date as
     * the selected date, and allows the user select a new date.
     *
     * @param date initial date
     *
     * @return the new date selected or <code>null</code> if the user
     * press "Cancel" or closes the dialog box
     **/
    public Date select( Date date )
    {
	calendar.setTime( date );
	int _day = calendar.get(Calendar.DATE);
	int _month = calendar.get(Calendar.MONTH);
	int _year = calendar.get(Calendar.YEAR);

	year.setSelectedIndex( _year-FIRST_YEAR );
	month.setSelectedIndex( _month-Calendar.JANUARY );
	setSelected( _day );
	okClicked = false;
	show();
	if ( !okClicked )
	    return null;
	calendar.set( Calendar.DATE, getSelectedDay() );
	calendar.set( Calendar.MONTH, month.getSelectedIndex()+Calendar.JANUARY );
	calendar.set( Calendar.YEAR, year.getSelectedIndex()+FIRST_YEAR );
	return calendar.getTime();
    }



    /**
     * Selects new date. Just calls {@link #select(Date)} with the
     * system date as the parameter.
     *
     * @return the same as the function {@link #select(Date)}
     **/
    public Date select()
    {
	return select(new Date());
    }
}

