/* ===================================================
 * JCommon : a free general purpose Java class library
 * ===================================================
 *
 * Project Info:  http://www.jfree.org/jcommon/index.html
 * Project Lead:  David Gilbert (david.gilbert@object-refinery.com);
 *
 * (C) Copyright 2000-2003, by Object Refinery Limited and Contributors.
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * ---------------------
 * DateChooserPanel.java
 * ---------------------
 * (C) Copyright 2000-2003, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * $Id: DateChooserPanel.java,v 1.3 2003/06/12 16:54:38 mungady Exp $
 *
 * Changes (from 26-Oct-2001)
 * --------------------------
 * 26-Oct-2001 : Changed package to com.jrefinery.ui.* (DG);
 * 08-Dec-2001 : Dropped the getMonths() method (DG);
 * 13-Oct-2002 : Fixed errors reported by Checkstyle (DG);
 *
 */

package org.jfree.ui;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Calendar;
import java.util.Date;
import java.util.Enumeration;
import java.util.Vector;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JLabel;
import javax.swing.JPanel;

import org.jfree.date.SerialDate;

/**
 * A panel that allows the user to select a date.
 *
 * @author David Gilbert
 */
public class DateChooserPanel extends JPanel implements ActionListener {

    /** The date selected in the panel. */
    private Calendar chosenDate = null;

    /** The color for the selected date; */
    private Color chosenDateButtonColor = Color.red;

    /** The color for dates in the current month; */
    private Color chosenMonthButtonColor = Color.lightGray;

    /** The color for dates that are visible, but not in the current month; */
    private Color chosenOtherButtonColor = Color.darkGray;

    /** The first day-of-the-week; */
    private int firstDayOfWeek = Calendar.SUNDAY;

    /** The range used for selecting years; */
    private int yearSelectionRange = 20;

    /** The font used to display the date; */
    private Font dateFont = new Font("SansSerif", Font.PLAIN, 10);

    /** A combo for selecting the month; */
    private JComboBox monthSelector = null;

    /** A combo for selecting the year; */
    private JComboBox yearSelector = null;

    /** A button for selecting today's date; */
    private JButton todayButton = null;

    /** An array of buttons used to display the days-of-the-month; */
    private JButton[] buttons = null;

    /** A flag that indicates whether or not we are currently refreshing the buttons; */
    private boolean refreshing = false;

    /**
     * Constructs a new date chooser panel, using today's date as the initial selection.
     */
    public DateChooserPanel() {
        this(Calendar.getInstance(), false);
    }

    /**
     * Constructs a new date chooser panel.
     *
     * @param calendar  the calendar controlling the date.
     * @param controlPanel  a flag that indicates whether or not the 'today' button should
     *                      appear on the panel.
     */
    public DateChooserPanel(Calendar calendar, boolean controlPanel) {

        super(new BorderLayout());
        add(constructSelectionPanel(), BorderLayout.NORTH);
        add(getCalendarPanel(), BorderLayout.CENTER);
        if (controlPanel) {
            add(constructControlPanel(), BorderLayout.SOUTH);
        }
        // the default date is today...
        chosenDate = calendar;
        setDate(calendar.getTime());
    }

    /**
     * Sets the date chosen in the panel.
     *
     * @param theDate  the new date.
     */
    public void setDate(Date theDate) {

        chosenDate.setTime(theDate);
        monthSelector.setSelectedIndex(chosenDate.get(Calendar.MONTH));
        refreshYearSelector();
        refreshButtons();

    }

    /**
     * Returns the date selected in the panel.
     *
     * @return the selected date.
     */
    public Date getDate() {
        return chosenDate.getTime();
    }

    /**
     * Handles action-events from the date panel.
     *
     * @param e information about the event that occurred.
     */
    public void actionPerformed(ActionEvent e) {

        JComboBox c = null;
        Integer y = null;

        if (e.getActionCommand().equals("monthSelectionChanged")) {
            c = (JComboBox) e.getSource();
            chosenDate.set(Calendar.MONTH, c.getSelectedIndex());
            refreshButtons();
        }

        if (e.getActionCommand().equals("yearSelectionChanged")) {
            if (!refreshing) {
                c = (JComboBox) e.getSource();
                y = (Integer) c.getSelectedItem();
                chosenDate.set(Calendar.YEAR, y.intValue());
                refreshYearSelector();
                refreshButtons();
            }
        }

        if (e.getActionCommand().equals("todayButtonClicked")) {
            setDate(new Date());
        }

        if (e.getActionCommand().equals("dateButtonClicked")) {
            JButton b = null;
            b = (JButton) e.getSource();
            int i = Integer.parseInt(b.getName());
            Calendar cal = getFirstVisibleDate();
            cal.add(Calendar.DATE, i);
            setDate(cal.getTime());
        }

    }

    /**
     * Returns a panel of buttons, each button representing a day in the month.  This is a
     * sub-component of the DatePanel.
     *
     * @return the panel.
     */
    private JPanel getCalendarPanel() {

        JPanel p = null;
        JButton b = null;

        p = new JPanel(new GridLayout(7, 7));
        p.add(new JLabel("Sun", JLabel.CENTER));
        p.add(new JLabel("Mon", JLabel.CENTER));
        p.add(new JLabel("Tue", JLabel.CENTER));
        p.add(new JLabel("Wed", JLabel.CENTER));
        p.add(new JLabel("Thu", JLabel.CENTER));
        p.add(new JLabel("Fri", JLabel.CENTER));
        p.add(new JLabel("Sat", JLabel.CENTER));

        buttons = new JButton[42];
        for (int i = 0; i < 42; i++) {
            b = new JButton("");
            b.setMargin(new Insets(1, 1, 1, 1));
            b.setName(new Integer(i).toString());
            b.setFont(dateFont);
            b.setFocusPainted(false);
            b.setActionCommand("dateButtonClicked");
            b.addActionListener(this);
            buttons[i] = b;
            p.add(b);
        }
        return p;

    }

    /**
     * Returns the button color according to the specified date.
     *
     * @param theDate  the date.
     *
     * @return the color.
     */
    private Color getButtonColor(Calendar theDate) {
        if (equalDates(theDate, chosenDate)) {
            return chosenDateButtonColor;
        }
        else if (theDate.get(Calendar.MONTH) == chosenDate.get(Calendar.MONTH)) {
            return chosenMonthButtonColor;
        }
        else {
            return chosenOtherButtonColor;
        }
    }

    /**
     * Returns true if the two dates are equal (time of day is ignored).
     *
     * @param c1  the first date.
     * @param c2  the second date.
     *
     * @return boolean.
     */
    private boolean equalDates(Calendar c1, Calendar c2) {
        if ((c1.get(Calendar.DATE) == c2.get(Calendar.DATE))
            && (c1.get(Calendar.MONTH) == c2.get(Calendar.MONTH))
            && (c1.get(Calendar.YEAR) == c2.get(Calendar.YEAR))) {
            return true;
        }
        else {
            return false;
        }
    }

    /**
     * Returns the first date that is visible in the grid.  This should always be in the month
     * preceding the month of the selected date.
     *
     * @return the date.
     */
    private Calendar getFirstVisibleDate() {
        Calendar c = Calendar.getInstance();
        c.set(chosenDate.get(Calendar.YEAR), chosenDate.get(Calendar.MONTH), 1);
        c.add(Calendar.DATE, -1);
        while (c.get(Calendar.DAY_OF_WEEK) != getFirstDayOfWeek()) {
            c.add(Calendar.DATE, -1);
        }
        return c;
    }

    /**
     * Returns the first day of the week (controls the labels in the date panel).
     *
     * @return the first day of the week.
     */
    private int getFirstDayOfWeek() {
        return firstDayOfWeek;
    }

    /**
     * Update the button labels and colors to reflect date selection.
     */
    private void refreshButtons() {
        JButton b = null;
        Calendar c = getFirstVisibleDate();
        for (int i = 0; i < 42; i++) {
            b = buttons[i];
            b.setText(new Integer(c.get(Calendar.DATE)).toString());
            b.setBackground(getButtonColor(c));
            c.add(Calendar.DATE, 1);
        }
    }

    /**
     * Changes the contents of the year selection JComboBox to reflect the chosen date and the
     * year range.
     */
    private void refreshYearSelector() {
        if (!refreshing) {
            refreshing = true;
            yearSelector.removeAllItems();
            Vector v = getYears(chosenDate.get(Calendar.YEAR));
            for (Enumeration e = v.elements(); e.hasMoreElements();) {
                yearSelector.addItem(e.nextElement());
            }
            yearSelector.setSelectedItem(new Integer(chosenDate.get(Calendar.YEAR)));
            refreshing = false;
        }
    }

    /**
     * Returns a vector of years preceding and following the specified year.  The number of
     * years preceding and following is determined by the yearSelectionRange attribute.
     *
     * @param chosenYear  the selected year.
     *
     * @return a vector of years.
     */
    private Vector getYears(int chosenYear) {
        Vector v = null;
        v = new Vector();
        for (int i = chosenYear - yearSelectionRange; i <= chosenYear + yearSelectionRange; i++) {
            v.addElement(new Integer(i));
        }
        return v;
    }

    /**
     * Constructs a panel containing two JComboBoxes (for the month and year) and a button (to
     * reset the date to TODAY).
     *
     * @return the panel.
     */
    private JPanel constructSelectionPanel() {
        JPanel p = null;

        p = new JPanel();
        monthSelector = new JComboBox(SerialDate.getMonths());
        monthSelector.addActionListener(this);
        monthSelector.setActionCommand("monthSelectionChanged");
        p.add(monthSelector);

        yearSelector = new JComboBox(getYears(0));
        yearSelector.addActionListener(this);
        yearSelector.setActionCommand("yearSelectionChanged");
        p.add(yearSelector);

        return p;
    }

    /**
     * Returns a panel that appears at the bottom of the calendar panel - contains a button for
     * selecting today's date.
     *
     * @return the panel.
     */
    private JPanel constructControlPanel() {

        JPanel p = new JPanel();
        p.setBorder(BorderFactory.createEmptyBorder(2, 5, 2, 5));
        todayButton = new JButton("Today");
        todayButton.addActionListener(this);
        todayButton.setActionCommand("todayButtonClicked");
        p.add(todayButton);
        return p;

    }

}