/* ===================================================
 * 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.
 *
 * ---------------------------
 * SerialDateChooserPanel.java
 * ---------------------------
 * (C) Copyright 2001-2003, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * $Id: SerialDateChooserPanel.java,v 1.3 2003/06/12 16:54:42 mungady Exp $
 *
 * Changes
 * -------
 * 08-Dec-2001 : Version 1 (DG);
 * 14-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.
 * <P>
 * This class is incomplete and untested.  You should not use it yet...
 *
 * @author David Gilbert
 */
public class SerialDateChooserPanel extends JPanel implements ActionListener {

    /** The default background color for the selected date. */
    public static final Color DEFAULT_DATE_BUTTON_COLOR = Color.red;

    /** The default background color for the current month. */
    public static final Color DEFAULT_MONTH_BUTTON_COLOR = Color.lightGray;

    /** The date selected in the panel. */
    private SerialDate date;

    /** The color for the selected date; */
    private Color dateButtonColor;

    /** The color for dates in the current month; */
    private Color monthButtonColor;

    /** 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 SerialDateChooserPanel() {

        this(SerialDate.createInstance(new Date()), false,
             DEFAULT_DATE_BUTTON_COLOR,
             DEFAULT_MONTH_BUTTON_COLOR);

    }

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

        this(date, controlPanel,
             DEFAULT_DATE_BUTTON_COLOR,
             DEFAULT_MONTH_BUTTON_COLOR);

    }

    /**
     * Constructs a new date chooser panel.
     *
     * @param date  the date.
     * @param controlPanel  the control panel.
     * @param dateButtonColor  the date button color.
     * @param monthButtonColor  the month button color.
     */
    public SerialDateChooserPanel(SerialDate date, boolean controlPanel,
                                  Color dateButtonColor, Color monthButtonColor) {

        super(new BorderLayout());

        this.date = date;
        this.dateButtonColor = dateButtonColor;
        this.monthButtonColor = monthButtonColor;

        add(constructSelectionPanel(), BorderLayout.NORTH);
        add(getCalendarPanel(), BorderLayout.CENTER);
        if (controlPanel) {
            add(constructControlPanel(), BorderLayout.SOUTH);
        }

    }

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

        this.date = date;
        monthSelector.setSelectedIndex(date.getMonth() - 1);
        refreshYearSelector();
        refreshButtons();

    }

    /**
     * Returns the date selected in the panel.
     *
     * @return the selected date.
     */
    public SerialDate getDate() {
        return this.date;
    }

    /**
     * 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();
            date = SerialDate.createInstance(date.getDayOfMonth(), c.getSelectedIndex() + 1,
                                             date.getYYYY());
            refreshButtons();
        }

        if (e.getActionCommand().equals("yearSelectionChanged")) {
            if (!refreshing) {
                c = (JComboBox) e.getSource();
                y = (Integer) c.getSelectedItem();
                date = SerialDate.createInstance(date.getDayOfMonth(), date.getMonth(),
                                                 y.intValue());
                refreshYearSelector();
                refreshButtons();
            }
        }

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

        if (e.getActionCommand().equals("dateButtonClicked")) {
            JButton b = null;
            b = (JButton) e.getSource();
            int i = Integer.parseInt(b.getName());
            SerialDate first = getFirstVisibleDate();
            SerialDate selected = SerialDate.addDays(i, first);
            setDate(selected);
        }

    }

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

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

    }

    /**
     * Returns the button color according to the specified date.
     *
     * @param targetDate  the target date.
     *
     * @return the button color.
     */
    protected Color getButtonColor(SerialDate targetDate) {

        if (this.date.equals(date)) {
            return dateButtonColor;
        }
        else if (targetDate.getMonth() == date.getMonth()) {
            return monthButtonColor;
        }
        else {
            return chosenOtherButtonColor;
        }

    }

    /**
     * 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 first visible date.
     */
    protected SerialDate getFirstVisibleDate() {

        SerialDate result = SerialDate.createInstance(1, date.getMonth(), date.getYYYY());
        result = SerialDate.addDays(-1, result);
        while (result.getDayOfWeek() != getFirstDayOfWeek()) {
            result = SerialDate.addDays(-1, result);
        }
        return result;

    }

    /**
     * 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.
     */
    protected void refreshButtons() {

        SerialDate current = getFirstVisibleDate();
        for (int i = 0; i < 42; i++) {
            JButton button = buttons[i];
            button.setText(String.valueOf(current.getDayOfWeek()));
            button.setBackground(getButtonColor(current));
            current = SerialDate.addDays(1, current);
        }

    }

    /**
     * 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(date.getYYYY());
            for (Enumeration e = v.elements(); e.hasMoreElements();) {
                yearSelector.addItem(e.nextElement());
            }
            yearSelector.setSelectedItem(new Integer(date.getYYYY()));
            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 current 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;

    }

}