/*
 This file is part of the software framework JStatCom, 
 a library for building applications for data based analysis.

 Copyright (C) 2000-2005  Alexander Benkwitz, Markus Kraetzig

 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
 */

package com.jstatcom.component;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;

import javax.swing.AbstractAction;
import javax.swing.Icon;
import javax.swing.JComponent;
import javax.swing.JPanel;
import javax.swing.SwingConstants;

import org.apache.log4j.Logger;

/**
 * An action for the task of showing a "card" component in a
 * CardDisplayPanel.
 * 

 * The "card" component is only constructed when getComponent is
 * called the first time. This way the component gets only created when the
 * respective CardPanelAction is actually called. This may led to
 * faster program start.
 * 
 * @author A. Benkwitz, M. Kraetzig
 * @see com.jstatcom.component.CardDisplayPanel
 */
public final class CardPanelAction extends AbstractAction {
    private static final Logger log = Logger.getLogger(CardPanelAction.class);

    private final CardDisplayPanel cardPanel;

    private JComponent component = null;

    private final String className;

    /**
     * Creates an action object that constructs a component on demand according
     * to the arguments.
     * 
     * @param className
     *            the string with the fully qualified class name of the
     *            component to construct when this action is called
     * @param parent
     *            the parent panel
     * @param enabled
     *            true if this action should be enabled
     * @param name
     *            the name of this action
     * 
     * @throws IllegalArgumentException
     *             if (className == null) or
     *             if (parent == null)
     */
    public CardPanelAction(String className, CardDisplayPanel parent,
            boolean enabled, String name) {

        this(className, parent, enabled, name, null);

    }

    /**
     * Creates an action object that constructs a component on demand according
     * to the arguments.
     * 
     * @param className
     *            the string with the fully qualified class name of the
     *            component to construct when this action is called
     * @param parent
     *            the parent panel
     * @param enabled
     *            true if this action should be enabled
     * @param name
     *            the name of this action
     * @param icon
     *            an icon to be displayed by components taking this
     *            AbstractAction as argument
     * 
     * @throws IllegalArgumentException
     *             if (className == null) or
     *             if (parent == null)
     */
    public CardPanelAction(String className, CardDisplayPanel parent,
            boolean enabled, String name, Icon icon) {

        super(name, icon);

        if (className == null)
            throw new IllegalArgumentException("Class name was null.");
        if (parent == null)
            throw new IllegalArgumentException("Parent was null.");

        this.className = className;

        cardPanel = parent;
        setEnabled(enabled);
    }

    /**
     * Invoked when this action is called. Creates the respective component if
     * it has not been created before and calls showCard of the
     * parent CardDisplayPanel.
     * 
     * @param arg1
     *            argument is ignored and can be null
     */
    public void actionPerformed(ActionEvent arg1) {
        cardPanel.showCard(getComponent());
    }

    /**
     * Gets the component defined via className in the
     * constructor. If this method is called the first time, the component is
     * first created.
     * 
     * @return the component that has been defined via its class name in the
     *         constructor of this action, if the object construction failes, am
     *         empty JPanel with a message is returned
     */
    public JComponent getComponent() {
        if (component == null) {
            try {
                component = (JComponent) Class.forName(className).newInstance();
            } catch (Throwable thr) {
                String msg = "Problem creating \"" + className + "\".";
                log.error(msg, thr);
                component = new JPanel();
                component.setLayout(new BorderLayout());
                MultiLineLabel label = new MultiLineLabel(
                        msg
                                + "\nDisplaying an empty JPanel instead. Check log messages for more.");
                label.setHorizontalAlignment(SwingConstants.CENTER);
                label.setForeground(Color.red);
                component.add(label, "Center");
            }
        }
        return component;
    }
}