/*
 * Copyright (c) 2004, Stefan Walter
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above
 *       copyright notice, this list of conditions and the
 *       following disclaimer.
 *     * Redistributions in binary form must reproduce the
 *       above copyright notice, this list of conditions and
 *       the following disclaimer in the documentation and/or
 *       other materials provided with the distribution.
 *     * The names of contributors to this software may not be
 *       used to endorse or promote products derived from this
 *       software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 *
 * CONTRIBUTORS
 *  Stefan Walter <stef@memberwebs.com>
 *
 */

package com.memberwebs.ldapxml.helpers;

import java.util.Comparator;

import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * Used to sort XML elements according to a specified sort order
 *
 * @author stef@memberwebs.com
 * @version 0.5
 */
public class LXComparator
        implements Comparator
{
    /**
     * Construct a new LXComparator
     *
     * @param attrs The element or attribute names to sort by
     * @param directions The sort direction for each attr
     */
    public LXComparator(String[] attrs, boolean[] directions)
    {
        m_attrs = attrs;
        m_directions = directions;
    }

    /**
     * Compare two objects and return -1, 0 or 1
     *
     * @param o1 The first object
     * @param o2 The second object
     */
    public int compare(Object o1, Object o2)
    {
        Element e1 = (Element)o1;
        Element e2 = (Element)o2;

        for(int i = 0; i < m_attrs.length; i++)
        {
            String v1 = getSubElementValue(e1, m_attrs[i]);
            String v2 = getSubElementValue(e2, m_attrs[i]);

            int ret;

            if(v1 == null && v2 == null)
                ret = 0;
            else if(v1 == null)
                ret = -1;
            else if(v2 == null)
                ret = 1;
            else
                ret = v1.compareTo(v2);

            if(ret != 0)
                return m_directions[i] ? ret : -ret;
        }

        return 0;
    }

    /**
     * Check whether another comparator is equal to this one.
     *
     * @param obj The other comparator
     * @return Whether equal or not
     */
    public boolean equals(Object obj)
    {
        LXComparator other = (LXComparator)obj;
        return m_attrs.equals(other.m_attrs) &&
                m_directions.equals(other.m_directions);
    }

    /**
     * Get a value from an element. The value is either retrieved
     * from a sub element of the appropriate name or an attribute
     * of the same name.
     *
     * @param el The element to retrieve from.
     * @param attr The value name
     */
    private static String getSubElementValue(Element el, String attr)
    {
        // First we search sub elements and then attributes
        if(el.hasChildNodes())
        {
            NodeList children = el.getChildNodes();
            for(int i = 0; i < children.getLength(); i++)
            {
                Node child = children.item(i);
                if(child != null &&
                   child.getNodeType() == Node.ELEMENT_NODE &&
                   child.getNodeName().equals(attr))
                {
                    return getElementValue(el);
                }
            }
        }

        // Otherwise try to get the attribute by the same name
        return el.getAttribute(attr);
    }

    /**
     * Get the complete text value of an element.
     *
     * @param el The element to retrieve value for
     * @return The value.
     */
    private static String getElementValue(Element el)
    {
        String value = "";

        if(el.hasChildNodes())
        {
            NodeList children = el.getChildNodes();
            for(int i = 0; i < children.getLength(); i++)
            {
                Node child = children.item(i);
                if(child != null)
                {
                    switch(child.getNodeType())
                    {
                    case Node.ELEMENT_NODE:
                        value += getElementValue((Element)child);
                        break;
                    case Node.TEXT_NODE:
                        value += child.getNodeValue();
                        break;
                    }
                }
            }
        }

        return value;
    }

    private String[] m_attrs;
    private boolean[] m_directions;
}