/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/**

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements. See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership. The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License. You may obtain a copy of the License at

 *

 * http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing,

 * software distributed under the License is distributed on an

 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

 * KIND, either express or implied. See the License for the

 * specific language governing permissions and limitations

 * under the License.

 */

package com.sun.org.apache.xml.internal.security.c14n.helper;

import com.sun.org.apache.xml.internal.security.utils.Constants;

import org.w3c.dom.Attr;

import java.io.Serializable;

import java.util.Comparator;

/**

 * Compares two attributes based on the C14n specification.

 *

 * <UL>

 * <LI>Namespace nodes have a lesser document order position than attribute

 *   nodes.

 * <LI> An element's namespace nodes are sorted lexicographically by

 *   local name (the default namespace node, if one exists, has no

 *   local name and is therefore lexicographically least).

 * <LI> An element's attribute nodes are sorted lexicographically with

 *   namespace URI as the primary key and local name as the secondary

 *   key (an empty namespace URI is lexicographically least).

 * </UL>

 *

 */

public class AttrCompare implements Comparator<Attr>, Serializable {

    private static final long serialVersionUID = -7113259629930576230L;

    private static final int ATTR0_BEFORE_ATTR1 = -1;

    private static final int ATTR1_BEFORE_ATTR0 = 1;

    private static final String XMLNS = Constants.NamespaceSpecNS;

    /**

     * Compares two attributes based on the C14n specification.

     *

     * <UL>

     * <LI>Namespace nodes have a lesser document order position than

     *   attribute nodes.

     * <LI> An element's namespace nodes are sorted lexicographically by

     *   local name (the default namespace node, if one exists, has no

     *   local name and is therefore lexicographically least).

     * <LI> An element's attribute nodes are sorted lexicographically with

     *   namespace URI as the primary key and local name as the secondary

     *   key (an empty namespace URI is lexicographically least).

     * </UL>

     *

     * @param attr0

     * @param attr1

     * @return returns a negative integer, zero, or a positive integer as

     *   obj0 is less than, equal to, or greater than obj1

     *

     */

    public int compare(Attr attr0, Attr attr1) {

        String namespaceURI0 = attr0.getNamespaceURI();

        String namespaceURI1 = attr1.getNamespaceURI();

        boolean isNamespaceAttr0 = XMLNS.equals(namespaceURI0);

        boolean isNamespaceAttr1 = XMLNS.equals(namespaceURI1);

        if (isNamespaceAttr0) {

            if (isNamespaceAttr1) {

                // both are namespaces

                String localname0 = attr0.getLocalName();

                String localname1 = attr1.getLocalName();

                if ("xmlns".equals(localname0)) {

                    localname0 = "";

                }

                if ("xmlns".equals(localname1)) {

                    localname1 = "";

                }

                return localname0.compareTo(localname1);

            }

            // attr0 is a namespace, attr1 is not

            return ATTR0_BEFORE_ATTR1;

        } else if (isNamespaceAttr1) {

            // attr1 is a namespace, attr0 is not

            return ATTR1_BEFORE_ATTR0;

        }

        // none is a namespace

        if (namespaceURI0 == null) {

            if (namespaceURI1 == null) {

                String name0 = attr0.getName();

                String name1 = attr1.getName();

                return name0.compareTo(name1);

            }

            return ATTR0_BEFORE_ATTR1;

        } else if (namespaceURI1 == null) {

            return ATTR1_BEFORE_ATTR0;

        }

        int a = namespaceURI0.compareTo(namespaceURI1);

        if (a != 0) {

            return a;

        }

        return attr0.getLocalName().compareTo(attr1.getLocalName());

    }

}