/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Copyright  1999-2004 The Apache Software Foundation.
 *
 *  Licensed 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.

Namespace nodes have a lesser document order position than attribute
  nodes.
 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).
 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).

Author:
Christian Geuer-Pollmann/**
 * 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>
 *
 * @author Christian Geuer-Pollmann
 */
public class AttrCompare implements Comparator, Serializable {

    private final static long serialVersionUID = -7113259629930576230L;
    private final static int ATTR0_BEFORE_ATTR1 = -1;
    private final static int ATTR1_BEFORE_ATTR0 = 1;
    private final static String XMLNS=Constants.NamespaceSpecNS;

    
Compares two attributes based on the C14n specification.

Namespace nodes have a lesser document order position than
  attribute nodes.
 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).
 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).

Params:
obj0 – casted Attr
obj1 – casted Attr
Returns:
returns a negative integer, zero, or a positive integer as
  obj0 is less than, equal to, or greater than obj1/**
     * 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 obj0 casted Attr
     * @param obj1 casted Attr
     * @return returns a negative integer, zero, or a positive integer as
     *   obj0 is less than, equal to, or greater than obj1
     *
     */
    public int compare(Object obj0, Object obj1) {

        Attr attr0 = (Attr) obj0;
        Attr attr1 = (Attr) obj1;
        String namespaceURI0 = attr0.getNamespaceURI();
        String namespaceURI1 = attr1.getNamespaceURI();

        boolean isNamespaceAttr0 = XMLNS==namespaceURI0;
        boolean isNamespaceAttr1 = XMLNS==namespaceURI1;

        if (isNamespaceAttr0) {
            if (isNamespaceAttr1) {
                // both are namespaces
                String localname0 = attr0.getLocalName();
                String localname1 = attr1.getLocalName();

                if (localname0.equals("xmlns")) {
                    localname0 = "";
                }

                if (localname1.equals("xmlns")) {
                    localname1 = "";
                }

                return localname0.compareTo(localname1);
            }
            // attr0 is a namespace, attr1 is not
            return ATTR0_BEFORE_ATTR1;
        }

        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;
        }

        if (namespaceURI1 == null) {
            return ATTR1_BEFORE_ATTR0;
        }

        int a = namespaceURI0.compareTo(namespaceURI1);
        if (a != 0) {
            return a;
        }

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