/*

  * Copyright 2007-2008 The Kuali Foundation

  * 

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  * 

  * 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 org.kuali.rice.ken.util;

 import java.util.HashMap;

 import java.util.HashSet;

 import java.util.Iterator;

 import java.util.Map;

 import javax.xml.namespace.NamespaceContext;

 import org.apache.log4j.Logger;

 /**

  * XPath NamespaceContext that is configured with a predefined prefix->NS map.

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class ConfiguredNamespaceContext implements NamespaceContext {

     private static final Logger LOG = Logger.getLogger(ConfiguredNamespaceContext.class);

     private Map<String, String> prefixToNamespace = new HashMap<String, String>();

     private Map<String, HashSet<String>> namespaceToPrefix = new HashMap<String, HashSet<String>>();

     /**

      * Constructs a ConfiguredNamespaceContext.java.

      * @param prefixToNamespace

      */

     public ConfiguredNamespaceContext(Map<String, String> prefixToNamespace) {

         this.prefixToNamespace = prefixToNamespace;

         // create a reverse namespace to prefix(es) map

         for (Map.Entry<String, String> entry: prefixToNamespace.entrySet()) {

             String namespace = entry.getValue();

             String prefix = entry.getKey();

             HashSet<String> prefixes = namespaceToPrefix.get(namespace);

             if (prefixes == null) {

                 prefixes = new HashSet<String>(4);

                 namespaceToPrefix.put(namespace, prefixes);

             }

             prefixes.add(prefix);

         }

     }

     /**

      * @see javax.xml.namespace.NamespaceContext#getNamespaceURI(java.lang.String)

      */

     public String getNamespaceURI(String prefix) {

         //LOG.trace("getNamespaceURI(" + prefix + ")");

         if (prefix == null) {

             throw new IllegalArgumentException("The prefix cannot be null.");

         }

         return prefixToNamespace.get(prefix);

     }

     /**

      * @see javax.xml.namespace.NamespaceContext#getPrefix(java.lang.String)

      */

     public String getPrefix(String namespaceURI) {

         //LOG.trace("getPrefix(" + namespaceURI + ")");

         if (namespaceURI == null) {

             throw new IllegalArgumentException("The namespace uri cannot be null.");

         }

         Iterator<String> prefixes = getPrefixes(namespaceURI);

         if (prefixes != null) {

             return prefixes.next();

         } else {

             return null;

         }

     }

     /**

      * @see javax.xml.namespace.NamespaceContext#getPrefixes(java.lang.String)

      */

     public Iterator<String> getPrefixes(String namespaceURI) {

         //LOG.trace("getPrefixes(" + namespaceURI + ")");

         if (namespaceURI == null) {

             throw new IllegalArgumentException("The namespace uri cannot be null.");

         }

         HashSet<String> prefixes = namespaceToPrefix.get(namespaceURI);

         if (prefixes != null && prefixes.size() > 0) {

             return prefixes.iterator();

         } else {

             return null;

         }

     }

 }