/*

  * 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.ArrayList;

 import java.util.Iterator;

 import java.util.List;

 import javax.xml.namespace.NamespaceContext;

 import org.apache.log4j.Logger;

 import org.w3c.dom.Document;

 /**

  * XPath NamespaceContext implementation that delegates all lookups to a DOM Document,

  * which supplies all prefix/NS mappings defined in the doc.

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

  */

 public class DocumentNamespaceContext implements NamespaceContext {

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

     // the DOM Document

     private final Document doc;

     /**

      * Constructs a DocumentNamespaceContext.java.

      * @param doc

      */

     public DocumentNamespaceContext(Document doc) {

         this.doc = doc;

     }

     /**

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

      */

     public String getNamespaceURI(String prefix) {

         LOG.debug("getNamespaceURI(" + prefix + ")");

         if (prefix == null) {

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

         }

         if (prefix.length() == 0) {

             return doc.lookupNamespaceURI(null);

         }

         return doc.lookupNamespaceURI(prefix);

     }

     /**

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

      */

     public String getPrefix(String namespaceURI) {

         LOG.debug("getPrefix(" + namespaceURI + ")");

         if (namespaceURI == null) {

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

         }

         return doc.lookupPrefix(namespaceURI);

     }

     /**

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

      */

     public Iterator getPrefixes(String namespaceURI) {

         LOG.debug("getPrefixes(" + namespaceURI + ")");

         if (namespaceURI == null) {

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

         }

         List<String> list = new ArrayList<String>(1);

         String s = getPrefix(namespaceURI);

         if (s != null) {

             list.add(s);

         }

         return list.iterator();

     }

 }