/**
    * Copyright 2005-2015 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();
      }
  }