/**
    * 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 org.apache.ws.security.message.token;
  
  import javax.xml.namespace.QName;
  
  import org.apache.ws.security.WSConstants;
  import org.apache.ws.security.WSSecurityException;
  import org.apache.ws.security.util.DOM2Writer;
  import org.apache.ws.security.util.WSSecurityUtil;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.Node;
  
  /**
   * Reference.
   * 
   * @author Davanum Srinivas (dims@yahoo.com).
   */
  public class Reference {
      public static final QName TOKEN = new QName(WSConstants.WSSE_NS, "Reference");
      protected Element element = null;
      
      /**
       * Constructor.
       * 
       * @param elem The Reference element
       * @throws WSSecurityException 
       */
      public Reference(Element elem) throws WSSecurityException {
          if (elem == null) {
              throw new WSSecurityException(WSSecurityException.INVALID_SECURITY, "noReference");
          }
          element = elem;
          QName el = new QName(element.getNamespaceURI(), element.getLocalName());
          if (!el.equals(TOKEN)) {
              throw new WSSecurityException(
                  WSSecurityException.FAILURE, "badElement", new Object[] {TOKEN, el}
              );
          }
  
          String uri = getURI();
          // Reference URI cannot be null or empty
          if (uri == null || "".equals(uri)) {
              throw new WSSecurityException(
                  WSSecurityException.INVALID_SECURITY, "badReferenceURI"
              );
          }
      }
  
      /**
       * Constructor.
       * 
       * @param doc 
       */
      public Reference(Document doc) {
          element = doc.createElementNS(WSConstants.WSSE_NS, "wsse:Reference");
      }
      
      /**
       * Add the WSSE Namespace to this reference. The namespace is not added by default for
       * efficiency purposes, as the reference is embedded in a wsse:SecurityTokenReference.
       */
      public void addWSSENamespace() {
          WSSecurityUtil.setNamespace(this.element, WSConstants.WSSE_NS, WSConstants.WSSE_PREFIX);
      }
  
      /**
       * Get the DOM element.
       * 
       * @return the DOM element
       */
      public Element getElement() {
          return element;
      }
  
      /**
       * Get the ValueType attribute.
       * 
       * @return the ValueType attribute
       */
      public String getValueType() {
         return element.getAttribute("ValueType");
     }
 
     /**
      * Get the URI.
      * 
      * @return the URI
      */
     public String getURI() {
         return element.getAttribute("URI");
     }
 
     /**
      * Set the Value type.
      * 
      * @param valueType the ValueType attribute to set
      */
     public void setValueType(String valueType) {
         element.setAttributeNS(null, "ValueType", valueType);
     }
 
     /**
      * Set the URI.
      * 
      * @param uri the URI to set
      */
     public void setURI(String uri) {
         element.setAttributeNS(null, "URI", uri);
     }
 
     /**
      * Return the string representation.
      * 
      * @return the string representation.
      */
     public String toString() {
         return DOM2Writer.nodeToString((Node)element);
     }
     
     @Override
     public int hashCode() {
         int result = 17;
         String uri = getURI();
         if (uri != null) {
             result = 31 * result + uri.hashCode();
         }
         String valueType = getValueType();
         if (valueType != null) {
             result = 31 * result + valueType.hashCode();
         }
         return result;
     }
     
     @Override
     public boolean equals(Object object) {
         if (!(object instanceof Reference)) {
             return false;
         }
         Reference reference = (Reference)object;
         if (!compare(getURI(), reference.getURI())) {
             return false;
         }
         if (!compare(getValueType(), reference.getValueType())) {
             return false;
         }
         return true;
     }
     
     private boolean compare(String item1, String item2) {
         if (item1 == null && item2 != null) { 
             return false;
         } else if (item1 != null && !item1.equals(item2)) {
             return false;
         }
         return true;
     }
 }