package org.jaxen.dom4j;
   
   /*
    * $Header$
    * $Revision$
    * $Date$
    *
    * ====================================================================
    *
   * Copyright 2000-2005 bob mcwhirter & James Strachan.
   * All rights reserved.
   *
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   * 
   *   * Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   * 
   *   * Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   * 
   *   * Neither the name of the Jaxen Project nor the names of its
   *     contributors may be used to endorse or promote products derived 
   *     from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * ====================================================================
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Jaxen Project and was originally
   * created by bob mcwhirter <bob@werken.com> and
   * James Strachan <jstrachan@apache.org>.  For more information on the
   * Jaxen Project, please see <http://www.jaxen.org/>.
   *
   * $Id$
  */
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  
  import org.dom4j.Attribute;
  import org.dom4j.Branch;
  import org.dom4j.CDATA;
  import org.dom4j.Comment;
  import org.dom4j.Document;
  import org.dom4j.DocumentException;
  import org.dom4j.Element;
  import org.dom4j.Namespace;
  import org.dom4j.Node;
  import org.dom4j.ProcessingInstruction;
  import org.dom4j.QName;
  import org.dom4j.Text;
  import org.dom4j.io.SAXReader;
  import org.jaxen.DefaultNavigator;
  import org.jaxen.FunctionCallException;
  import org.jaxen.NamedAccessNavigator;
  import org.jaxen.Navigator;
  import org.jaxen.XPath;
  import org.jaxen.JaxenConstants;
  import org.jaxen.saxpath.SAXPathException;
  import org.jaxen.util.SingleObjectIterator;
  
  /** 
   * Interface for navigating around the DOM4J object model.
   *
   * <p>
   * This class is not intended for direct usage, but is
   * used by the Jaxen engine during evaluation.
   * </p>
   *
   * @see XPath
   *
   * @author <a href="mailto:bob@werken.com">bob mcwhirter</a>
   * @author Stephen Colebourne
   */
  public class DocumentNavigator extends DefaultNavigator implements NamedAccessNavigator
  {
      
  
      private static final long serialVersionUID = 5582300797286535936L;
      private transient SAXReader reader;
  
      /** Singleton implementation.
       */
     private static class Singleton
     {
         /** Singleton instance.
          */
         private static DocumentNavigator instance = new DocumentNavigator();
     }
 
     /** Retrieve the singleton instance of this <code>DocumentNavigator</code>.
      */
     public static Navigator getInstance()
     {
         return Singleton.instance;
     }
 
     public boolean isElement(Object obj)
     {
         return obj instanceof Element;
     }
 
     public boolean isComment(Object obj)
     {
         return obj instanceof Comment;
     }
 
     public boolean isText(Object obj)
     {
         return ( obj instanceof Text 
                  ||
                  obj instanceof CDATA );
     }
 
     public boolean isAttribute(Object obj)
     {
         return obj instanceof Attribute;
     }
 
     public boolean isProcessingInstruction(Object obj)
     {
         return obj instanceof ProcessingInstruction;
     }
 
     public boolean isDocument(Object obj)
     {
         return obj instanceof Document;
     }
 
     public boolean isNamespace(Object obj)
     {
         return obj instanceof Namespace;
     }
 
     public String getElementName(Object obj)
     {
         Element elem = (Element) obj;
 
         return elem.getName();
     }
 
     public String getElementNamespaceUri(Object obj)
     {
         Element elem = (Element) obj;
         
         String uri = elem.getNamespaceURI();
         if ( uri == null)
             return "";
         else
             return uri;
     }
 
     public String getElementQName(Object obj)
     {
         Element elem = (Element) obj;
 
         return elem.getQualifiedName();
     }
 
     public String getAttributeName(Object obj)
     {
         Attribute attr = (Attribute) obj;
 
         return attr.getName();
     }
 
     public String getAttributeNamespaceUri(Object obj)
     {
         Attribute attr = (Attribute) obj;
 
         String uri = attr.getNamespaceURI();
         if ( uri == null)
             return "";
         else
             return uri;
     }
 
     public String getAttributeQName(Object obj)
     {
         Attribute attr = (Attribute) obj;
 
         return attr.getQualifiedName();
     }
 
     public Iterator getChildAxisIterator(Object contextNode)
     {
         Iterator result = null;
         if ( contextNode instanceof Branch )
         {
             Branch node = (Branch) contextNode;
             result = node.nodeIterator();
         }
         if (result != null) {
             return result;
         }
         return JaxenConstants.EMPTY_ITERATOR;
     }
 
     /**
      * Retrieves an <code>Iterator</code> over the child elements that
      * match the supplied name.
      *
      * @param contextNode      the origin context node
      * @param localName        the local name of the children to return, always present
      * @param namespacePrefix  the prefix of the namespace of the children to return
      * @param namespaceURI     the uri of the namespace of the children to return
      * 
      * @return an Iterator that traverses the named children, or null if none
      */
     public Iterator getChildAxisIterator(
             Object contextNode, String localName, String namespacePrefix, String namespaceURI) {
 
         if ( contextNode instanceof Element ) {
             Element node = (Element) contextNode;
             return node.elementIterator(QName.get(localName, namespacePrefix, namespaceURI));
         }
         if ( contextNode instanceof Document ) {
             Document node = (Document) contextNode;
             Element el = node.getRootElement();
             if (el == null || el.getName().equals(localName) == false) {
                 return JaxenConstants.EMPTY_ITERATOR;
             }
             if (namespaceURI != null) {
                 if (namespaceURI.equals(el.getNamespaceURI()) == false) {
                     return JaxenConstants.EMPTY_ITERATOR;
                 }
             }
             return new SingleObjectIterator(el);
         }
 
         return JaxenConstants.EMPTY_ITERATOR;
     }
 
     public Iterator getParentAxisIterator(Object contextNode)
     {
         if ( contextNode instanceof Document )
         {
             return JaxenConstants.EMPTY_ITERATOR;
         }
 
         Node node = (Node) contextNode;
 
         Object parent = node.getParent();
 
         if ( parent == null )
         {
             parent = node.getDocument();
         }
         
         return new SingleObjectIterator( parent );
     }
 
     public Iterator getAttributeAxisIterator(Object contextNode)
     {
         if ( ! ( contextNode instanceof Element ) )
         {
             return JaxenConstants.EMPTY_ITERATOR;
         }
 
         Element elem = (Element) contextNode;
 
         return elem.attributeIterator();
     }
 
     /**
      * Retrieves an <code>Iterator</code> over the attribute elements that
      * match the supplied name.
      *
      * @param contextNode  the origin context node
      * @param localName  the local name of the attributes to return, always present
      * @param namespacePrefix  the prefix of the namespace of the attributes to return
      * @param namespaceURI  the URI of the namespace of the attributes to return
      * @return an Iterator that traverses the named attributes, not null
      */
     public Iterator getAttributeAxisIterator(
             Object contextNode, String localName, String namespacePrefix, String namespaceURI) {
 
         if ( contextNode instanceof Element ) {
             Element node = (Element) contextNode;
             Attribute attr = node.attribute(QName.get(localName, namespacePrefix, namespaceURI));
             if (attr == null) {
                 return JaxenConstants.EMPTY_ITERATOR;
             }
             return new SingleObjectIterator(attr);
         }
         return JaxenConstants.EMPTY_ITERATOR;
     }
         
     public Iterator getNamespaceAxisIterator(Object contextNode)
     {
         if ( ! ( contextNode instanceof Element ) )
         {
             return JaxenConstants.EMPTY_ITERATOR;
         }
 
         Element element = (Element) contextNode;
         List nsList = new ArrayList();
         HashSet prefixes = new HashSet();
         for ( Element context = element; context != null; context = context.getParent() ) {
             List declaredNS = new ArrayList(context.declaredNamespaces());
             declaredNS.add(context.getNamespace());
 
             for ( Iterator iter = context.attributes().iterator(); iter.hasNext(); )
             {
                 Attribute attr = (Attribute) iter.next();
                 declaredNS.add(attr.getNamespace());
             }
 
             for ( Iterator iter = declaredNS.iterator(); iter.hasNext(); )
             {
                 Namespace namespace = (Namespace) iter.next();
                 if (namespace != Namespace.NO_NAMESPACE)
                 {
                     String prefix = namespace.getPrefix();
                     if ( ! prefixes.contains( prefix ) ) {
                         prefixes.add( prefix );
                         nsList.add( namespace.asXPathResult( element ) );
                     }
                 }
             }
         }
         nsList.add( Namespace.XML_NAMESPACE.asXPathResult( element ) );
         return nsList.iterator();
     }
 
     public Object getDocumentNode(Object contextNode)
     {
         if ( contextNode instanceof Document ) 
         {
             return contextNode;
         }
         else if ( contextNode instanceof Node ) 
         {
             Node node = (Node) contextNode;
             return node.getDocument();
         }
         return null;
     }
 
     /** Returns a parsed form of the given XPath string, which will be suitable
      *  for queries on DOM4J documents.
      */
     public XPath parseXPath (String xpath) throws SAXPathException
     {
         return new Dom4jXPath(xpath);
     }
 
     public Object getParentNode(Object contextNode)
     {
         if ( contextNode instanceof Node ) 
         {
             Node node = (Node) contextNode;
             Object answer = node.getParent();
             if ( answer == null ) 
             {
                 answer = node.getDocument();
                 if (answer == contextNode) {
                     return null;
                 }
             }
             return answer;            
         }
         return null;
     }
 
     public String getTextStringValue(Object obj)
     {
         return getNodeStringValue( (Node) obj );
     }
 
     public String getElementStringValue(Object obj)
     {
         return getNodeStringValue( (Node) obj );
     }
 
     public String getAttributeStringValue(Object obj)
     {
         return getNodeStringValue( (Node) obj );
     }
 
     private String getNodeStringValue(Node node)
     {
         return node.getStringValue();
     }
 
     public String getNamespaceStringValue(Object obj)
     {
         Namespace ns = (Namespace) obj;
 
         return ns.getURI();
     }
 
     public String getNamespacePrefix(Object obj)
     {
         Namespace ns = (Namespace) obj;
 
         return ns.getPrefix();
     }
 
     public String getCommentStringValue(Object obj)
     {
         Comment cmt = (Comment) obj;
 
         return cmt.getText();
     }
     
     public String translateNamespacePrefixToUri(String prefix, Object context)
     {
         Element element = null;
         if ( context instanceof Element ) 
         {
             element = (Element) context;
         }
         else if ( context instanceof Node )
         {
             Node node = (Node) context;
             element = node.getParent();
         }
         if ( element != null )
         {
             Namespace namespace = element.getNamespaceForPrefix( prefix );
 
             if ( namespace != null ) 
             {
                 return namespace.getURI();
             }
         }
         return null;
     }
     
     public short getNodeType(Object node) 
     {
         if ( node instanceof Node )
         {
             return ((Node) node).getNodeType();
         }
         return 0;
     }
     
     public Object getDocument(String uri) throws FunctionCallException
     {
         try
         {
             return getSAXReader().read( uri );
         }
         catch (DocumentException e)
         {
             throw new FunctionCallException("Failed to parse document for URI: " + uri, e);
         }
     }
 
     public String getProcessingInstructionTarget(Object obj)
     {
         ProcessingInstruction pi = (ProcessingInstruction) obj;
 
         return pi.getTarget();
     }
 
     public String getProcessingInstructionData(Object obj)
     {
         ProcessingInstruction pi = (ProcessingInstruction) obj;
 
         return pi.getText();
     }
     
     // Properties
     //-------------------------------------------------------------------------    
     public SAXReader getSAXReader()
     {
         if ( reader == null ) 
         {
             reader = new SAXReader();
             reader.setMergeAdjacentText( true );
         }
         return reader;
     }
     
     public void setSAXReader(SAXReader reader)
     {
         this.reader = reader;
     }
     
 }