/*
    * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
    *
    * This software is open source.
    * See the bottom of this file for the licence.
    */
   
   package org.dom4j.xpath;
   
  import java.io.Serializable;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import org.dom4j.InvalidXPathException;
  import org.dom4j.Node;
  import org.dom4j.NodeFilter;
  import org.dom4j.XPathException;
  
  import org.jaxen.FunctionContext;
  import org.jaxen.JaxenException;
  import org.jaxen.NamespaceContext;
  import org.jaxen.SimpleNamespaceContext;
  import org.jaxen.VariableContext;
  import org.jaxen.XPath;
  import org.jaxen.dom4j.Dom4jXPath;
  
  /***
   * <p>
   * Default implementation of {@link org.dom4j.XPath}which uses the <a
   * href="http://jaxen.org">Jaxen </a> project.
   * </p>
   * 
   * @author bob mcwhirter
   * @author <a href="mailto:jstrachan@apache.org">James Strachan </a>
   */
  public class DefaultXPath implements org.dom4j.XPath, NodeFilter, Serializable {
      private String text;
  
      private XPath xpath;
  
      private NamespaceContext namespaceContext;
  
      /***
       * Construct an XPath
       * 
       * @param text
       *            DOCUMENT ME!
       * 
       * @throws InvalidXPathException
       *             DOCUMENT ME!
       */
      public DefaultXPath(String text) throws InvalidXPathException {
          this.text = text;
          this.xpath = parse(text);
      }
  
      public String toString() {
          return "[XPath: " + xpath + "]";
      }
  
      // XPath interface
  
      /***
       * Retrieve the textual XPath string used to initialize this Object
       * 
       * @return The XPath string
       */
      public String getText() {
          return text;
      }
  
      public FunctionContext getFunctionContext() {
          return xpath.getFunctionContext();
      }
  
      public void setFunctionContext(FunctionContext functionContext) {
          xpath.setFunctionContext(functionContext);
      }
  
      public NamespaceContext getNamespaceContext() {
          return namespaceContext;
      }
  
      public void setNamespaceURIs(Map map) {
          setNamespaceContext(new SimpleNamespaceContext(map));
      }
  
      public void setNamespaceContext(NamespaceContext namespaceContext) {
          this.namespaceContext = namespaceContext;
          xpath.setNamespaceContext(namespaceContext);
      }
  
      public VariableContext getVariableContext() {
          return xpath.getVariableContext();
     }
 
     public void setVariableContext(VariableContext variableContext) {
         xpath.setVariableContext(variableContext);
     }
 
     public Object evaluate(Object context) {
         try {
             setNSContext(context);
 
             List answer = xpath.selectNodes(context);
 
             if ((answer != null) && (answer.size() == 1)) {
                 return answer.get(0);
             }
 
             return answer;
         } catch (JaxenException e) {
             handleJaxenException(e);
 
             return null;
         }
     }
 
     public Object selectObject(Object context) {
         return evaluate(context);
     }
 
     public List selectNodes(Object context) {
         try {
             setNSContext(context);
 
             return xpath.selectNodes(context);
         } catch (JaxenException e) {
             handleJaxenException(e);
 
             return Collections.EMPTY_LIST;
         }
     }
 
     public List selectNodes(Object context, org.dom4j.XPath sortXPath) {
         List answer = selectNodes(context);
         sortXPath.sort(answer);
 
         return answer;
     }
 
     public List selectNodes(Object context, org.dom4j.XPath sortXPath,
             boolean distinct) {
         List answer = selectNodes(context);
         sortXPath.sort(answer, distinct);
 
         return answer;
     }
 
     public Node selectSingleNode(Object context) {
         try {
             setNSContext(context);
 
             Object answer = xpath.selectSingleNode(context);
 
             if (answer instanceof Node) {
                 return (Node) answer;
             }
 
             if (answer == null) {
                 return null;
             }
 
             throw new XPathException("The result of the XPath expression is "
                     + "not a Node. It was: " + answer + " of type: "
                     + answer.getClass().getName());
         } catch (JaxenException e) {
             handleJaxenException(e);
 
             return null;
         }
     }
 
     public String valueOf(Object context) {
         try {
             setNSContext(context);
 
             return xpath.stringValueOf(context);
         } catch (JaxenException e) {
             handleJaxenException(e);
 
             return "";
         }
     }
 
     public Number numberValueOf(Object context) {
         try {
             setNSContext(context);
 
             return xpath.numberValueOf(context);
         } catch (JaxenException e) {
             handleJaxenException(e);
 
             return null;
         }
     }
 
     public boolean booleanValueOf(Object context) {
         try {
             setNSContext(context);
 
             return xpath.booleanValueOf(context);
         } catch (JaxenException e) {
             handleJaxenException(e);
 
             return false;
         }
     }
 
     /***
      * <p>
      * <code>sort</code> sorts the given List of Nodes using this XPath
      * expression as a {@link Comparator}.
      * </p>
      * 
      * @param list
      *            is the list of Nodes to sort
      */
     public void sort(List list) {
         sort(list, false);
     }
 
     /***
      * <p>
      * <code>sort</code> sorts the given List of Nodes using this XPath
      * expression as a {@link Comparator}and optionally removing duplicates.
      * </p>
      * 
      * @param list
      *            is the list of Nodes to sort
      * @param distinct
      *            if true then duplicate values (using the sortXPath for
      *            comparisions) will be removed from the List
      */
     public void sort(List list, boolean distinct) {
         if ((list != null) && !list.isEmpty()) {
             int size = list.size();
             HashMap sortValues = new HashMap(size);
 
             for (int i = 0; i < size; i++) {
                 Object object = list.get(i);
 
                 if (object instanceof Node) {
                     Node node = (Node) object;
                     Object expression = getCompareValue(node);
                     sortValues.put(node, expression);
                 }
             }
 
             sort(list, sortValues);
 
             if (distinct) {
                 removeDuplicates(list, sortValues);
             }
         }
     }
 
     public boolean matches(Node node) {
         try {
             setNSContext(node);
 
             List answer = xpath.selectNodes(node);
 
             if ((answer != null) && (answer.size() > 0)) {
                 Object item = answer.get(0);
 
                 if (item instanceof Boolean) {
                     return ((Boolean) item).booleanValue();
                 }
 
                 return answer.contains(node);
             }
 
             return false;
         } catch (JaxenException e) {
             handleJaxenException(e);
 
             return false;
         }
     }
 
     /***
      * Sorts the list based on the sortValues for each node
      * 
      * @param list
      *            DOCUMENT ME!
      * @param sortValues
      *            DOCUMENT ME!
      */
     protected void sort(List list, final Map sortValues) {
         Collections.sort(list, new Comparator() {
             public int compare(Object o1, Object o2) {
                 o1 = sortValues.get(o1);
                 o2 = sortValues.get(o2);
 
                 if (o1 == o2) {
                     return 0;
                 } else if (o1 instanceof Comparable) {
                     Comparable c1 = (Comparable) o1;
 
                     return c1.compareTo(o2);
                 } else if (o1 == null) {
                     return 1;
                 } else if (o2 == null) {
                     return -1;
                 } else {
                     return o1.equals(o2) ? 0 : (-1);
                 }
             }
         });
     }
 
     // Implementation methods
 
     /***
      * Removes items from the list which have duplicate values
      * 
      * @param list
      *            DOCUMENT ME!
      * @param sortValues
      *            DOCUMENT ME!
      */
     protected void removeDuplicates(List list, Map sortValues) {
         // remove distinct
         HashSet distinctValues = new HashSet();
 
         for (Iterator iter = list.iterator(); iter.hasNext();) {
             Object node = iter.next();
             Object value = sortValues.get(node);
 
             if (distinctValues.contains(value)) {
                 iter.remove();
             } else {
                 distinctValues.add(value);
             }
         }
     }
 
     /***
      * DOCUMENT ME!
      * 
      * @param node
      *            DOCUMENT ME!
      * 
      * @return the node expression used for sorting comparisons
      */
     protected Object getCompareValue(Node node) {
         return valueOf(node);
     }
 
     protected static XPath parse(String text) {
         try {
             return new Dom4jXPath(text);
         } catch (JaxenException e) {
             throw new InvalidXPathException(text, e.getMessage());
         } catch (Throwable t) {
         	throw new InvalidXPathException(text, t);
         }
     }
 
     protected void setNSContext(Object context) {
         if (namespaceContext == null) {
             xpath.setNamespaceContext(DefaultNamespaceContext.create(context));
         }
     }
 
     protected void handleJaxenException(JaxenException exception)
             throws XPathException {
         throw new XPathException(text, exception);
     }
 }
 
 /*
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  * ("Software"), with or without modification, are permitted provided that the
  * following conditions are met:
  * 
  * 1. Redistributions of source code must retain copyright statements and
  * notices. Redistributions must also contain a copy of this document.
  * 
  * 2. 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.
  * 
  * 3. The name "DOM4J" must not be used to endorse or promote products derived
  * from this Software without prior written permission of MetaStuff, Ltd. For
  * written permission, please contact dom4j-info@metastuff.com.
  * 
  * 4. Products derived from this Software may not be called "DOM4J" nor may
  * "DOM4J" appear in their names without prior written permission of MetaStuff,
  * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
  * 
  * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
  * 
  * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESSED 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 METASTUFF, LTD. OR ITS CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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  * 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.
  * 
  * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
  */