/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 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 end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``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 THE APACHE SOFTWARE FOUNDATION OR
 * ITS 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 Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.xalan.lib;

import org.w3c.dom.Node;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
import org.w3c.dom.traversal.NodeIterator;
import org.apache.xpath.NodeSet;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.objects.XBoolean;
import org.apache.xpath.objects.XNumber;
import org.apache.xpath.XPath;
import org.apache.xpath.XPathContext;
import org.apache.xpath.DOMHelper;
import org.xml.sax.SAXNotSupportedException;
import java.util.Hashtable;
import java.util.StringTokenizer;

import org.apache.xalan.extensions.ExpressionContext;

/**
 * <meta name="usage" content="general"/>
 * This class contains many of the Xalan-supplied extensions.
 * It is accessed by specifying a namespace URI as follows:
 * <pre>
 *    xmlns:xalan="http://xml.apache.org/xalan"
 * </pre>
 */

public class Extensions {

  private Extensions() {}	// Make sure class cannot be instantiated

  /**
   * This method is an extension that implements as a Xalan extension
   * the node-set function also found in xt and saxon.
   * If the argument is a Result Tree Fragment, then <code>nodeset</code>
   * returns a node-set consisting of a single root node as described in
   * section 11.1 of the XSLT 1.0 Recommendation.  If the argument is a 
   * node-set, <code>nodeset</code> returns a node-set.  If the argument
   * is a string, number, or boolean, then <code>nodeset</code> returns
   * a node-set consisting of a single root node with a single text node
   * child that is the result of calling the XPath string() function on the 
   * passed parameter.  If the argument is anything else, then a node-set
   * is returned consisting of a single root node with a single text node
   * child that is the result of calling the java <code>toString()</code>
   * method on the passed argument.
   * Most of the
   * actual work here is done in <code>MethodResolver</code> and
   * <code>XRTreeFrag</code>.
   * @param myProcessor Context passed by the extension processor
   * @param rtf Argument in the stylesheet to the nodeset extension function
   */

  public static NodeSet nodeset(ExpressionContext myProcessor, Object rtf) {

    String textNodeValue;

    if (rtf instanceof NodeIterator)
    {
      return new NodeSet((NodeIterator) rtf);
    }
    else
    {
      if (rtf instanceof String)
      {
        textNodeValue = (String) rtf;
      }
      else if (rtf instanceof Boolean)
      {
        textNodeValue = new XBoolean(((Boolean) rtf).booleanValue()).str();
      }
      else if (rtf instanceof Double)
      {
        textNodeValue = new XNumber(((Double) rtf).doubleValue()).str();
      }
      else
      {
        textNodeValue = rtf.toString();
      }
      Document myDoc = myProcessor.getContextNode().getOwnerDocument();
      Text textNode = myDoc.createTextNode(textNodeValue);
      DocumentFragment docFrag = myDoc.createDocumentFragment();
      docFrag.appendChild(textNode);
      return new NodeSet(docFrag);
    }
  }
  
	/**
	 * Returns the intersection of two node-sets.
	 * @param n1 NodeIterator for first node-set
	 * @param ni2 NodeIterator for second node-set
	 * @return a NodeSet containing the nodes in ni1 that are also
	 * in ni2
	 */	
	public static NodeSet intersection(NodeIterator ni1, NodeIterator ni2)
			throws javax.xml.transform.TransformerException
	{
		NodeSet ns1 = new NodeSet(ni1);
		NodeSet ns2 = new NodeSet(ni2);
		NodeSet inter= new NodeSet();
		inter.setShouldCacheNodes(true);
		for (int i=0; i < ns1.getLength(); i++)
		{
			Node n = ns1.elementAt(i);
			if(ns2.contains(n))
				inter.addElement(n);
		}
		return inter;
	}
	
	/**
	 * Returns the difference between two node-sets.
	 * @param n1 NodeIterator for first node-set
	 * @param ni2 NodeIterator for second node-set
	 * @return a NodeSet containing the nodes in ni1 that are not
	 * in ni2
	 */	
	public static NodeSet difference(NodeIterator ni1, NodeIterator ni2)
			throws javax.xml.transform.TransformerException	
	{
		NodeSet ns1 = new NodeSet(ni1);
		NodeSet ns2 = new NodeSet(ni2);
		// NodeSet inter= new NodeSet();
		NodeSet diff = new NodeSet();
		diff.setShouldCacheNodes(true);		
		for (int i = 0; i < ns1.getLength(); i++)
		{
			Node n = ns1.elementAt(i);
			if(!ns2.contains(n))
				diff.addElement(n);
		}
		return diff;
	}

	/**
	 * Returns node-set containing distinct string values.
	 * @param ni NodeIterator for node-set
	 * @return a NodeSet with nodes from ni containing distinct string values. 
	 * In other words, if more than one node in ni contains the same string value, 
	 * only include the first such node found.
	 */	
	public static NodeSet distinct(NodeIterator ni)
			throws javax.xml.transform.TransformerException	
	{
		NodeSet ns = new NodeSet(ni);
		NodeSet dist = new NodeSet();
		dist.setShouldCacheNodes(true);		
		Hashtable stringTable = new Hashtable();
		for (int i = 0; i < ns.getLength(); i++)
		{
			Node n = ns.elementAt(i);
      String key = DOMHelper.getNodeData(n);
      if (!stringTable.containsKey(key))
			{
        stringTable.put(key, n);
        dist.addElement(n);
			}
		}
		return dist;
	}

	/**
	 * Returns true of both node-sets contain the same set of nodes.
	 * @param n1 NodeIterator for first node-set
	 * @param ni2 NodeIterator for second node-set
	 * @return true if ni1 and ni2 contain exactly the same set of nodes.
	 */	
	public static boolean hasSameNodes(NodeIterator ni1, NodeIterator ni2)
	{
		NodeSet ns1 = new NodeSet(ni1);
		NodeSet ns2 = new NodeSet(ni2);		
		if (ns1.getLength() != ns2.getLength())
			return false;
		for (int i = 0; i < ns1.getLength(); i++)
		{
			Node n = ns1.elementAt(i);
			if(!ns2.contains(n))
				return false;
		}
		return true;
	}  

	/**
	 * Returns the result of evaluating the argument as a string containing
   * an XPath expression.  Used where the XPath expression is not known until
   * run-time.  The expression is evaluated as if the run-time value of the
   * argument appeared in place of the evaluate function call at compile time.
	 * @param myContext an <code>ExpressionContext</code> passed in by the
   *                  extension mechanism.  This must be an XPathContext.
	 * @param xpathExtr The XPath expression to be evaluated.
	 * @return the XObject resulting from evaluating the XPath
	 */	
	public static XObject evaluate(ExpressionContext myContext, String xpathExpr)
                  throws SAXNotSupportedException, Exception
	{
    if (myContext instanceof XPathContext)
    {
      try
      {
        XPathContext xctxt = (XPathContext) myContext;
        XPath dynamicXPath = new XPath(xpathExpr,
                                  xctxt.getSAXLocator(),
                                  xctxt.getNamespaceContext(),
                                  XPath.SELECT);
        return dynamicXPath.execute(xctxt,
                                    myContext.getContextNode(),
                                    xctxt.getNamespaceContext());
      }
      catch (Exception e)
      {
        throw e;
      }
    }
    else
      throw new SAXNotSupportedException("Invalid context passed to evaluate " + myContext);
	}  

	/**
	 * Returns a NodeSet containing one text node for each token in the first argument.
   * Delimiters are specified in the second argument.
   * Tokens are determined by a call to <code>StringTokenizer</code>.
   * If the first argument is an empty string or contains only delimiters, the result
   * will be an empty NodeSet.
   * Contributed to XalanJ1 by <a href="mailto:benoit.cerrina@writeme.com">Benoit Cerrina</a>.  
	 * @param myContext an <code>ExpressionContext</code> passed in by the
   *                  extension mechanism.  This must be an XPathContext.
	 * @param toTokenize The string to be split into text tokens.
   * @param delims The delimiters to use.
	 * @return a NodeSet as described above.
   *
	 */	
	public static NodeSet tokenize(ExpressionContext myContext, String toTokenize, String delims)
	{
    Document lDoc = myContext.getContextNode().getOwnerDocument();
    StringTokenizer lTokenizer = new StringTokenizer(toTokenize, delims);
    NodeSet resultSet = new NodeSet();
    while (lTokenizer.hasMoreTokens())
    {
      resultSet.addNode(lDoc.createTextNode(lTokenizer.nextToken()));
    }
    return resultSet;
}  

	/**
	 * Returns a NodeSet containing one text node for each token in the first argument.
   * Delimiters are whitespace.  That is, the delimiters that are used are tab (&#x09),
   * linefeed (&#x0A), return (&#x0D), and space (&#x20).
   * Tokens are determined by a call to <code>StringTokenizer</code>.
   * If the first argument is an empty string or contains only delimiters, the result
   * will be an empty NodeSet.
   * Contributed to XalanJ1 by <a href="mailto:benoit.cerrina@writeme.com">Benoit Cerrina</a>.  
	 * @param myContext an <code>ExpressionContext</code> passed in by the
   *                  extension mechanism.  This must be an XPathContext.
	 * @param toTokenize The string to be split into text tokens.
	 * @return a NodeSet as described above.
   *
	 */	
	public static NodeSet tokenize(ExpressionContext myContext, String toTokenize)
	{
    return tokenize(myContext, toTokenize, " \t\n\r");
  }  

}