/**
    * Copyright 2005-2013 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.kew.xml.xstream;
  
  import java.util.List;
  
  import javax.xml.xpath.XPath;
  import javax.xml.xpath.XPathExpressionException;
  import javax.xml.xpath.XPathFunction;
  import javax.xml.xpath.XPathFunctionException;
  
  import org.w3c.dom.Node;
  
  /**
   * An XPathFunction which will run XStream safe XPath queries.
   * 
   * @see XStreamSafeEvaluator
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class XStreamSafeSearchFunction implements XPathFunction {
  
  	private final Node rootNode;
  	private XPath xpath;
  	private static XStreamSafeEvaluator evaluator = new XStreamSafeEvaluator();
  	
  	public XStreamSafeSearchFunction(Node rootNode, XPath xpath) {
  		this.rootNode = rootNode;
  		this.xpath = xpath;
  	}
  	
  	public Object evaluate(List parameters) throws XPathFunctionException {
  		String xPathExpression = getXPathExpressionParameter(parameters);
  		evaluator.setXpath(xpath);
  		//Node rootSearchNode = getRootSearchNodeParameter(parameters);
  		try {
  			return evaluator.evaluate(xPathExpression, rootNode);
  		} catch (XPathExpressionException e) {
  			throw new XPathFunctionException(e);
  		}
  	}
  	
  	private String getXPathExpressionParameter(List parameters) throws XPathFunctionException {
  		if (parameters.size() < 1) {
  			throw new XPathFunctionException("First parameter must be an XPath expression.");
  		}
  		if (!(parameters.get(0) instanceof String)) {
  			throw new XPathFunctionException("First parameter must be an XPath expression String");
  		}
  		return (String)parameters.get(0);
  	}
  
  	public XPath getXpath() {
  		return xpath;
  	}
  
  	public void setXpath(XPath xpath) {
  		this.xpath = xpath;
  	}
  	
  	/*private Node getRootSearchNodeParameter(List parameters) throws XPathFunctionException {
  		if (parameters.size() < 2) {
  			throw new XPathFunctionException("Second parameter should be root node and is required");
  		}
  		System.out.println(parameters.get(1));
  		if (!(parameters.get(1) instanceof Node)) {
  			throw new XPathFunctionException("Second parameter should be an instance of Node (try using the root() XPath function).");
  		}
  		return (Node)parameters.get(1);
  	}*/
  
  }