/*
    * Copyright 2005-2008 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.edl.components;
  
  import javax.xml.xpath.XPath;
  import javax.xml.xpath.XPathConstants;
  import javax.xml.xpath.XPathExpressionException;
  
  import org.apache.commons.lang.StringUtils;
  import org.kuali.rice.kew.edl.EDLContext;
  import org.kuali.rice.kew.edl.EDLModelComponent;
  import org.kuali.rice.kew.rule.xmlrouting.XPathHelper;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  
  
  
  /**
   * Looks at a field definition for a select field and attempts to analyze and resolve any valuesGroups based on document data.
   * The result of this is to take a fieldDef that has a valuesGroup and either remove it if it does not match or replace the
   * <valuesGroup> element with a series of <values> elements that include the values contained with the values group.
   * 
   * <p>This allows for <select> fields to be dependent upon one another. 
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class SelectControlEDLComponent implements EDLModelComponent {
  
  	public void updateDOM(Document dom, Element currentDefinitionElement, EDLContext edlContext) {
  	    Element currentVersion = VersioningPreprocessor.findCurrentVersion(dom);
  	    XPath xPath = XPathHelper.newXPath(dom);
  	    try {
  		NodeList selectFieldDefs = (NodeList)xPath.evaluate("//fieldDef[display/type = 'select' and display/valuesGroup] | //fieldDef[display/type = 'select_refresh' and display/valuesGroup]", dom, XPathConstants.NODESET);
  		for (int fIndex = 0; fIndex < selectFieldDefs.getLength(); fIndex++) {
  		    Element fieldDef = (Element)selectFieldDefs.item(fIndex);
  		NodeList valuesGroups = (NodeList)xPath.evaluate("./display/valuesGroup", fieldDef, XPathConstants.NODESET);
  		for (int index = 0; index < valuesGroups.getLength(); index++) {
  		    Element valuesGroupElem = (Element)valuesGroups.item(index);
  		    NodeList dependsOnFields = (NodeList)xPath.evaluate("./dependsOn/field", valuesGroupElem, XPathConstants.NODESET);
  		    String fieldEvalExpression = "";
  		    for (int dIndex = 0; dIndex < dependsOnFields.getLength(); dIndex++) {
  			if (!StringUtils.isBlank(fieldEvalExpression)) {
  			    fieldEvalExpression += " and ";
  			}
  			Element fieldElem = (Element)dependsOnFields.item(dIndex);
  			String name = fieldElem.getAttribute("name");
  			String value = fieldElem.getTextContent();
  			fieldEvalExpression += "./field[@name='" + name + "']/value = '" + value + "'";
  		    }
  		    if ((Boolean)xPath.evaluate(fieldEvalExpression, currentVersion, XPathConstants.BOOLEAN)) {
  			includeValuesGroup(valuesGroupElem);
  		    } else {
  			// remove the valuesGroup as it did not match
  			valuesGroupElem.getParentNode().removeChild(valuesGroupElem);
  		    }
  		}
  		}
  	    } catch (XPathExpressionException e) {
  		throw new RuntimeException("Failed to evaluate xpath expression.", e);
  	    }
  	}
  	
  	protected void includeValuesGroup(Element valuesGroupElem) {
  	    Element valuesGroupParent = (Element)valuesGroupElem.getParentNode();
  	    NodeList valuesGroupChildren = valuesGroupElem.getChildNodes();
  	    
  	    for (int index = 0; index < valuesGroupChildren.getLength(); index++) {
  		Node item = valuesGroupChildren.item(index);
  		if (Node.ELEMENT_NODE == item.getNodeType() && item.getNodeName().equals("values")) {
  		    valuesGroupParent.insertBefore(item, valuesGroupElem);
  		}
  	    }
  	    valuesGroupParent.removeChild(valuesGroupElem);
  	}	
  	
  }