/**

  * Copyright 2005-2011 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.edl.impl.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.edl.impl.EDLContext;

 import org.kuali.rice.edl.impl.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);

         }        

 }