/*

  * Copyright 2007-2008 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.role;

 import org.apache.commons.lang.StringUtils;

 import org.kuali.rice.core.api.exception.RiceRuntimeException;

 import org.kuali.rice.core.util.AttributeSet;

 import org.kuali.rice.core.util.xml.XmlJotter;

 import org.kuali.rice.kew.engine.RouteContext;

 import org.kuali.rice.kew.rule.XmlConfiguredAttribute;

 import org.kuali.rice.kew.rule.bo.RuleAttribute;

 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;

 import org.xml.sax.InputSource;

 import javax.xml.xpath.XPath;

 import javax.xml.xpath.XPathConstants;

 import javax.xml.xpath.XPathExpressionException;

 import java.io.StringReader;

 import java.util.ArrayList;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 /**

  * Resolves qualifiers based on XPath configuration in the resolver's attribute.

  * 

  * <p>An example of the xml processed by this attribute follows:

  * 

  * <p><pre>

  * <resolverConfig>

  *   <baseXPathExpression>/xmlData/chartOrg</baseXPathExpression>

  *   <qualifier name="chart">

  *     <xPathExpression>./chart</xPathExpression>

  *   </qualifier>

  *   <qualifier name="org">

  *     <xPathExpression>./org</xPathExpression>

  *   </qualifier>

  * </resolverConfig>

  * </pre>

  * 

  * <p>There are 2 different types of qualifier resolvers, those that resolve compound

  * attribute sets and those that resolve simple attribute sets.  A simple attribute

  * set is one which includes only a single "qualifier" specification.  The example above

  * is compound because it includes both chart and org.

  * 

  * <p>When dealing with compound attribute sets, the baseXPathExpression is used to

  * define grouping for these compound sets.  It is therefore required that inside each

  * resulting element retrieved from the baseXPathExpression, there is only a single instance

  * of each qualifier.  If this is not the case, an error will be thrown.  For the example

  * above, the following XML would be evaluated successfully:

  * 

  * <p><pre>

  * <xmlData>

  *   <chartOrg>

  *     <chart>BL</chart>

  *     <org>BUS</org>

  *   </chartOrg>

  *   <chartOrg>

  *     <chart>IN</chart>

  *     <org>MED</org>

  *   </chartOrg>

  * </xmlData>

  * </pre>

  * 

  * <p>This would return 2 attributes sets, each with a chart and org in it.  The following

  * XML would cause the XPathQualifierResolver to throw an exception during processing.

  * 

  * <p><pre>

  * <xmlData>

  *   <chartOrg>

  *     <chart>BL</chart>

  *     <org>BUS</org>

  *     <chart>IN</chart>

  *     <org>MED</org>

  *   </chartOrg>

  * </xmlData>

  * </pre>

  * 

  * <p>In this case the resolver has no knowledge of how to group chart and org together.

  * What follows is an example of a resolver using a simple attribute set:

  * 

  * <p><pre>

  * <resolverConfig>

  *   <baseXPathExpression>/xmlData/accountNumbers</baseXPathExpression>

  *   <qualifier name="accountNumber">

  *     <xPathExpression>./accountNumber</xPathExpression>

  *   </qualifier>

  * </resolverConfig>

  * </pre>

  * 

  * <p>In this example, the following XML would return a List containing an AttributeSet

  * for each account number when resolved.

  * 

  * <p><pre>

  * <xmlData>

  *   <accountNumbers>

  *     <accountNumber>12345</accountNumber>

  *     <accountNumber>54321</accountNumber>

  *     <accountNumber>102030</accountNumber>

  *     <accountNumber>302010</accountNumber>

  *   </accountNumbers>

  * </xmlData>

  * 

  * <p>The baseXPathExpression is optional and defaults to the root of the document if not specified.

  * 

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class XPathQualifierResolver implements QualifierResolver, XmlConfiguredAttribute {

     private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(XPathQualifierResolver.class);

         private RuleAttribute ruleAttribute;

         public List<AttributeSet> resolve(RouteContext context) {

                         ResolverConfig config = parseResolverConfig();

                         Document xmlContent = context.getDocumentContent().getDocument();

                         XPath xPath = XPathHelper.newXPath();

                         boolean isCompoundAttributeSet = config.getExpressionMap().size() > 1;

                         try {

                                 List<AttributeSet> attributeSets = new ArrayList<AttributeSet>();

                                 NodeList baseElements = (NodeList)xPath.evaluate(config.getBaseXPathExpression(), xmlContent, XPathConstants.NODESET);

                                 if (LOG.isDebugEnabled()) {

                                         LOG.debug("Found " + baseElements.getLength() + " baseElements to parse for AttributeSets using document XML:" + XmlJotter.jotDocument(xmlContent));

                                 }

                                 for (int index = 0; index < baseElements.getLength(); index++) {

                                         Node baseNode = baseElements.item(index);

                                         if (isCompoundAttributeSet) {

                                                 handleCompoundAttributeSet(baseNode, attributeSets, config, xPath);

                                         } else {

                                                 handleSimpleAttributeSet(baseNode, attributeSets, config, xPath);

                                         }

                                 }

                                 return attributeSets;

                         } catch (XPathExpressionException e) {

                                 throw new RiceRuntimeException("Encountered an issue executing XPath.", e);

                         }

         }

         protected void handleCompoundAttributeSet(Node baseNode, List<AttributeSet> attributeSets, ResolverConfig config, XPath xPath) throws XPathExpressionException {

                 AttributeSet attributeSet = new AttributeSet();

                 for (String attributeName : config.getExpressionMap().keySet()) {

                         String xPathExpression = config.getExpressionMap().get(attributeName);

                         NodeList attributes = (NodeList)xPath.evaluate(xPathExpression, baseNode, XPathConstants.NODESET);

                         if (attributes.getLength() > 1) {

                                 throw new RiceRuntimeException("Found more than more XPath result for an attribute in a compound attribute set for attribute: " + attributeName + " with expression " + xPathExpression);

                         } else if (attributes.getLength() != 0) {

                                 String attributeValue = ((Element)attributes.item(0)).getTextContent();

                                 if (LOG.isDebugEnabled()) {

                                         LOG.debug("Adding values to compound AttributeSet: " + attributeName + "::" + attributeValue);

                                 }

                                 attributeSet.put(attributeName, attributeValue);

                         }

                 }

                 attributeSets.add(attributeSet);

         }

         protected void handleSimpleAttributeSet(Node baseNode, List<AttributeSet> attributeSets, ResolverConfig config, XPath xPath) throws XPathExpressionException {

                 String attributeName = config.getExpressionMap().keySet().iterator().next();

                 String xPathExpression = config.getExpressionMap().get(attributeName);

                 NodeList attributes = (NodeList)xPath.evaluate(xPathExpression, baseNode, XPathConstants.NODESET);

                 for (int index = 0; index < attributes.getLength(); index++) {

                         Element attributeElement = (Element)attributes.item(index);

                         AttributeSet attributeSet = new AttributeSet();

                         String attributeValue = attributeElement.getTextContent();

                         if (LOG.isDebugEnabled()) {

                                 LOG.debug("Adding values to simple AttributeSet: " + attributeName + "::" + attributeValue);

                         }

                         attributeSet.put(attributeName, attributeValue);

                         attributeSets.add(attributeSet);

                 }

         }

         public void setRuleAttribute(RuleAttribute ruleAttribute) {

                 this.ruleAttribute = ruleAttribute;

         }

         protected ResolverConfig parseResolverConfig() {

                 if (ruleAttribute == null) {

                         throw new RiceRuntimeException("Failed to locate a RuleAttribute for the given XPathQualifierResolver");

                 }

                 try {

                         ResolverConfig resolverConfig = new ResolverConfig();

                         String xmlConfig = ruleAttribute.getXmlConfigData();

                         XPath xPath = XPathHelper.newXPath();

                         String baseExpression = xPath.evaluate("//resolverConfig/baseXPathExpression", new InputSource(new StringReader(xmlConfig)));

                         if (!StringUtils.isEmpty(baseExpression)) {

                                 resolverConfig.setBaseXPathExpression(baseExpression);

                         }

                         NodeList qualifiers = (NodeList)xPath.evaluate("//resolverConfig/qualifier", new InputSource(new StringReader(xmlConfig)), XPathConstants.NODESET);

                         if (qualifiers == null || qualifiers.getLength() == 0) {

                                 throw new RiceRuntimeException("Invalid qualifier resolver configuration.  Must contain at least one qualifier!");

                         }

                         for (int index = 0; index < qualifiers.getLength(); index++) {

                                 Element qualifierElement = (Element)qualifiers.item(index);

                                 String name = qualifierElement.getAttribute("name");

                                 NodeList expressions = qualifierElement.getElementsByTagName("xPathExpression");

                                 if (expressions.getLength() != 1) {

                                         throw new RiceRuntimeException("There should only be a single xPathExpression per qualifier");

                                 }

                                 Element expressionElement = (Element)expressions.item(0);

                                 resolverConfig.getExpressionMap().put(name, expressionElement.getTextContent());

                         }

                         if (LOG.isDebugEnabled()) {

                                 LOG.debug("Using Resolver Config Settings: " + resolverConfig.toString());

                         }

                         return resolverConfig;

                 } catch (XPathExpressionException e) {

                         throw new RiceRuntimeException("Encountered an error parsing resolver config.", e);

                 }

         }

         class ResolverConfig {

                 private String baseXPathExpression = "/";

                 private Map<String, String> expressionMap = new HashMap<String, String>();

                 public String getBaseXPathExpression() {

                         return this.baseXPathExpression;

                 }

                 public void setBaseXPathExpression(String baseXPathExpression) {

                         this.baseXPathExpression = baseXPathExpression;

                 }

                 public Map<String, String> getExpressionMap() {

                         return this.expressionMap;

                 }

                 public void setExpressionMap(Map<String, String> expressionMap) {

                         this.expressionMap = expressionMap;

                 }

                 @Override

                 public String toString() {

                         StringBuffer sb = new StringBuffer();

                         sb.append(  '\n' );

                         sb.append("ResolverConfig Parameters\n");

                         sb.append( "      baseXPathExpression: " + baseXPathExpression + "\n" );

                         sb.append( "      expressionMap:\n" );

                         for (Map.Entry<String, String> entry : expressionMap.entrySet()) {

                                 sb.append( "            " + entry.getKey() + ": " + entry.getValue() + "\n" );

                         }

                         return sb.toString();

                 }

         }

 }