/*

  * Copyright 2007-2009 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;

 import java.io.InputStream;

 import javax.xml.parsers.DocumentBuilder;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.transform.TransformerException;

 import javax.xml.xpath.XPath;

 import javax.xml.xpath.XPathConstants;

 import javax.xml.xpath.XPathExpressionException;

 import javax.xml.xpath.XPathFactory;

 import org.apache.log4j.Logger;

 import org.kuali.rice.kew.edl.bo.EDocLiteStyle;

 import org.kuali.rice.kew.edl.service.StyleService;

 import org.kuali.rice.kew.exception.WorkflowServiceErrorException;

 import org.kuali.rice.kew.exception.WorkflowServiceErrorImpl;

 import org.kuali.rice.kew.util.KEWConstants;

 import org.kuali.rice.kew.util.XmlHelper;

 import org.w3c.dom.Document;

 import org.w3c.dom.Element;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 /**

  * Parser for Style content type, managed by StyleService

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

  */

 public class StyleXmlParser {

         private static final Logger LOG = Logger.getLogger(StyleXmlParser.class);

     private static ThreadLocal DOCUMENT_BUILDER = new ThreadLocal() {

         protected Object initialValue() {

             try {

                 return DocumentBuilderFactory.newInstance().newDocumentBuilder();

             } catch (ParserConfigurationException pce) {

                 // well folks, there is not much we can do if we get a ParserConfigurationException

                 // so might as well isolate the evilness here, and just balk if this occurs

                 String message = "Error obtaining document builder";

                 LOG.error(message, pce);

                 return new RuntimeException(message, pce);

             }

         }

     };

     /**

      * Returns a valid DocumentBuilder

      * @return a valid DocumentBuilder

      */

     private static DocumentBuilder getDocumentBuilder() {

         return (DocumentBuilder) DOCUMENT_BUILDER.get();

     }

     public static void loadXml(StyleService styleService, InputStream inputStream, String principalId) {

         DocumentBuilder db = getDocumentBuilder();

         XPath xpath = XPathFactory.newInstance().newXPath();

         Document doc;

         // parse and save EDocLiteDefinition, EDocLiteStyle, or EDocLiteAssociation xml from to-be-determined XML format

         //try {

         try {

             doc = db.parse(inputStream);

         } catch (Exception e) {

             throw generateException("Error parsing Style XML file", e);

         }

             /*try {

                 LOG.info(XmlHelper.writeNode(doc.getFirstChild(), true));

             } catch (TransformerException e) {

                 LOG.warn("Error displaying document");

             }*/

             NodeList styles;

             try {

                 styles = (NodeList) xpath.evaluate("//" + XmlConstants.STYLE_STYLES, doc.getFirstChild(), XPathConstants.NODESET);

             } catch (XPathExpressionException e) {

                 throw generateException("Error evaluating XPath expression", e);

             }

             LOG.info("Styles: " + styles);

             for (int i = 0; i < styles.getLength(); i++) {

                 Node edl = styles.item(i);

                 NodeList children = edl.getChildNodes();

                 for (int j = 0; j < children.getLength(); j++) {

                     Node node = children.item(j);

                     if (node.getNodeType() == Node.ELEMENT_NODE) {

                         Element e = (Element) node;

                         if (XmlConstants.STYLE_STYLE.equals(node.getNodeName())) {

                             LOG.debug("Digesting style: " + e.getAttribute("name"));

                             EDocLiteStyle style = parseStyle(e);

                             styleService.saveStyle(style);

                         }

                     }

                 }

             }

         //} catch (Exception e) {

         //    throw generateException("Error parsing EDocLite XML file", e);

         //}

     }

     private static WorkflowServiceErrorException generateException(String error, Throwable cause) {

         WorkflowServiceErrorException wsee = new WorkflowServiceErrorException(error, new WorkflowServiceErrorImpl(error, KEWConstants.XML_FILE_PARSE_ERROR));

         if (cause != null) {

             wsee.initCause(cause);

         }

         return wsee;

     }

     /**

      * Parses an EDocLiteStyle

      *

      * @param e

      *            element to parse

      * @return an EDocLiteStyle

      */

     private static EDocLiteStyle parseStyle(Element e) {

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

         if (name == null || name.length() == 0) {

             throw generateMissingAttribException(XmlConstants.STYLE_STYLE, "name");

         }

         EDocLiteStyle style = new EDocLiteStyle();

         style.setName(name);

         Element stylesheet = null;

         NodeList children = e.getChildNodes();

         for (int i = 0; i < children.getLength(); i++) {

             Node child = children.item(i);

             /*

              * LOG.debug("NodeName: " + child.getNodeName()); LOG.debug("LocalName: " + child.getLocalName()); LOG.debug("Prefix: " + child.getPrefix()); LOG.debug("NS URI: " + child.getNamespaceURI());

              */

             if (child.getNodeType() == Node.ELEMENT_NODE && "xsl:stylesheet".equals(child.getNodeName())) {

                 stylesheet = (Element) child;

                 break;

             }

         }

         if (stylesheet == null) {

             throw generateMissingChildException(XmlConstants.STYLE_STYLE, "xsl:stylesheet");

         }

         try {

             style.setXmlContent(XmlHelper.writeNode(stylesheet, true));

         } catch (TransformerException te) {

             throw generateSerializationException(XmlConstants.STYLE_STYLE, te);

         }

         return style;

     }

     private static WorkflowServiceErrorException generateMissingAttribException(String element, String attrib) {

         return generateException("Style '" + element + "' element must contain a '" + attrib + "' attribute", null);

     }

     private static WorkflowServiceErrorException generateMissingChildException(String element, String child) {

         return generateException("Style '" + element + "' element must contain a '" + child + "' child element", null);

     }

     private static WorkflowServiceErrorException generateSerializationException(String element, TransformerException cause) {

         return generateException("Error serializing Style '" + element + "' element", cause);

     }

 }