/**

  * 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.core.api.util.xml;

 import org.apache.commons.lang.StringUtils;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.jdom.Document;

 import org.jdom.Element;

 import org.jdom.JDOMException;

 import org.jdom.Namespace;

 import org.jdom.input.DOMBuilder;

 import org.jdom.input.SAXBuilder;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 import org.xml.sax.InputSource;

 import org.xml.sax.SAXException;

 import javax.xml.parsers.DocumentBuilder;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.transform.OutputKeys;

 import javax.xml.transform.Source;

 import javax.xml.transform.Transformer;

 import javax.xml.transform.TransformerException;

 import javax.xml.transform.TransformerFactory;

 import javax.xml.transform.dom.DOMResult;

 import javax.xml.transform.stream.StreamSource;

 import javax.xml.xpath.XPath;

 import javax.xml.xpath.XPathConstants;

 import javax.xml.xpath.XPathExpressionException;

 import java.io.BufferedReader;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.Reader;

 import java.io.StringReader;

 import java.lang.reflect.Method;

 import java.util.ArrayList;

 import java.util.Collection;

 /**

  * Provides a set of utilities for XML-related operations on org.jdom & org.w3c

  * xml Objects.

  *

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

  */

 public final class XmlHelper {

     private static final Log LOG = LogFactory.getLog(XmlHelper.class);

     private XmlHelper() {

         throw new UnsupportedOperationException("do not call");

     }

     /**

      * Creates jdom Document from a Reader.  Does not close the reader.

      *

      * @param xmlStream the reader representing the xmlstream

      * @return jdom document

      */

     public static org.jdom.Document buildJDocument(Reader xmlStream) {

         // use SAX Builder

         // don't verify for speed reasons

         final SAXBuilder builder = new SAXBuilder(false);

         try {

             return builder.build(xmlStream);

         } catch (IOException e) {

             throw new XmlException("Invalid xml string. ", e);

         } catch (JDOMException e) {

             throw new XmlException("Invalid xml string. ", e);

         }

     }

     /**

      * Creates jdom Document from a w3c Document.  Does not close the reader.

      *

      * @param document the w3c document

      * @return jdom document

      */

     public static org.jdom.Document buildJDocument(org.w3c.dom.Document document) {

         return new DOMBuilder().build(document);

     }

     /**

      * Find all Elements in document of a particular name

      *

      * @param root the starting Element to scan

      * @param elementName name of the Element to scan for

      * @return collection of the Elements found.

      *         returns an empty collection if none are found.

      */

     public static Collection<Element> findElements(Element root, String elementName) {

         Collection<Element> elementList = new ArrayList<Element>();

         if (root == null) {

             return elementList;

         }

         XmlHelper.findElements(root, elementName, elementList);

         return elementList;

     }

     public static void appendXml(Node parentNode, String xml) throws SAXException, IOException, ParserConfigurationException {

         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

         factory.setValidating(false);

         org.w3c.dom.Document xmlDocument = factory.newDocumentBuilder().parse(new InputSource(new StringReader(xml)));

         org.w3c.dom.Element xmlDocumentElement = xmlDocument.getDocumentElement();

         Node importedNode = parentNode.getOwnerDocument().importNode(xmlDocumentElement, true);

         parentNode.appendChild(importedNode);

     }

     public static org.w3c.dom.Document readXml(String xml) throws TransformerException {

         Source source = new StreamSource(new BufferedReader(new StringReader(xml)));

         DOMResult result = new DOMResult();

         Transformer transformer = TransformerFactory.newInstance().newTransformer();

         transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

         transformer.transform(source, result);

         return (org.w3c.dom.Document) result.getNode();

     }

     public static void propagateNamespace(Element element, Namespace namespace) {

         element.setNamespace(namespace);

         for (Object childElement : element.getChildren()) {

             propagateNamespace((Element) childElement, namespace);

         }

     }

     public static org.w3c.dom.Document trimXml(InputStream input) throws SAXException, IOException, ParserConfigurationException {

         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

         factory.setIgnoringElementContentWhitespace(true);

         DocumentBuilder builder = factory.newDocumentBuilder();

         org.w3c.dom.Document oldDocument = builder.parse(input);

         org.w3c.dom.Element naviElement = oldDocument.getDocumentElement();

         trimElement(naviElement);

         return oldDocument;

     }

     public static Document trimSAXXml(InputStream input) throws JDOMException, SAXException, IOException, ParserConfigurationException {

         SAXBuilder builder = new SAXBuilder(false);

         Document oldDocument = builder.build(input);

         Element naviElement = oldDocument.getRootElement();

         trimSAXElement(naviElement);

         return oldDocument;

     }

     /**

      * Convenience method that performs an xpath evaluation to determine whether the expression

      * evaluates to true (a node exists).

      * This is method exists only to disambiguate the cases of determining the *presence* of a node

      * and determining the *boolean value of the node as converted from a string*, as the syntaxes

      * are very similar and could be misleading.

      *

      * @param xpath      the XPath object

      * @param expression the XPath expression

      * @param object     the object on which to evaluate the expression as required by the XPath API, typically a Node

      * @return whether the result of the expression evaluation, which is whether or not a node was present

      * @throws XPathExpressionException if the expression fails

      */

     public static boolean pathExists(XPath xpath, String expression, Object object) throws XPathExpressionException {

         return ((Boolean) xpath.evaluate(expression, object, XPathConstants.BOOLEAN)).booleanValue();

     }

     public static org.w3c.dom.Element propertiesToXml(org.w3c.dom.Document doc, Object o, String elementName) throws Exception {

         Class<?> c = o.getClass();

         org.w3c.dom.Element wrapper = doc.createElement(elementName);

         Method[] methods = c.getMethods();

         for (Method method : methods) {

             String name = method.getName();

             if ("getClass".equals(name)) {

                 continue;

             }

             if (!name.startsWith("get") || method.getParameterTypes().length > 0) {

                 continue;

             }

             name = name.substring("get".length());

             name = StringUtils.uncapitalize(name);

             try {

                 Object result = method.invoke(o);

                 final String value;

                 if (result == null) {

                     LOG.debug("value of " + name + " method on object " + o.getClass() + " is null");

                     value = "";

                 } else {

                     value = result.toString();

                 }

                 org.w3c.dom.Element fieldE = doc.createElement(name);

                 fieldE.appendChild(doc.createTextNode(value));

                 wrapper.appendChild(fieldE);

             } catch (Exception e) {

                 throw new XmlException("Error accessing method '" + method.getName() + "' of instance of " + c, e);

             }

         }

         return wrapper;

     }

     /**

      * This function is tail-recursive and just adds the root to the list if it

      * matches and checks the children.

      *

      * @param root the root element to search under

      * @param elementName the element name to find

      * @param list a list of found element

      */

     private static void findElements(Element root, String elementName, Collection<Element> list) {

         if (root != null) {

             if (root.getName().equals(elementName)) {

                 list.add(root);

             }

             for (Object item : root.getChildren()) {

                 if (item != null) {

                     XmlHelper.findElements((Element) item, elementName, list);

                 }

             }

         }

     }

     private static void trimElement(Node node) throws SAXException, IOException, ParserConfigurationException {

         if (node.hasChildNodes()) {

             NodeList children = node.getChildNodes();

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

                 Node child = children.item(i);

                 if (child != null) {

                     trimElement(child);

                 }

             }

         } else {

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

                 String text = node.getNodeValue();

                 text = StringUtils.isEmpty(text) ? "" : text.trim();

                 node.setNodeValue(text);

             }

         }

     }

     private static void trimSAXElement(Element element) throws SAXException, IOException, ParserConfigurationException {

         if (!element.getChildren().isEmpty()) {

             for (Object child : element.getChildren()) {

                 if (child != null) {

                     trimSAXElement((Element) child);

                 }

             }

         } else {

             String text = element.getTextTrim();

             if (StringUtils.isEmpty(text)) {

                 text = "";

             }

             element.setText(text);

         }

     }

 }