/*
    * EL4J, the Extension Library for the J2EE, adds incremental enhancements to
    * the spring framework, http://el4j.sf.net
    * Copyright (C) 2006 by ELCA Informatique SA, Av. de la Harpe 22-24,
    * 1000 Lausanne, Switzerland, http://www.elca.ch
    *
    * EL4J is published under the GNU Lesser General Public License (LGPL)
    * Version 2.1. See http://www.gnu.org/licenses/
    *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   * GNU Lesser General Public License for more details.
   *
   * For alternative licensing, please contact info@elca.ch
   */
  package ch.elca.el4j.services.xmlmerge.action;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.Reader;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Hashtable;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.jdom.Element;
  import org.xml.sax.EntityResolver;
  import org.xml.sax.InputSource;
  import org.xml.sax.SAXException;
  
  import com.wutka.dtd.DTD;
  import com.wutka.dtd.DTDAny;
  import com.wutka.dtd.DTDContainer;
  import com.wutka.dtd.DTDElement;
  import com.wutka.dtd.DTDItem;
  import com.wutka.dtd.DTDName;
  import com.wutka.dtd.DTDParser;
  
  import ch.elca.el4j.services.xmlmerge.AbstractXmlMergeException;
  import ch.elca.el4j.services.xmlmerge.Action;
  import ch.elca.el4j.services.xmlmerge.DocumentException;
  import ch.elca.el4j.services.xmlmerge.ElementException;
  import ch.elca.el4j.services.xmlmerge.XmlMergeContext;
  
  /**
   * Copy the patch element in the output parent with the correct position
   * according to the DTD declared in doctype.
   *
   * @svnLink $Revision: 3874 $;$Date: 2009-08-04 14:25:40 +0200 (Di, 04. Aug 2009) $;$Author: swismer $;$URL: https://el4j.svn.sourceforge.net/svnroot/el4j/branches/el4j_3_1/el4j/framework/modules/xml_merge/common/src/main/java/ch/elca/el4j/services/xmlmerge/action/DtdInsertAction.java $
   *
   * @author Laurent Bovet (LBO)
   * @author Alex Mathey (AMA)
   */
  public class DtdInsertAction implements Action {
  
  	/**
  	 * Map containing (ID, DTD) pairs, where ID represents the system ID of a
  	 * DTD, and DTD represents the corresponding DTD.
  	 */
  	static Map s_dtdMap = new Hashtable();
  	
  	/**
  	 * Private logger.
  	 */
  	private static Logger s_logger
  		= LoggerFactory.getLogger(DtdInsertAction.class);
  		
  	/**
  	 * {@inheritDoc}
  	 */
  	public void perform(Element originalElement, Element patchElement,
  		Element outputParentElement) throws AbstractXmlMergeException {
  
  		Element element;
  
  		if (originalElement != null) {
  			element = (Element) originalElement.clone();
  		} else {
  			element = (Element) patchElement.clone();
  		}
  
  		DTD dtd = getDTD(outputParentElement);
  
  		List dtdElements = dtd.getItemsByType(DTDElement.class);
  
  		// Find the corresponding element
  		DTDElement parentDtdElement = null;
  		for (Iterator it = dtdElements.iterator(); it.hasNext();) {
  			DTDElement dtdElement = (DTDElement) it.next();
  
  			if (dtdElement.getName().equals(outputParentElement.getName())) {
  				parentDtdElement = dtdElement;
 			}
 		}
 
 		if (parentDtdElement == null) {
 			throw new ElementException(element, "Element "
 				+ outputParentElement.getName() + " not defined in DTD");
 		} else {
 
 			DTDItem item = parentDtdElement.getContent();
 
 			if (item instanceof DTDAny) {
 				// the parent element accepts anything in any order
 				outputParentElement.addContent(element);
 			} else if (item instanceof DTDContainer) {
 
 				// List existing elements in output parent element
 				List existingChildren = outputParentElement.getChildren();
 
 				if (existingChildren.size() == 0) {
 					// This is the first child
 					outputParentElement.addContent(element);
 				} else {
 
 					List orderedDtdElements = getOrderedDtdElements(
 						(DTDContainer) item);
 
 					int indexOfNewElementInDtd = orderedDtdElements
 						.indexOf(element.getName());
 					s_logger.debug("index of element " + element.getName()
 						+ ": " + indexOfNewElementInDtd);
 
 					int pos = existingChildren.size();
 
 					// Calculate the position in the parent where we insert the
 					// element
 					for (int i = 0; i < existingChildren.size(); i++) {
 						String elementName = ((Element) existingChildren.get(i))
 							.getName();
 						s_logger.debug("index of child " + elementName + ": "
 							+ orderedDtdElements.indexOf(elementName));
 						if (orderedDtdElements.indexOf(elementName)
 							> indexOfNewElementInDtd) {
 							pos = i;
 							break;
 						}
 					}
 
 					s_logger.debug("adding element " + element.getName()
 						+ " add in pos " + pos);
 					outputParentElement.addContent(pos, element);
 
 				}
 
 			}
 
 		}
 
 	}
 
 	/**
 	 * Gets the DTD declared in the doctype of the element's owning document.
 	 *
 	 * @param element
 	 *            The element for which the DTD will be retrieved
 	 * @return The DTD declared in the doctype of the element's owning document
 	 * @throws DocumentException
 	 *             If an error occurred during DTD retrieval
 	 */
 	public DTD getDTD(Element element) throws DocumentException {
 
 		if (element.getDocument().getDocType() != null) {
 
 			String systemId = element.getDocument().getDocType().getSystemID();
 
 			DTD dtd = (DTD) s_dtdMap.get(systemId);
 
 			// if not in cache, create the DTD and put it in cache
 			if (dtd == null) {
 				Reader reader =null;
 				
 				// first try the configured EntityResolver
 				EntityResolver er= XmlMergeContext.getEntityResolver();
 				if (er != null) {
 					InputSource is = null;
 					try {
 						is = er.resolveEntity("", systemId);
 					} catch (SAXException e) {
 						// ignore deliberately
 					} catch (IOException e) {
 						// ignore deliberately
 					}
 					if (is != null) {
 						// there can be either a Reader or an Input stream in is
 						
 						reader = is.getCharacterStream();
 						if (reader == null) {
 							InputStream inputstream = is.getByteStream();
 							if (inputstream != null) {
 								reader = new InputStreamReader(inputstream);
 							}
 						}
 					}
 				}
 				
 				if (reader == null) {
 					// lookup URL of DTD
 					URL url;
 					try {
 						url = new URL(systemId);
 						reader = new InputStreamReader(url.openStream());
 					} catch (MalformedURLException e) {
 						throw new DocumentException(element.getDocument(), e);
 					} catch (IOException ioe) {
 						throw new DocumentException(element.getDocument(), ioe);
 					}
 				}
 				
 				try {
 					dtd = new DTDParser(reader).parse();
 				} catch (IOException ioe) {
 					throw new DocumentException(element.getDocument(), ioe);
 				}
 
 				s_dtdMap.put(systemId, dtd);
 			}
 
 			return dtd;
 
 		} else {
 			throw new DocumentException(element.getDocument(),
 				"No DTD specified in document " + element.getDocument());
 		}
 	}
 
 	/**
 	 * Retieves a list containing the DTD elements of a given DTD container.
 	 * @param container A DTD container.
 	 * @return A list containing the DTD elements of a given DTD container
 	 */
 	public List getOrderedDtdElements(DTDContainer container) {
 		List result = new ArrayList();
 
 		DTDItem[] items = container.getItems();
 
 		for (int i = 0; i < items.length; i++) {
 			if (items[i] instanceof DTDContainer) {
 				// recursively add container children
 				result.addAll(getOrderedDtdElements((DTDContainer) items[i]));
 			} else if (items[i] instanceof DTDName) {
 				result.add(((DTDName) items[i]).getValue());
 			}
 		}
 
 		return result;
 
 	}
 
 }