/*
    * 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.merge;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  
  import org.jdom.DocType;
  import org.jdom.Document;
  import org.jdom.Element;
  import org.jdom.JDOMException;
  import org.jdom.input.DOMBuilder;
  import org.jdom.input.SAXBuilder;
  import org.jdom.output.DOMOutputter;
  import org.jdom.output.Format;
  import org.jdom.output.XMLOutputter;
  import org.xml.sax.EntityResolver;
  
  import ch.elca.el4j.services.xmlmerge.AbstractXmlMergeException;
  import ch.elca.el4j.services.xmlmerge.DocumentException;
  import ch.elca.el4j.services.xmlmerge.Mapper;
  import ch.elca.el4j.services.xmlmerge.Matcher;
  import ch.elca.el4j.services.xmlmerge.MergeAction;
  import ch.elca.el4j.services.xmlmerge.ParseException;
  import ch.elca.el4j.services.xmlmerge.XmlMerge;
  import ch.elca.el4j.services.xmlmerge.XmlMergeContext;
  import ch.elca.el4j.services.xmlmerge.action.OrderedMergeAction;
  import ch.elca.el4j.services.xmlmerge.factory.StaticOperationFactory;
  import ch.elca.el4j.services.xmlmerge.mapper.IdentityMapper;
  import ch.elca.el4j.services.xmlmerge.matcher.TagMatcher;
  
  // Checkstyle: MagicNumber off
  
  /**
   * Default implementation of XmlMerge. Create all JDOM documents, then perform
   * the merge into a new JDOM document.
   *
   * @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/merge/DefaultXmlMerge.java $
   *
   * @author Laurent Bovet (LBO)
   * @author Alex Mathey (AMA)
   */
  public class DefaultXmlMerge implements XmlMerge {
  
  	/**
  	 * Root merge action.
  	 */
  	private MergeAction m_rootMergeAction = new OrderedMergeAction();
  
  	/**
  	 * Root matcher.
  	 */
  	private Matcher m_rootMatcher = new TagMatcher();
  
  	
  	/**
  	 * Creates a new DefaultXmlMerge instance.
  	 */
  	public DefaultXmlMerge() {
  		m_rootMergeAction.setActionFactory(new StaticOperationFactory(
  			new OrderedMergeAction()));
  		m_rootMergeAction.setMapperFactory(new StaticOperationFactory(
  			new IdentityMapper()));
  		m_rootMergeAction.setMatcherFactory(new StaticOperationFactory(
  			new TagMatcher()));
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public void setRootMapper(Mapper rootMapper) { }
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public void setRootMergeAction(MergeAction rootMergeAction) {
  		this.m_rootMergeAction = rootMergeAction;
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public String merge(String[] sources) throws AbstractXmlMergeException {
 
 		InputStream[] inputStreams = new InputStream[sources.length];
 
 		for (int i = 0; i < sources.length; i++) {
 			inputStreams[i] = new ByteArrayInputStream(sources[i].getBytes());
 		}
 
 		InputStream merged = merge(inputStreams);
 
 		ByteArrayOutputStream result = new ByteArrayOutputStream();
 
 		try {
 			byte[] buffer = new byte[1024];
 			int len;
 			while ((len = merged.read(buffer)) != -1) {
 				result.write(buffer, 0, len);
 			}
 		} catch (IOException ioe) {
 			// should never happen
 			throw new RuntimeException(ioe);
 		}
 
 		return result.toString();
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public org.w3c.dom.Document merge(org.w3c.dom.Document[] sources)
 		throws AbstractXmlMergeException {
 		DOMBuilder domb = new DOMBuilder();
 
 		// to save all XML files as JDOM objects
 		Document[] docs = new Document[sources.length];
 
 		for (int i = 0; i < sources.length; i++) {
 			// ask JDOM to parse the given inputStream
 			docs[i] = domb.build(sources[i]);
 		}
 
 		Document result = doMerge(docs);
 
 		DOMOutputter outputter = new DOMOutputter();
 
 		try {
 			return outputter.output(result);
 		} catch (JDOMException e) {
 			throw new DocumentException(result, e);
 		}
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public InputStream merge(InputStream[] sources)
 		throws AbstractXmlMergeException {
 		SAXBuilder sxb = new SAXBuilder();
 
 		EntityResolver entityResolver = XmlMergeContext.getEntityResolver();
 		if (entityResolver != null) {
 			sxb.setEntityResolver(entityResolver);
 		}
 		
 		// to save all XML files as JDOM objects
 		Document[] docs = new Document[sources.length];
 
 		for (int i = 0; i < sources.length; i++) {
 			try {
 				// ask JDOM to parse the given inputStream
 				docs[i] = sxb.build(sources[i]);
 			} catch (JDOMException e) {
 				throw new ParseException(e);
 			} catch (IOException ioe) {
 				ioe.printStackTrace();
 				throw new ParseException(ioe);
 			}
 		}
 
 		Document result = doMerge(docs);
 
 		Format prettyFormatter = Format.getPrettyFormat();
 		// Use system line seperator to avoid problems
 		// with carriage return under linux
 		prettyFormatter.setLineSeparator(System.getProperty("line.separator"));
 		XMLOutputter sortie = new XMLOutputter(prettyFormatter);
 		
 		ByteArrayOutputStream buffer = new ByteArrayOutputStream();
 
 		try {
 			sortie.output(result, buffer);
 		} catch (IOException ex) {
 			throw new DocumentException(result, ex);
 		}
 
 		return new ByteArrayInputStream(buffer.toByteArray());
 	}
 
 	/**
 	 * Performs the actual merge.
 	 *
 	 * @param docs
 	 *            The documents to merge
 	 * @return The merged result document
 	 * @throws AbstractXmlMergeException
 	 *             If an error occurred during the merge
 	 */
 	private Document doMerge(Document[] docs) throws AbstractXmlMergeException {
 		Document temporary = docs[0];
 
 		for (int i = 1; i < docs.length; i++) {
 
 			if (!m_rootMatcher.matches(temporary.getRootElement(), docs[i]
 				.getRootElement())) {
 				throw new IllegalArgumentException(
 					"Root elements do not match.");
 			}
 
 			Document output = new Document();
 			if (docs[0].getDocType() != null) {
 				output.setDocType((DocType) docs[0].getDocType().clone());
 			}
 			output.setRootElement(new Element("root"));
 
 			m_rootMergeAction.perform(temporary.getRootElement(), docs[i]
 				.getRootElement(), output.getRootElement());
 
 			Element root = (Element) output.getRootElement().getChildren().get(
 				0);
 			root.detach();
 
 			temporary.setRootElement(root);
 		}
 
 		return temporary;
 	}
 
 }
 
 // Checkstyle: MagicNumber on