/*
    * Copyright 2008-2013 smartics, Kronseder & Reiner GmbH
    *
    * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
    *
   * 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 de.smartics.maven.issues.notes;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.StringWriter;
  
  import javax.xml.parsers.DocumentBuilder;
  import javax.xml.parsers.DocumentBuilderFactory;
  import javax.xml.parsers.ParserConfigurationException;
  import javax.xml.transform.OutputKeys;
  import javax.xml.transform.Transformer;
  import javax.xml.transform.TransformerConfigurationException;
  import javax.xml.transform.TransformerException;
  import javax.xml.transform.TransformerFactory;
  import javax.xml.transform.dom.DOMSource;
  import javax.xml.transform.stream.StreamResult;
  
  import org.w3c.dom.Document;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  import org.xml.sax.SAXException;
  
  /**
   * The reader to read manual release notes to include in the report.
   *
   * @author <a href="mailto:robert.reiner@smartics.de">Robert Reiner</a>
   * @version $Revision:591 $
   */
  public class NotesReader
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    // --- members --------------------------------------------------------------
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    /**
     * Default constructor.
     */
    public NotesReader()
    {
    }
  
    // ****************************** Inner Classes *****************************
  
    // ********************************* Methods ********************************
  
    // --- init -----------------------------------------------------------------
  
    // --- get&set --------------------------------------------------------------
  
    // --- business -------------------------------------------------------------
  
    /**
     * Reads the document from the input stream and returns the content of the
     * body element.
     *
     * @param inputStream the stream to read from.
     * @return the content of the body element.
     * @throws IOException if the body content cannot be extracted.
     */
    public String read(final InputStream inputStream) throws IOException
    {
      final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
      DocumentBuilder builder = null;
      try
      {
        builder = factory.newDocumentBuilder();
        final Document document = builder.parse(inputStream);
        return extractBodyContent(document);
      }
      catch (final ParserConfigurationException e)
      {
        final IOException ex =
            new IOException(
                "Cannot create parser to read description file from stream.");
        ex.initCause(e);
        throw ex; // NOPMD Original stack trace is preserved.
      }
      catch (final SAXException e)
     {
       final IOException ex =
           new IOException("Cannot read description file from stream.");
       ex.initCause(e);
       throw ex; // NOPMD Original stack trace is preserved.
     }
   }
 
   /**
    * Extracts the body content from the document.
    *
    * @param document the complete document to extract the content of the body
    *          element.
    * @return the content of the body element as a string.
    * @throws IOException if there is more or less than one body element or there
    *           are problems processing the document.
    */
   private String extractBodyContent(final Document document) throws IOException
   {
     final NodeList bodyList = document.getElementsByTagName("body");
     final int bodyCount = bodyList.getLength();
     if (bodyCount != 1)
     {
       throw new IOException("Expected one body element, found " + bodyCount
                             + '.');
     }
 
     final Node body = bodyList.item(0);
 
     return extractContent(body);
   }
 
   /**
    * Extracts the content of the body element, removing the body tags.
    *
    * @param body the node whose content is requested.
    * @return the content of the body element.
    * @throws IOException if there is a problem processing the node.
    */
   private String extractContent(final Node body) throws IOException
   {
     try
     {
       final DOMSource source = new DOMSource(body);
       final StringWriter writer = new StringWriter(2048);
       final StreamResult result = new StreamResult(writer);
       final TransformerFactory transformerFactory =
           TransformerFactory.newInstance();
       final Transformer transformer = transformerFactory.newTransformer();
       // transformer.setOutputProperty(OutputKeys.INDENT, "yes");
       transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
       transformer.transform(source, result);
 
       final String content = writer.toString();
       final int start = content.indexOf("<body>") + "<body>".length();
       final int end = content.lastIndexOf("</body>");
 
       return content.substring(start, end).trim();
     }
     catch (final TransformerConfigurationException e)
     {
       final IOException ex =
           new IOException("Cannot write description file to memory.");
       ex.initCause(e);
       throw ex; // NOPMD Original stack trace is preserved.
     }
     catch (final TransformerException e)
     {
       final IOException ex =
           new IOException("Cannot write description file to memory.");
       ex.initCause(e);
       throw ex; // NOPMD Original stack trace is preserved.
     }
   }
 
   // --- object basics --------------------------------------------------------
 
 }