package org.apache.maven.shared.utils.xml;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   */
  
  import org.apache.maven.shared.utils.io.IOUtil;
  import org.apache.maven.shared.utils.xml.pull.XmlPullParserException;
  
  import org.xml.sax.*;
  import org.xml.sax.helpers.DefaultHandler;
  
  import javax.annotation.Nonnull;
  import javax.annotation.WillClose;
  import java.io.*;
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * @author Kristian Rosenvold
   */
  public class Xpp3DomBuilder
  {
      private static final boolean DEFAULT_TRIM = true;
  
      public static Xpp3Dom build( @WillClose @Nonnull Reader reader )
          throws XmlPullParserException
      {
          return build( reader, DEFAULT_TRIM );
      }
  
      public static Xpp3Dom build( @WillClose InputStream is, @Nonnull String encoding )
          throws XmlPullParserException
      {
          return build( is, encoding, DEFAULT_TRIM );
      }
  
      public static Xpp3Dom build( @WillClose InputStream is, @Nonnull String encoding, boolean trim )
          throws XmlPullParserException
      {
          try {
              Reader reader = new InputStreamReader(is, encoding);
              return build( reader, trim);
          } catch (UnsupportedEncodingException e) {
              throw new RuntimeException(e);
          }
      }
  
      public static Xpp3Dom build( @WillClose Reader reader, boolean trim )
              throws XmlPullParserException
      {
          try
          {
              DocHandler docHandler = parseSax(new InputSource(reader), trim);
              return docHandler.result;
          }
          finally
          {
              IOUtil.close( reader );
          }
      }
  
      private static DocHandler parseSax(@Nonnull InputSource inputSource, boolean trim) throws XmlPullParserException {
  
          try {
              DocHandler ch = new DocHandler(trim);
              XMLReader parser = org.xml.sax.helpers.XMLReaderFactory.createXMLReader();
              parser.setContentHandler( ch);
              parser.parse(inputSource);
              return ch;
          } catch (IOException e){
              throw new XmlPullParserException(e);
          } catch (SAXException e) {
              throw new XmlPullParserException(e);
          }
      }
  
  
      private static class DocHandler extends DefaultHandler {
          private final List<Xpp3Dom> elemStack = new ArrayList<Xpp3Dom>();
          private final List<StringBuilder> values = new ArrayList<StringBuilder>();
  
          // Todo: Use these for something smart !
          private final List<SAXParseException> warnings = new ArrayList<SAXParseException>();
         private final List<SAXParseException> errors = new ArrayList<SAXParseException>();
         private final List<SAXParseException> fatals = new ArrayList<SAXParseException>();
 
 
         Xpp3Dom result = null;
 
         private final boolean trim;
 
         DocHandler(boolean trim) {
             this.trim = trim;
         }
 
         @Override
         public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
 
             Xpp3Dom child = new Xpp3Dom( localName );
 
             attachToParent(child);
             pushOnStack(child);
 
             // Todo: Detecting tags that close immediately seem to be impossible in sax ?
             // http://stackoverflow.com/questions/12968390/detecting-self-closing-tags-in-sax
             values.add( new StringBuilder() );
 
             int size = attributes.getLength();
             for ( int i = 0; i < size; i++ )
             {
                 child.setAttribute(attributes.getQName(i), attributes.getValue(i));
             }
         }
 
         private boolean pushOnStack(Xpp3Dom child) {
             return elemStack.add(child);
         }
 
         private void attachToParent(Xpp3Dom child) {
             int depth = elemStack.size();
             if ( depth > 0 )
             {
                 elemStack.get(depth - 1).addChild(child);
             }
         }
 
         @Override
         public void warning(SAXParseException e) throws SAXException {
             warnings.add(e);
         }
 
         @Override
         public void error(SAXParseException e) throws SAXException {
             errors.add(e);
         }
 
         @Override
         public void fatalError(SAXParseException e) throws SAXException {
             fatals.add(e);
         }
 
 
         private Xpp3Dom pop()
         {
             int depth = elemStack.size() - 1;
             return elemStack.remove( depth );
         }
 
         @Override
         public void endElement(String uri, String localName, String qName) throws SAXException {
             int depth = elemStack.size() - 1;
 
             Xpp3Dom finishedConfiguration = pop();
 
                 /* this Object could be null if it is a singleton tag */
             Object accumulatedValue = values.remove( depth );
 
             if ( finishedConfiguration.getChildCount() == 0 )
             {
                 if ( accumulatedValue == null )
                 {
                     finishedConfiguration.setValue( "" ); // null in xpp3dom, but we dont do that around here
                 }
                 else
                 {
                     finishedConfiguration.setValue( accumulatedValue.toString() );
                 }
             }
 
             if ( depth == 0 )
             {
                 result = finishedConfiguration;
             }
         }
 
         @Override
         public void characters(char[] ch, int start, int length) throws SAXException {
             String text = new String(ch, start, length);
             appendToTopValue(trim ? text.trim() : text);
         }
 
         private void appendToTopValue(String toAppend) {
             //noinspection MismatchedQueryAndUpdateOfStringBuilder
             StringBuilder stringBuilder = values.get(values.size() - 1);
             stringBuilder.append( toAppend);
         }
     }
 
 }