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);

         }

     }

 }