/*

  * 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.

  */

 package org.apache.commons.configuration;

 import java.io.File;

 import java.io.PrintWriter;

 import java.io.Reader;

 import java.io.Writer;

 import java.net.URL;

 import java.util.Iterator;

 import java.util.List;

 import javax.xml.parsers.SAXParser;

 import javax.xml.parsers.SAXParserFactory;

 import org.apache.commons.lang.StringEscapeUtils;

 import org.apache.commons.lang.StringUtils;

 import org.xml.sax.Attributes;

 import org.xml.sax.EntityResolver;

 import org.xml.sax.InputSource;

 import org.xml.sax.XMLReader;

 import org.xml.sax.helpers.DefaultHandler;

 /**

  * This configuration implements the XML properties format introduced in Java

  * 5.0, see http://java.sun.com/j2se/1.5.0/docs/api/java/util/Properties.html.

  * An XML properties file looks like this:

  *

  * <pre>

  * <?xml version="1.0"?>

  * <!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">

  * <properties>

  *   <comment>Description of the property list</comment>

  *   <entry key="key1">value1</entry>

  *   <entry key="key2">value2</entry>

  *   <entry key="key3">value3</entry>

  * </properties>

  * </pre>

  *

  * The Java 5.0 runtime is not required to use this class. The default encoding

  * for this configuration format is UTF-8. Note that unlike

  * {@code PropertiesConfiguration}, {@code XMLPropertiesConfiguration}

  * does not support includes.

  *

  * <em>Note:</em>Configuration objects of this type can be read concurrently

  * by multiple threads. However if one of these threads modifies the object,

  * synchronization has to be performed manually.

  *

  * @author Emmanuel Bourg

  * @author Alistair Young

  * @version $Id: XMLPropertiesConfiguration.java 1210207 2011-12-04 20:43:50Z oheger $

  * @since 1.1

  */

 public class XMLPropertiesConfiguration extends PropertiesConfiguration

 {

     /**

      * The default encoding (UTF-8 as specified by http://java.sun.com/j2se/1.5.0/docs/api/java/util/Properties.html)

      */

     private static final String DEFAULT_ENCODING = "UTF-8";

     // initialization block to set the encoding before loading the file in the constructors

     {

         setEncoding(DEFAULT_ENCODING);

     }

     /**

      * Creates an empty XMLPropertyConfiguration object which can be

      * used to synthesize a new Properties file by adding values and

      * then saving(). An object constructed by this C'tor can not be

      * tickled into loading included files because it cannot supply a

      * base for relative includes.

      */

     public XMLPropertiesConfiguration()

     {

         super();

     }

     /**

      * Creates and loads the xml properties from the specified file.

      * The specified file can contain "include" properties which then

      * are loaded and merged into the properties.

      *

      * @param fileName The name of the properties file to load.

      * @throws ConfigurationException Error while loading the properties file

      */

     public XMLPropertiesConfiguration(String fileName) throws ConfigurationException

     {

         super(fileName);

     }

     /**

      * Creates and loads the xml properties from the specified file.

      * The specified file can contain "include" properties which then

      * are loaded and merged into the properties.

      *

      * @param file The properties file to load.

      * @throws ConfigurationException Error while loading the properties file

      */

     public XMLPropertiesConfiguration(File file) throws ConfigurationException

     {

         super(file);

     }

     /**

      * Creates and loads the xml properties from the specified URL.

      * The specified file can contain "include" properties which then

      * are loaded and merged into the properties.

      *

      * @param url The location of the properties file to load.

      * @throws ConfigurationException Error while loading the properties file

      */

     public XMLPropertiesConfiguration(URL url) throws ConfigurationException

     {

         super(url);

     }

     @Override

     public void load(Reader in) throws ConfigurationException

     {

         SAXParserFactory factory = SAXParserFactory.newInstance();

         factory.setNamespaceAware(false);

         factory.setValidating(true);

         try

         {

             SAXParser parser = factory.newSAXParser();

             XMLReader xmlReader = parser.getXMLReader();

             xmlReader.setEntityResolver(new EntityResolver()

             {

                 public InputSource resolveEntity(String publicId, String systemId)

                 {

                     return new InputSource(getClass().getClassLoader().getResourceAsStream("properties.dtd"));

                 }

             });

             xmlReader.setContentHandler(new XMLPropertiesHandler());

             xmlReader.parse(new InputSource(in));

         }

         catch (Exception e)

         {

             throw new ConfigurationException("Unable to parse the configuration file", e);

         }

         // todo: support included properties ?

     }

     @Override

     public void save(Writer out) throws ConfigurationException

     {

         PrintWriter writer = new PrintWriter(out);

         String encoding = getEncoding() != null ? getEncoding() : DEFAULT_ENCODING;

         writer.println("<?xml version=\"1.0\" encoding=\"" + encoding + "\"?>");

         writer.println("<!DOCTYPE properties SYSTEM \"http://java.sun.com/dtd/properties.dtd\">");

         writer.println("<properties>");

         if (getHeader() != null)

         {

             writer.println("  <comment>" + StringEscapeUtils.escapeXml(getHeader()) + "</comment>");

         }

         Iterator<String> keys = getKeys();

         while (keys.hasNext())

         {

             String key = keys.next();

             Object value = getProperty(key);

             if (value instanceof List)

             {

                 writeProperty(writer, key, (List<?>) value);

             }

             else

             {

                 writeProperty(writer, key, value);

             }

         }

         writer.println("</properties>");

         writer.flush();

     }

     /**

      * Write a property.

      *

      * @param out the output stream

      * @param key the key of the property

      * @param value the value of the property

      */

     private void writeProperty(PrintWriter out, String key, Object value)

     {

         // escape the key

         String k = StringEscapeUtils.escapeXml(key);

         if (value != null)

         {

             // escape the value

             String v = StringEscapeUtils.escapeXml(String.valueOf(value));

             v = StringUtils.replace(v, String.valueOf(getListDelimiter()), "\\" + getListDelimiter());

             out.println("  <entry key=\"" + k + "\">" + v + "</entry>");

         }

         else

         {

             out.println("  <entry key=\"" + k + "\"/>");

         }

     }

     /**

      * Write a list property.

      *

      * @param out the output stream

      * @param key the key of the property

      * @param values a list with all property values

      */

     private void writeProperty(PrintWriter out, String key, List<?> values)

     {

         for (Object value : values)

         {

             writeProperty(out, key, value);

         }

     }

     /**

      * SAX Handler to parse a XML properties file.

      *

      * @author Alistair Young

      * @since 1.2

      */

     private class XMLPropertiesHandler extends DefaultHandler

     {

         /** The key of the current entry being parsed. */

         private String key;

         /** The value of the current entry being parsed. */

         private StringBuilder value = new StringBuilder();

         /** Indicates that a comment is being parsed. */

         private boolean inCommentElement;

         /** Indicates that an entry is being parsed. */

         private boolean inEntryElement;

         @Override

         public void startElement(String uri, String localName, String qName, Attributes attrs)

         {

             if ("comment".equals(qName))

             {

                 inCommentElement = true;

             }

             if ("entry".equals(qName))

             {

                 key = attrs.getValue("key");

                 inEntryElement = true;

             }

         }

         @Override

         public void endElement(String uri, String localName, String qName)

         {

             if (inCommentElement)

             {

                 // We've just finished a <comment> element so set the header

                 setHeader(value.toString());

                 inCommentElement = false;

             }

             if (inEntryElement)

             {

                 // We've just finished an <entry> element, so add the key/value pair

                 addProperty(key, value.toString());

                 inEntryElement = false;

             }

             // Clear the element value buffer

             value = new StringBuilder();

         }

         @Override

         public void characters(char[] chars, int start, int length)

         {

             /**

              * We're currently processing an element. All character data from now until

              * the next endElement() call will be the data for this  element.

              */

             value.append(chars, start, length);

         }

     }

 }