/*
    * Copyright 2006 the original author or authors.
    *
    * 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 org.springframework.oxm.xstream;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.OutputStream;
  import java.io.OutputStreamWriter;
  import java.io.Reader;
  import java.io.Writer;
  import java.util.Iterator;
  import java.util.Map;
  import javax.xml.stream.XMLEventReader;
  import javax.xml.stream.XMLEventWriter;
  import javax.xml.stream.XMLStreamException;
  import javax.xml.stream.XMLStreamReader;
  import javax.xml.stream.XMLStreamWriter;
  
  import com.thoughtworks.xstream.XStream;
  import com.thoughtworks.xstream.converters.Converter;
  import com.thoughtworks.xstream.converters.ConverterMatcher;
  import com.thoughtworks.xstream.converters.SingleValueConverter;
  import com.thoughtworks.xstream.io.HierarchicalStreamReader;
  import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
  import com.thoughtworks.xstream.io.xml.CompactWriter;
  import com.thoughtworks.xstream.io.xml.DomReader;
  import com.thoughtworks.xstream.io.xml.DomWriter;
  import com.thoughtworks.xstream.io.xml.QNameMap;
  import com.thoughtworks.xstream.io.xml.SaxWriter;
  import com.thoughtworks.xstream.io.xml.StaxReader;
  import com.thoughtworks.xstream.io.xml.StaxWriter;
  import com.thoughtworks.xstream.io.xml.XppReader;
  import org.springframework.beans.propertyeditors.ClassEditor;
  import org.springframework.oxm.AbstractMarshaller;
  import org.springframework.oxm.XmlMappingException;
  import org.springframework.util.ObjectUtils;
  import org.springframework.xml.stream.StaxEventContentHandler;
  import org.springframework.xml.stream.XmlEventStreamReader;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.Node;
  import org.xml.sax.ContentHandler;
  import org.xml.sax.InputSource;
  import org.xml.sax.XMLReader;
  import org.xml.sax.ext.LexicalHandler;
  
  /**
   * Implementation of the <code>Marshaller</code> interface for XStream. By default, XStream does not require any further
   * configuration, though class aliases can be used to have more control over the behavior of XStream.
   * <p/>
   * Due to XStream's API, it is required to set the encoding used for writing to outputstreams. It defaults to
   * <code>UTF-8</code>.
   * <p/>
   * <b>Note</b> that XStream is an XML serialization library, not a data binding library. Therefore, it has limited
   * namespace support. As such, it is rather unsuitable for usage within Web services.
   *
   * @author Peter Meijer
   * @author Arjen Poutsma
   * @see #setEncoding(String)
   * @see #DEFAULT_ENCODING
   * @see #setAliases(Map)
   * @see #setConverters(ConverterMatcher[])
   * @since 1.0.0
   */
  public class XStreamMarshaller extends AbstractMarshaller {
  
      /** The default encoding used for stream access. */
      public static final String DEFAULT_ENCODING = "UTF-8";
  
      private XStream xstream = new XStream();
  
      private String encoding;
  
      private Class[] supportedClasses;
  
      /**
       * Returns the encoding to be used for stream access. If this property is not set, the default encoding is used.
       *
       * @see #DEFAULT_ENCODING
       */
      public String getEncoding() {
          return encoding != null ? encoding : DEFAULT_ENCODING;
      }
  
     /**
      * Sets the encoding to be used for stream access. If this property is not set, the default encoding is used.
      *
      * @see #DEFAULT_ENCODING
      */
     public void setEncoding(String encoding) {
         this.encoding = encoding;
     }
 
     /** Returns the XStream instance used by this marshaller. */
     public XStream getXStream() {
         return xstream;
     }
 
     /**
      * Sets the XStream mode.
      *
      * @see XStream#XPATH_REFERENCES
      * @see XStream#ID_REFERENCES
      * @see XStream#NO_REFERENCES
      */
     public void setMode(int mode) {
         getXStream().setMode(mode);
     }
 
     /**
      * Sets the classes supported by this marshaller. If this property is empty (the default), all classes are
      * supported.
      *
      * @see #supports(Class)
      */
     public void setSupportedClasses(Class[] supportedClasses) {
         this.supportedClasses = supportedClasses;
     }
 
     /**
      * Sets the <code>Converters</code> or <code>SingleValueConverters</code> to be registered with the
      * <code>XStream</code> instance.
      *
      * @see Converter
      * @see SingleValueConverter
      */
     public void setConverters(ConverterMatcher[] converters) {
         for (int i = 0; i < converters.length; i++) {
             if (converters[i] instanceof Converter) {
                 getXStream().registerConverter((Converter) converters[i], i);
             }
             else if (converters[i] instanceof SingleValueConverter) {
                 getXStream().registerConverter((SingleValueConverter) converters[i], i);
             }
             else {
                 throw new IllegalArgumentException("Invalid ConverterMatcher [" + converters[i] + "]");
             }
         }
     }
 
     /**
      * Set a alias/type map, consisting of string aliases mapped to <code>Class</code> instances (or Strings to be
      * converted to <code>Class</code> instances).
      *
      * @see org.springframework.beans.propertyeditors.ClassEditor
      */
     public void setAliases(Map aliases) {
         for (Iterator iterator = aliases.entrySet().iterator(); iterator.hasNext();) {
             Map.Entry entry = (Map.Entry) iterator.next();
             // Check whether we need to convert from String to Class.
             Class type;
             if (entry.getValue() instanceof Class) {
                 type = (Class) entry.getValue();
             }
             else {
                 ClassEditor editor = new ClassEditor();
                 editor.setAsText(String.valueOf(entry.getValue()));
                 type = (Class) editor.getValue();
             }
             addAlias((String) entry.getKey(), type);
         }
     }
 
     /**
      * Adds an alias for the given type.
      *
      * @param name alias to be used for the type
      * @param type the type to be aliased
      */
     public void addAlias(String name, Class type) {
         getXStream().alias(name, type);
     }
 
     /**
      * Sets types to use XML attributes for.
      *
      * @see XStream#useAttributeFor(Class)
      */
     public void setUseAttributeForTypes(Class[] types) {
         for (int i = 0; i < types.length; i++) {
             getXStream().useAttributeFor(types[i]);
         }
     }
 
     /**
      * Sets the types to use XML attributes for. The given map can contain either <code>&lt;String, Class&gt;</code>
      * pairs, in which case {@link XStream#useAttributeFor(String,Class)} is called, or <code>&lt;Class,
      * String&gt;</code> pairs, which results in {@link XStream#useAttributeFor(Class,String)}.
      */
     public void setUseAttributeFor(Map attributes) {
         for (Iterator iterator = attributes.entrySet().iterator(); iterator.hasNext();) {
             Map.Entry entry = (Map.Entry) iterator.next();
             if (entry.getKey() instanceof String && entry.getValue() instanceof Class) {
                 getXStream().useAttributeFor((String) entry.getKey(), (Class) entry.getValue());
             }
             else if (entry.getKey() instanceof Class && entry.getValue() instanceof String) {
                 getXStream().useAttributeFor((Class) entry.getKey(), (String) entry.getValue());
             }
             else {
                 throw new IllegalArgumentException("Invalid attribute key and value pair. " +
                         "'useAttributesFor' property takes either a <String, Class> map or a <Class, String> map");
             }
         }
     }
 
     public boolean supports(Class clazz) {
         if (ObjectUtils.isEmpty(supportedClasses)) {
             return true;
         }
         else {
             for (int i = 0; i < supportedClasses.length; i++) {
                 if (supportedClasses[i].isAssignableFrom(clazz)) {
                     return true;
                 }
             }
             return false;
         }
     }
 
     /**
      * Convert the given XStream exception to an appropriate exception from the <code>org.springframework.oxm</code>
      * hierarchy.
      * <p/>
      * The default implementation delegates to <code>XStreamUtils</code>. Can be overridden in subclasses.
      *
      * @param ex          exception that occured
      * @param marshalling indicates whether the exception occurs during marshalling (<code>true</code>), or
      *                    unmarshalling (<code>false</code>)
      * @return the corresponding <code>XmlMappingException</code> instance
      * @see XStreamUtils#convertXStreamException(Exception,boolean)
      */
     public XmlMappingException convertXStreamException(Exception ex, boolean marshalling) {
         return XStreamUtils.convertXStreamException(ex, marshalling);
     }
 
     /**
      * Marshals the given graph to the given XStream HierarchicalStreamWriter. Converts exceptions using
      * <code>convertXStreamException</code>.
      */
     private void marshal(Object graph, HierarchicalStreamWriter streamWriter) {
         try {
             getXStream().marshal(graph, streamWriter);
         }
         catch (Exception ex) {
             throw convertXStreamException(ex, true);
         }
     }
 
     protected void marshalDomNode(Object graph, Node node) throws XmlMappingException {
         HierarchicalStreamWriter streamWriter;
         if (node instanceof Document) {
             streamWriter = new DomWriter((Document) node);
         }
         else if (node instanceof Element) {
             streamWriter = new DomWriter((Element) node);
         }
         else {
             throw new IllegalArgumentException("DOMResult contains neither Document nor Element");
         }
         marshal(graph, streamWriter);
     }
 
     protected void marshalXmlEventWriter(Object graph, XMLEventWriter eventWriter) throws XmlMappingException {
         ContentHandler contentHandler = new StaxEventContentHandler(eventWriter);
         marshalSaxHandlers(graph, contentHandler, null);
     }
 
     protected void marshalXmlStreamWriter(Object graph, XMLStreamWriter streamWriter) throws XmlMappingException {
         try {
             marshal(graph, new StaxWriter(new QNameMap(), streamWriter));
         }
         catch (XMLStreamException ex) {
             throw convertXStreamException(ex, true);
         }
     }
 
     protected void marshalOutputStream(Object graph, OutputStream outputStream)
             throws XmlMappingException, IOException {
         marshalWriter(graph, new OutputStreamWriter(outputStream, getEncoding()));
     }
 
     protected void marshalSaxHandlers(Object graph, ContentHandler contentHandler, LexicalHandler lexicalHandler)
             throws XmlMappingException {
         SaxWriter saxWriter = new SaxWriter();
         saxWriter.setContentHandler(contentHandler);
         marshal(graph, saxWriter);
     }
 
     protected void marshalWriter(Object graph, Writer writer) throws XmlMappingException, IOException {
         marshal(graph, new CompactWriter(writer));
     }
 
     private Object unmarshal(HierarchicalStreamReader streamReader) {
         try {
             return getXStream().unmarshal(streamReader);
         }
         catch (Exception ex) {
             throw convertXStreamException(ex, false);
         }
     }
 
     protected Object unmarshalDomNode(Node node) throws XmlMappingException {
         HierarchicalStreamReader streamReader;
         if (node instanceof Document) {
             streamReader = new DomReader((Document) node);
         }
         else if (node instanceof Element) {
             streamReader = new DomReader((Element) node);
         }
         else {
             throw new IllegalArgumentException("DOMSource contains neither Document nor Element");
         }
         return unmarshal(streamReader);
     }
 
     protected Object unmarshalXmlEventReader(XMLEventReader eventReader) throws XmlMappingException {
         try {
             XMLStreamReader streamReader = new XmlEventStreamReader(eventReader);
             return unmarshalXmlStreamReader(streamReader);
         }
         catch (XMLStreamException ex) {
             throw convertXStreamException(ex, false);
         }
     }
 
     protected Object unmarshalXmlStreamReader(XMLStreamReader streamReader) throws XmlMappingException {
         return unmarshal(new StaxReader(new QNameMap(), streamReader));
     }
 
     protected Object unmarshalInputStream(InputStream inputStream) throws XmlMappingException, IOException {
         return unmarshalReader(new InputStreamReader(inputStream, getEncoding()));
     }
 
     protected Object unmarshalReader(Reader reader) throws XmlMappingException, IOException {
         return unmarshal(new XppReader(reader));
     }
 
     protected Object unmarshalSaxReader(XMLReader xmlReader, InputSource inputSource)
             throws XmlMappingException, IOException {
         throw new UnsupportedOperationException(
                 "XStreamMarshaller does not support unmarshalling using SAX XMLReaders");
     }
 }