/*

  * 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.shindig.social.core.util;

 import com.google.common.collect.Maps;

 import com.google.inject.Inject;

 import com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider;

 import com.thoughtworks.xstream.converters.reflection.ReflectionProvider;

 import com.thoughtworks.xstream.io.HierarchicalStreamDriver;

 import com.thoughtworks.xstream.io.xml.StaxDriver;

 import com.thoughtworks.xstream.io.xml.XppDriver;

 import com.thoughtworks.xstream.mapper.DefaultMapper;

 import com.thoughtworks.xstream.mapper.Mapper;

 import org.apache.shindig.social.core.util.xstream.StackDriver;

 import org.apache.shindig.social.core.util.xstream.ThreadSafeWriterStack;

 import org.apache.shindig.social.core.util.xstream.WriterStack;

 import org.apache.shindig.social.core.util.xstream.XStreamConfiguration;

 import org.apache.shindig.social.core.util.xstream.XStreamConfiguration.ConverterConfig;

 import org.apache.shindig.social.opensocial.service.BeanConverter;

 import org.apache.shindig.social.opensocial.spi.DataCollection;

 import org.apache.shindig.social.opensocial.spi.RestfulCollection;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import java.util.HashMap;

 import java.util.Map;

 public class BeanXStreamConverter implements BeanConverter {

   public static final String XML_DECL = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>";

   private static final XStreamConfiguration.ConverterSet[] MAPPER_SCOPES = new XStreamConfiguration.ConverterSet[] {

       XStreamConfiguration.ConverterSet.MAP,

       XStreamConfiguration.ConverterSet.COLLECTION,

       XStreamConfiguration.ConverterSet.DEFAULT };

   private static Log log = LogFactory.getLog(BeanXStreamConverter.class);

   private ReflectionProvider rp;

   private HierarchicalStreamDriver driver;

   protected WriterStack writerStack;

   protected Map<XStreamConfiguration.ConverterSet, ConverterConfig> converterMap = Maps.newHashMap();

   @Inject

   public BeanXStreamConverter(XStreamConfiguration configuration) {

     rp = new PureJavaReflectionProvider();

     Mapper dmapper = new DefaultMapper(this.getClass().getClassLoader());

     /*

      * Putting this here means only one conversion per thread may be active at

      * any one time, but since the conversion process is atomic this will not

      * matter unless the class is extended.

      */

     writerStack = new ThreadSafeWriterStack();

     /*

      * create a driver that wires into a standard driver, and updates the stack

      * position.

      */

     driver = new StackDriver(new XppDriver(), writerStack, configuration.getNameSpaces());

     /*

      * Create an interface class mapper that understands class hierarchy for

      * single items

      */

     for (XStreamConfiguration.ConverterSet c : MAPPER_SCOPES) {

       converterMap.put(c, configuration.getConverterConfig(c,rp,dmapper,driver,writerStack));

     }

   }

   public String getContentType() {

     return "application/xml";

   }

   public String convertToString(Object pojo) {

     return convertToXml(pojo);

   }

   /**

    * convert an Object to XML, but make certain that only one of these is run on

    * a thread at any one time. This only matters if this class is extended.

    *

    * @param obj

    * @return

    */

   private String convertToXml(Object obj) {

     writerStack.reset();

     if (obj instanceof Map) {

       Map<?, ?> m = (Map<?, ?>) obj;

       ConverterConfig cc = converterMap

           .get(XStreamConfiguration.ConverterSet.MAP);

       if (m.size() == 1) {

         Object s = m.values().iterator().next();

         cc.mapper.setBaseObject(s); // thread safe method

         String result = cc.xstream.toXML(s);

         log.debug("Result is " + result);

         return "<response>" + result + "</response>";

       }

     } else if (obj instanceof RestfulCollection) {

       ConverterConfig cc = converterMap

           .get(XStreamConfiguration.ConverterSet.COLLECTION);

       cc.mapper.setBaseObject(obj); // thread safe method

       String result = cc.xstream.toXML(obj);

       log.debug("Result is " + result);

       return result;

     } else if (obj instanceof DataCollection) {

       ConverterConfig cc = converterMap

           .get(XStreamConfiguration.ConverterSet.MAP);

       cc.mapper.setBaseObject(obj); // thread safe method

       String result = cc.xstream.toXML(obj);

       log.debug("Result is " + result);

       return result;

     }

     ConverterConfig cc = converterMap

         .get(XStreamConfiguration.ConverterSet.DEFAULT);

     cc.mapper.setBaseObject(obj); // thread safe method

     String result = cc.xstream.toXML(obj);

     log.debug("Result is " + result);

     return "<response>" + result + "</response>";

   }

   @SuppressWarnings("unchecked")

   public <T> T convertToObject(String xml, Class<T> className) {

     ConverterConfig cc = converterMap.get(XStreamConfiguration.ConverterSet.DEFAULT);

     return (T) cc.xstream.fromXML(xml);

   }

 }