/*
    * Copyright 2006-2013 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.batch.core.repository.dao;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.OutputStream;
  
  import org.springframework.batch.core.repository.ExecutionContextSerializer;
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.core.serializer.Deserializer;
  import org.springframework.core.serializer.Serializer;
  import org.springframework.util.Assert;
  
  import com.thoughtworks.xstream.XStream;
  import com.thoughtworks.xstream.converters.reflection.ReflectionProvider;
  import com.thoughtworks.xstream.io.HierarchicalStreamDriver;
  import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;
  
  /**
   * Implementation that uses XStream and Jettison to provide serialization.
   *
   * @author Thomas Risberg
   * @author Michael Minella
   * @since 2.0
   * @see ExecutionContextSerializer
   */
  public class XStreamExecutionContextStringSerializer implements ExecutionContextSerializer, InitializingBean {
  
  	private ReflectionProvider reflectionProvider = null;
  
  	private HierarchicalStreamDriver hierarchicalStreamDriver;
  
  	private XStream xstream;
  
  	public void setReflectionProvider(ReflectionProvider reflectionProvider) {
  		this.reflectionProvider = reflectionProvider;
  	}
  
  	public void setHierarchicalStreamDriver(HierarchicalStreamDriver hierarchicalStreamDriver) {
  		this.hierarchicalStreamDriver = hierarchicalStreamDriver;
  	}
  
  	@Override
  	public void afterPropertiesSet() throws Exception {
  		init();
  	}
  
  	public synchronized void init() throws Exception {
  		if (hierarchicalStreamDriver == null) {
  			this.hierarchicalStreamDriver = new JettisonMappedXmlDriver();
  		}
  		if (reflectionProvider == null) {
  			xstream =  new XStream(hierarchicalStreamDriver);
  		}
  		else {
  			xstream = new XStream(reflectionProvider, hierarchicalStreamDriver);
  		}
  	}
  
  	/**
  	 * Serializes the passed execution context to the supplied OutputStream.
  	 *
  	 * @param context
  	 * @param out
  	 * @see Serializer#serialize(Object, OutputStream)
  	 */
  	@Override
  	public void serialize(Object context, OutputStream out) throws IOException {
  		Assert.notNull(context);
  		Assert.notNull(out);
  
  		out.write(xstream.toXML(context).getBytes());
  	}
  
  	/**
  	 * Deserializes the supplied input stream into a new execution context.
  	 *
  	 * @param in
  	 * @return a reconstructed execution context
  	 * @see Deserializer#deserialize(InputStream)
  	 */
  	@Override
 	public Object deserialize(InputStream in) throws IOException {
 		BufferedReader br = new BufferedReader(new InputStreamReader(in));
 
 		StringBuilder sb = new StringBuilder();
 
 		String line;
 		while ((line = br.readLine()) != null) {
 			sb.append(line);
 		}
 
 		return xstream.fromXML(sb.toString());
 	}
 }