package org.kuali.rice.krad.service.impl;
   
   import com.thoughtworks.xstream.XStream;
   import com.thoughtworks.xstream.converters.MarshallingContext;
   import com.thoughtworks.xstream.converters.UnmarshallingContext;
   import com.thoughtworks.xstream.converters.collections.CollectionConverter;
   import com.thoughtworks.xstream.converters.reflection.ObjectAccessException;
   import com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider;
   import com.thoughtworks.xstream.converters.reflection.ReflectionConverter;
  import com.thoughtworks.xstream.converters.reflection.ReflectionProvider;
  import com.thoughtworks.xstream.io.HierarchicalStreamReader;
  import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
  import com.thoughtworks.xstream.mapper.Mapper;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.ojb.broker.core.proxy.ListProxyDefaultImpl;
  import org.apache.ojb.broker.core.proxy.SetProxyDefaultImpl;
  import org.kuali.rice.krad.service.KRADServiceLocator;
  import org.kuali.rice.krad.service.PersistenceService;
  import org.kuali.rice.krad.service.XmlObjectSerializerService;
  
  import java.lang.reflect.Field;
  import java.util.*;
  
  /**
   * Created by sheiksalahudeenm on 16/4/15.
   */
  public class XmlObjectSerializerServiceImpl implements XmlObjectSerializerService {
      private static final Log LOG = LogFactory.getLog(XmlObjectSerializerServiceImpl.class);
  
  
      private PersistenceService persistenceService;
  
      private XStream xstream;
  
      public XmlObjectSerializerServiceImpl() {
          xstream = new XStream(new ProxyAwareJavaReflectionProvider());
          xstream.registerConverter(new ProxyConverter(xstream.getMapper(), xstream.getReflectionProvider()));
          xstream.addDefaultImplementation(ArrayList.class, ListProxyDefaultImpl.class);
  
          // register converters so that ListProxyDefaultImpl and SetProxyDefaultImpl are
          // serialized as ArrayLists and HashSets
          xstream.registerConverter(new ListProxyDefaultImplConverter(xstream.getMapper()));
          xstream.registerConverter(new SetProxyDefaultImplConverter(xstream.getMapper()));
      }
  
      /**
       * @see org.kuali.rice.krad.service.XmlObjectSerializer#toXml(Object)
       * @see org.kuali.rice.krad.service.XmlObjectSerializerService#toXml(Object)
       */
      public String toXml(Object object) {
          if (LOG.isDebugEnabled()) {
              LOG.debug("toXml(" + object + ") : \n" + xstream.toXML(object));
          }
          return xstream.toXML(object);
      }
  
      /**
       * @see org.kuali.rice.krad.service.XmlObjectSerializer#fromXml(String)
       * @see org.kuali.rice.krad.service.XmlObjectSerializerService#fromXml(String)
       */
      public Object fromXml(String xml) {
          if (LOG.isDebugEnabled()) {
              LOG.debug("fromXml() : \n" + xml);
          }
          if (xml != null) {
              xml = xml.replaceAll("--EnhancerByCGLIB--[0-9a-f]{0,8}", "");
          }
          return xstream.fromXML(xml);
      }
  
      /**
       * This custom converter only handles proxies for BusinessObjects.  List-type proxies are handled by configuring XStream to treat
       * ListProxyDefaultImpl as ArrayLists (see constructor for this service).
       */
      public class ProxyConverter extends ReflectionConverter {
          public ProxyConverter(Mapper mapper, ReflectionProvider reflectionProvider) {
              super(mapper, reflectionProvider);
          }
  
          @Override
          // since the ReflectionConverter supertype defines canConvert without using a parameterized Class type, we must declare
          // the overridden version the same way
          @SuppressWarnings("unchecked")
          public boolean canConvert(Class clazz) {
              return clazz.getName().contains("CGLIB");
          }
  
          @Override
          public void marshal(Object obj, HierarchicalStreamWriter writer, MarshallingContext context) {
              super.marshal(getPersistenceService().resolveProxy(obj), writer, context);
          }
  
          // we shouldn't need an unmarshal method because all proxy metadata is taken out of the XML, so we'll reserialize as a base BO.
      }
  
      public class ProxyAwareJavaReflectionProvider extends PureJavaReflectionProvider {
  
          public ProxyAwareJavaReflectionProvider() {
             super();
         }
 
         /**
          * @see com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider#visitSerializableFields(Object, com.thoughtworks.xstream.converters.reflection.ReflectionProvider.Visitor)
          */
         @Override
         public void visitSerializableFields(Object object, Visitor visitor) {
             for (Iterator iterator = fieldDictionary.fieldsFor(object.getClass()); iterator.hasNext(); ) {
                 Field field = (Field) iterator.next();
                 if (!fieldModifiersSupported(field)) {
                     continue;
                 }
                 validateFieldAccess(field);
                 Object value = null;
                 try {
                     value = field.get(object);
                     if (value != null && getPersistenceService().isProxied(value)) {
                         value = getPersistenceService().resolveProxy(value);
                     }
                 } catch (IllegalArgumentException e) {
                     throw new ObjectAccessException("Could not get field " + field.getClass() + "." + field.getName(), e);
                 } catch (IllegalAccessException e) {
                     throw new ObjectAccessException("Could not get field " + field.getClass() + "." + field.getName(), e);
                 }
                 visitor.visit(field.getName(), field.getType(), field.getDeclaringClass(), value);
             }
         }
 
 
     }
 
     public PersistenceService getPersistenceService() {
         if (persistenceService == null) {
             persistenceService = KRADServiceLocator.getPersistenceService();
         }
         return persistenceService;
     }
 
 
     /**
      * Custom {@link com.thoughtworks.xstream.converters.Converter} that moves elements from a
      * {@link org.apache.ojb.broker.core.proxy.ListProxyDefaultImpl} into an {@link java.util.ArrayList} and marshals that instead.
      */
     private static class ListProxyDefaultImplConverter extends CollectionConverter {
 
         ListProxyDefaultImplConverter(Mapper mapper) {
             super(mapper);
         }
 
         @Override
         @SuppressWarnings("unchecked")
         public boolean canConvert(Class type) {
             return ListProxyDefaultImpl.class.equals(type);
         }
 
         /**
          * moves elements from a {@link org.apache.ojb.broker.core.proxy.ListProxyDefaultImpl} into an {@link java.util.ArrayList} and marshals that instead.
          */
         @Override
         @SuppressWarnings("unchecked")
         public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
 
             // move data to an ArrayList
             ArrayList altered = new ArrayList((List) source);
             // and marshal that
             super.marshal(altered, writer, context);
         }
 
         /**
          * NOTE: using this class to unmarshal a ListProxyDefaultImpl inside Rice is unexpected, since those should
          * have been converted to ArrayLists during marshalling. However, in the interest of attempting to
          * provide a full Converter implementation here, we'll attempt to unmarshal it to an ArrayList by throwing
          * away all the funny fields that a ListProxyDefaultImpl contains (Helpfully, their names all start with "_")'
          */
         @Override
         @SuppressWarnings("unchecked")
         public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
 
             ArrayList result = null;
 
             while (reader.hasMoreChildren()) {
                 try {
                     reader.moveDown();
 
                     if (reader.getNodeName().startsWith("_")) {
                         // do nothing
                     } else {
                         if (result == null) {
                             result = new ArrayList();
                         } // lazy init
                         addCurrentElementToCollection(reader, context, result, result);
                     }
                 } finally {
                     reader.moveUp();
                 }
             }
 
             return result;
         }
     }
 
 
     /**
      * Custom {@link com.thoughtworks.xstream.converters.Converter} that moves elements from a
      * {@link org.apache.ojb.broker.core.proxy.SetProxyDefaultImpl} into a {@link java.util.HashSet} and marshals that instead.
      */
     private static class SetProxyDefaultImplConverter extends CollectionConverter {
 
         SetProxyDefaultImplConverter(Mapper mapper) {
             super(mapper);
         }
 
         @Override
         @SuppressWarnings("unchecked")
         public boolean canConvert(Class type) {
             return SetProxyDefaultImpl.class.equals(type);
         }
 
         /**
          * moves elements from a {@link org.apache.ojb.broker.core.proxy.SetProxyDefaultImpl} into a {@link java.util.HashSet} and marshals that instead.
          */
         @Override
         @SuppressWarnings("unchecked")
         public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
 
             // move data to a HashSet
             HashSet altered = new HashSet((Set) source);
             // and marshal that
             super.marshal(altered, writer, context);
         }
 
         /**
          * NOTE: using this class to unmarshal a SetProxyDefaultImpl inside Rice is unexpected, since those should
          * have been converted to HashSets during marshalling. However, in the interest of attempting to
          * provide a full Converter implementation here, we'll attempt to unmarshal it to an HashSet by throwing
          * away all the funny fields that a SetProxyDefaultImpl contains (Helpfully, their names all start with "_")'
          */
         @Override
         @SuppressWarnings("unchecked")
         public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
 
             HashSet result = null;
 
             while (reader.hasMoreChildren()) {
                 try {
                     reader.moveDown();
 
                     if (reader.getNodeName().startsWith("_")) {
                         // do nothing
                     } else {
                         if (result == null) {
                             result = new HashSet();
                         } // lazy init
                         addCurrentElementToCollection(reader, context, result, result);
                     }
                 } finally {
                     reader.moveUp();
                 }
             }
 
             return result;
         }
     }
 }