/*
    * 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.xstream;
  
  import com.google.inject.Injector;
  
  import com.thoughtworks.xstream.converters.ConversionException;
  import com.thoughtworks.xstream.converters.Converter;
  import com.thoughtworks.xstream.converters.MarshallingContext;
  import com.thoughtworks.xstream.converters.UnmarshallingContext;
  import com.thoughtworks.xstream.io.ExtendedHierarchicalStreamWriterHelper;
  import com.thoughtworks.xstream.io.HierarchicalStreamReader;
  import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
  import com.thoughtworks.xstream.mapper.Mapper;
  
  import org.apache.shindig.social.opensocial.model.Exportablebean;
  
  import java.util.Collection;
  import java.util.Iterator;
  
  /***
   * 
   */
  public class GuiceBeanConverter implements Converter {
    private Mapper mapper;
    private GuiceBeanProvider beanProvider;
  
    public GuiceBeanConverter(Mapper mapper, Injector injector) {
      this(mapper, new GuiceBeanProvider(injector));
    }
  
    public GuiceBeanConverter(Mapper mapper, GuiceBeanProvider beanProvider) {
      this.mapper = mapper;
      this.beanProvider = beanProvider;
    }
  
    /***
     * Only checks for the availability of a public default constructor. If you
     * need stricter checks, subclass JavaBeanConverter
     */
    public boolean canConvert(Class type) {
      if ( type == null ) {
        return false;
      }
      if (Object.class.equals(type)) {
        return false;
      }
      if ( type.isInterface() ) {
        return true;
      }
      for (Class<?> iff : type.getInterfaces()) {
        if (iff.isAnnotationPresent(Exportablebean.class)) {
          return true;
        }
      }
      return canConvert(type.getSuperclass());
    }
  
    public void marshal(final Object source,
        final HierarchicalStreamWriter writer, final MarshallingContext context) {
      beanProvider.visitSerializableProperties(source,
          new GuiceBeanProvider.Visitor() {
            public boolean shouldVisit(String name, Class<?> definedIn) {
              return mapper.shouldSerializeMember(definedIn, name);
            }
  
            public void visit(String propertyName, Class<?> fieldType,
                Class<?> definedIn, Object newObj) {
              if (newObj != null) {
                Mapper.ImplicitCollectionMapping mapping = mapper
                    .getImplicitCollectionDefForFieldName(source.getClass(),
                        propertyName);
                if (mapping != null) {
                  if (mapping.getItemFieldName() != null) {
                    Collection<?> list = (Collection<?>) newObj;
                    for (Iterator<?> iter = list.iterator(); iter.hasNext();) {
                      Object obj = iter.next();
                      writeField(propertyName, mapping.getItemFieldName(),
                          mapping.getItemType(), definedIn, obj);
                    }
                  } else {
                    context.convertAnother(newObj);
                  }
                } else {
                 writeField(propertyName, propertyName, fieldType, definedIn,
                     newObj);
               }
             }
           }
 
           private void writeField(String propertyName, String aliasName,
               Class<?> fieldType, Class<?> definedIn, Object newObj) {
             ExtendedHierarchicalStreamWriterHelper.startNode(writer, mapper
                 .serializedMember(source.getClass(), aliasName), fieldType);
             context.convertAnother(newObj);
             writer.endNode();
 
           }
         });
   }
 
   public Object unmarshal(final HierarchicalStreamReader reader,
       final UnmarshallingContext context) {
     final Object result = instantiateNewInstance(context);
 
     while (reader.hasMoreChildren()) {
       reader.moveDown();
 
       String propertyName = mapper.realMember(result.getClass(), reader
           .getNodeName());
 
       boolean propertyExistsInClass = beanProvider.propertyDefinedInClass(
           propertyName, result.getClass());
 
       if (propertyExistsInClass) {
         Class<?> type = determineType(reader, result, propertyName);
         Object value = context.convertAnother(result, type);
         beanProvider.writeProperty(result, propertyName, value);
       } else if (mapper.shouldSerializeMember(result.getClass(), propertyName)) {
         throw new ConversionException("Property '" + propertyName
             + "' not defined in class " + result.getClass().getName());
       }
 
       reader.moveUp();
     }
 
     return result;
   }
 
   private Object instantiateNewInstance(UnmarshallingContext context) {
     Object result = context.currentObject();
     if (result == null) {
       result = beanProvider.newInstance(context.getRequiredType());
     }
     return result;
   }
 
   private Class<?> determineType(HierarchicalStreamReader reader,
       Object result, String fieldName) {
     final String classAttributeName = mapper.attributeForAlias("class");
     String classAttribute = reader.getAttribute(classAttributeName);
     if (classAttribute != null) {
       return mapper.realClass(classAttribute);
     } else {
       return mapper.defaultImplementationOf(beanProvider.getPropertyType(
           result, fieldName));
     }
   }
 
   /***
    * @deprecated since 1.3
    */
   public static class DuplicateFieldException extends ConversionException {
     public DuplicateFieldException(String msg) {
       super(msg);
     }
   }
 
 }