/*

  * 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.thoughtworks.xstream.io.HierarchicalStreamWriter;

 import com.thoughtworks.xstream.io.WriterWrapper;

 import java.util.Map;

 import java.util.Map.Entry;

 /**

  * A Writer that provides a Stack based tracking of the location of the

  * underlying writer.

  */

 public class StackWriterWrapper extends WriterWrapper {

   /**

    * The stack that keeps track of current node.

    */

   private WriterStack writerStack;

   private Map<String, NamespaceSet> namespaces;

   /**

    * Create a {@link StackWriterWrapper} that wraps a

    * {@link HierarchicalStreamWriter} and tracks where that writer is in the

    * hierarchy.

    *

    * @param wrapped

    *          the underlying writer

    * @param writerStack

    *          the stack that will record where the writer is.

    * @param namespaces

    */

   public StackWriterWrapper(HierarchicalStreamWriter wrapped,

       WriterStack writerStack, Map<String, NamespaceSet> namespaces) {

     super(wrapped);

     this.writerStack = writerStack;

     this.namespaces = namespaces;

   }

   /**

    * Set attribute values on the current node, but filter out class attributes

    * from the writer, this is not strictly a feature of this class, but is

    * required (for shindig to meet the XSD requirements.

    *

    * @param name

    *          the name of attribute

    * @param value

    *          the value of the attribute.

    * @see com.thoughtworks.xstream.io.WriterWrapper#addAttribute(java.lang.String,

    *      java.lang.String)

    */

   public void addAttribute(String name, String value) {

     if (!"class".equals(name)) {

       super.addAttribute(name, value);

     }

   }

   /**

    * Begin a new element or node of the supplied name.

    *

    * @param name

    *          the name of the node.

    *

    * @see com.thoughtworks.xstream.io.WriterWrapper#startNode(java.lang.String )

    */

   @Override

   public void startNode(String name) {

     super.startNode(translateName(name));

     addNamespace(name);

   }

   /**

    * Start a node with a specific class. This may invoke

    * {@link StackWriterWrapper#startNode(String)} so we might have double

    * recording of the position in the stack. This would be a bug.

    *

    * @see com.thoughtworks.xstream.io.WriterWrapper#startNode(java.lang.String ,

    *      java.lang.Class)

    */

   @SuppressWarnings("unchecked")

   // API is not generic

   @Override

   public void startNode(String name, Class clazz) {

     super.startNode(translateName(name), clazz);

     addNamespace(name);

   }

   /**

    * @param name

    * @return

    */

   private String translateName(String name) {

     NamespaceSet namespaceSet = namespaces.get(name);

     NamespaceSet currentNamespace = writerStack.peekNamespace();

     // specified by not current

     if (namespaceSet != null &&  namespaceSet != currentNamespace) {

         return namespaceSet.getElementName(name);

     }

     // current has been specified

     if ( currentNamespace != null ) {

       return currentNamespace.getElementName(name);

     }

     return name;

   }

   /**

    * @param name

    */

   private void addNamespace(String name) {

     NamespaceSet namespaceSet = namespaces.get(name);

     NamespaceSet currentNamespace = writerStack.peekNamespace();

     // specified and not current

     if ( namespaceSet != null && namespaceSet != currentNamespace ) {

       for (Entry<String, String> e : namespaceSet.nameSpaceEntrySet()) {

         super.addAttribute(e.getKey(), e.getValue());

       }

       currentNamespace = namespaceSet;

     }

     writerStack.push(name, currentNamespace);

   }

   /**

    * End the current node, making the parent node the active node.

    *

    * @see com.thoughtworks.xstream.io.WriterWrapper#endNode()

    */

   @Override

   public void endNode() {

     writerStack.pop();

     super.endNode();

   }

 }