/**
    * This file Copyright (c) 2011 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.rendering.context;
  
  import info.magnolia.cms.core.AggregationState;
  import info.magnolia.cms.core.Content;
  import info.magnolia.cms.util.ContentUtil;
  import info.magnolia.objectfactory.annotation.RequestScoped;
  import info.magnolia.rendering.engine.OutputProvider;
  import info.magnolia.rendering.engine.RenderException;
  import info.magnolia.rendering.engine.RenderExceptionHandler;
  import info.magnolia.rendering.template.RenderableDefinition;
  import info.magnolia.rendering.util.AppendableWriter;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.Writer;
  import java.util.EmptyStackException;
  import java.util.Stack;
  
  import javax.inject.Inject;
  import javax.inject.Provider;
  import javax.jcr.Node;
  
  /**
   * RenderingContext implementation that uses AggregationState.
   *
   * @version $Id$
   */
  @RequestScoped
  public class AggregationStateBasedRenderingContext implements RenderingContext {
  
      // TODO dlipp: add reasonable javadoc! Uses and updates the {@link AggregationState}.
      // FIXME we should not use the AggregationState anymore
  
      private static class StackState {
  
          RenderableDefinition renderableDefinition;
          OutputProvider outputProvider;
          Content legacyContent;
  
          private StackState(RenderableDefinition renderableDefinition, OutputProvider outputProvider, Content legacyContent) {
              this.renderableDefinition = renderableDefinition;
              this.outputProvider = outputProvider;
              this.legacyContent = legacyContent;
          }
      }
  
      private final AggregationState aggregationState;
      private final Stack<StackState> stack = new Stack<StackState>();
      private RenderableDefinition currentRenderableDefinition;
      private OutputProvider currentOutputProvider;
      private RenderExceptionHandler exceptionHandler;
  
      /**
       * We keep the current state in local variables and start using the stack only for the second push operation. This
       * variable is 0 before the first push, 1 when we have local variables set, and greater than 1 when we have things
       * on stack.
       */
      private int depth = 0;
  
      @Inject
      public AggregationStateBasedRenderingContext(Provider<AggregationState> aggregationStateProvider, RenderExceptionHandler exceptionHandler) {
          this(aggregationStateProvider.get(), exceptionHandler);
      }
  
      public AggregationStateBasedRenderingContext(AggregationState aggregationState, RenderExceptionHandler exceptionHandler) {
          this.aggregationState = aggregationState;
         this.exceptionHandler = exceptionHandler;
     }
 
     @Override
     public Node getMainContent() {
         // there is still a possibility of call to this method before push!
         Content mainContent = aggregationState.getMainContent();
         return mainContent != null ? mainContent.getJCRNode() : null;
     }
 
     @Override
     public Node getCurrentContent() {
         Content currentContent = aggregationState.getCurrentContent();
         return currentContent != null ? currentContent.getJCRNode() : null;
     }
 
     @Override
     public RenderableDefinition getRenderableDefinition() {
         return currentRenderableDefinition;
     }
 
     @Override
     public void push(Node content, RenderableDefinition renderableDefinition) {
         push(content, renderableDefinition, null);
     }
 
     @Override
     public void push(Node content, RenderableDefinition renderableDefinition, OutputProvider outputProvider) {
 
         // Creating the Content object can fail with an exception, by doing it before anything else we don't risk ending
         // up having inconsistent state due to a partially completed push.
         Content legacyContent = ContentUtil.asContent(content);
 
         if (aggregationState.getMainContent() == null) {
             aggregationState.setMainContent(legacyContent);
         }
 
         if (depth > 0) {
             stack.push(new StackState(currentRenderableDefinition, currentOutputProvider, aggregationState.getCurrentContent()));
         }
         aggregationState.setCurrentContent(legacyContent);
         currentRenderableDefinition = renderableDefinition;
         currentOutputProvider = outputProvider != null ? outputProvider : currentOutputProvider;
         depth++;
     }
 
     @Override
     public void pop() {
         if (depth == 0) {
             throw new EmptyStackException();
         } else if (depth == 1) {
             aggregationState.setCurrentContent(null);
             currentRenderableDefinition = null;
             currentOutputProvider = null;
         } else {
             StackState state = stack.pop();
             aggregationState.setCurrentContent(state.legacyContent);
             currentRenderableDefinition = state.renderableDefinition;
             currentOutputProvider = state.outputProvider;
         }
         depth--;
         // Note that we do not restore main content
     }
 
     @Override
     public OutputProvider getOutputProvider() {
         return currentOutputProvider;
     }
 
     @Override
     public AppendableWriter getAppendable() throws RenderException, IOException {
         return new AppendableWriter(this.currentOutputProvider.getAppendable());
     }
 
     @Override
     public OutputStream getOutputStream() throws RenderException, IOException {
         return this.currentOutputProvider.getOutputStream();
     }
 
     @Override
     public void handleException(RenderException renderException, Writer out) {
         exceptionHandler.handleException(renderException, out);
     }
 }