/*
    * 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.myfaces.view.facelets;
  
  import org.apache.myfaces.view.facelets.util.FastWriter;
  
  import javax.faces.context.FacesContext;
  import java.io.IOException;
  import java.io.Writer;
  
  /**
   * A class for handling state insertion. Content is written directly to "out" until an attempt to write state; at that
   * point, it's redirected into a buffer that can be picked through in theory, this buffer should be very small, since it
   * only needs to be enough to contain all the content after the close of the first (and, hopefully, only) form.
   * <p>
   * Potential optimizations:
   * <ul>
   * <li>If we created a new FastWriter at each call to writingState(), and stored a List of them, then we'd know that
   * state tokens could only possibly be near the start of each buffer (and might not be there at all). (There might be a
   * close-element before the state token). Then, we'd only need to check the start of the buffer for the state token; if
   * it's there, write out the real state, then blast the rest of the buffer out. This wouldn't even require toString(),
   * which for large buffers is expensive. However, this optimization is only going to be especially meaningful for the
   * multi-form case.</li>
   * <li>More of a FastWriter optimization than a StateWriter, but: it is far faster to create a set of small 1K buffers
   * than constantly reallocating one big buffer.</li>
   * </ul>
   * 
   * @author Adam Winer
   * @version $Id$
   */
  public final class StateWriter extends Writer
  {
  
      private static final String CURRENT_WRITER_KEY = "org.apache.myfaces.view.facelets.StateWriter.CURRENT_WRITER";
  
      private int initialSize;
      private Writer out;
      private FastWriter fast;
      private boolean writtenState;
      private boolean writtenStateWithoutWrapper;
  
      static public StateWriter getCurrentInstance()
      {
          FacesContext facesContext = FacesContext.getCurrentInstance();
  
          return (StateWriter)facesContext.getAttributes().get(CURRENT_WRITER_KEY);
      }
          
      static public StateWriter getCurrentInstance(FacesContext facesContext)
      {
          return (StateWriter)facesContext.getAttributes().get(CURRENT_WRITER_KEY);
      }
  
      private static void setCurrentInstance(StateWriter stateWriter)
      {
          FacesContext facesContext = FacesContext.getCurrentInstance();
  
          if (stateWriter == null)
          {
              facesContext.getAttributes().remove(CURRENT_WRITER_KEY);
          }
          else
          {
              facesContext.getAttributes().put(CURRENT_WRITER_KEY, stateWriter);
          }
      }
      
      private static void setCurrentInstance(StateWriter stateWriter, FacesContext facesContext)
      {
          //FacesContext facesContext = FacesContext.getCurrentInstance();
  
          if (stateWriter == null)
          {
              facesContext.getAttributes().remove(CURRENT_WRITER_KEY);
          }
          else
          {
              facesContext.getAttributes().put(CURRENT_WRITER_KEY, stateWriter);
          }
      }
  
      public StateWriter(Writer initialOut, int initialSize)
      {
         if (initialSize < 0)
         {
             throw new IllegalArgumentException("Initial Size cannot be less than 0");
         }
 
         this.initialSize = initialSize;
         this.out = initialOut;
         setCurrentInstance(this);
     }
     
     public StateWriter(Writer initialOut, int initialSize, FacesContext facesContext)
     {
         if (initialSize < 0)
         {
             throw new IllegalArgumentException("Initial Size cannot be less than 0");
         }
 
         this.initialSize = initialSize;
         this.out = initialOut;
         setCurrentInstance(this, facesContext);
     }
 
     /**
      * Mark that state is about to be written. Contrary to what you'd expect, we cannot and should not assume that this
      * location is really going to have state; it is perfectly legit to have a ResponseWriter that filters out content,
      * and ignores an attempt to write out state at this point. So, we have to check after the fact to see if there
      * really are state markers.
      */
     public void writingState()
     {
         if (!this.writtenState)
         {
             this.writtenState = true;
             this.writtenStateWithoutWrapper = false;
             this.fast = new FastWriter(this.initialSize);
             this.out = this.fast;
         }
     }
     
     public boolean isStateWritten()
     {
         return this.writtenState;
     }
 
     public void writingStateWithoutWrapper()
     {
         if (!this.writtenState && !this.writtenStateWithoutWrapper)
         {
             this.writtenStateWithoutWrapper = true;
         }
     }    
 
     public boolean isStateWrittenWithoutWrapper()
     {
         return this.writtenStateWithoutWrapper;
     }
 
     public void close() throws IOException
     {
         // do nothing
     }
 
     public void flush() throws IOException
     {
         if (!this.writtenState)
         {
             this.out.flush();
         }
     }
 
     public void write(char[] cbuf, int off, int len) throws IOException
     {
         this.out.write(cbuf, off, len);
     }
 
     public void write(char[] cbuf) throws IOException
     {
         this.out.write(cbuf);
     }
 
     public void write(int c) throws IOException
     {
         this.out.write(c);
     }
 
     public void write(String str, int off, int len) throws IOException
     {
         this.out.write(str, off, len);
     }
 
     public void write(String str) throws IOException
     {
         this.out.write(str);
     }
 
     public String getAndResetBuffer()
     {
         if (!this.writtenState)
         {
             throw new IllegalStateException("Did not write state;  no buffer is available");
         }
 
         String result = this.fast.toString();
         this.fast.reset();
         return result;
     }
 
     public void release()
     {
         // remove from FacesContext attribute Map
         setCurrentInstance(null);
     }
     
     public void release(FacesContext facesContext)
     {
         // remove from FacesContext attribute Map
         setCurrentInstance(null, facesContext);
     }
 
 }