/*

  * 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);

     }

 }