//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.spdy.api;
  
  import java.nio.ByteBuffer;
  import java.nio.charset.Charset;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicInteger;
  
  /**
   * <p>A container for DATA frames metadata and content bytes.</p>
   * <p>Specialized subclasses (like {@link StringDataInfo}) may be used by applications
   * to send specific types of content.</p>
   * <p>Applications may send multiple instances of {@link DataInfo}, usually of the same
   * type, via {@link Stream#data(DataInfo)}. The last instance must have the
   * {@link #isClose() close flag} set, so that the client knows that no more content is
   * expected.</p>
   * <p>Receivers of {@link DataInfo} via {@link StreamFrameListener#onData(Stream, DataInfo)}
   * have two different APIs to read the data content bytes: a {@link #readInto(ByteBuffer) read}
   * API that does not interact with flow control, and a {@link #consumeInto(ByteBuffer) drain}
   * API that interacts with flow control.</p>
   * <p>Flow control is defined so that when the sender wants to sends a number of bytes larger
   * than the {@link Settings.ID#INITIAL_WINDOW_SIZE} value, it will stop sending as soon as it
   * has sent a number of bytes equal to the window size. The receiver has to <em>consume</em>
   * the data bytes that it received in order to tell the sender to send more bytes.</p>
   * <p>Consuming the data bytes can be done only via {@link #consumeInto(ByteBuffer)} or by a combination
   * of {@link #readInto(ByteBuffer)} and {@link #consume(int)} (possibly at different times).</p>
   */
  public abstract class DataInfo extends Info
  {
      /**
       * <p>Flag that indicates that this {@link DataInfo} is the last frame in the stream.</p>
       *
       * @see #isClose()
       * @see #getFlags()
       */
      public final static byte FLAG_CLOSE = 1;
  
      private final AtomicInteger consumed = new AtomicInteger();
      private boolean close;
  
      /**
       * <p>Creates a new {@link DataInfo} with the given close flag and no compression flag.</p>
       *
       * @param close the value of the close flag
       */
      public DataInfo(boolean close)
      {
          setClose(close);
      }
  
      /**
       * <p>Creates a new {@link DataInfo} with the given close flag and no compression flag.</p>
       *
       * @param timeout
       * @param unit
       * @param close the value of the close flag
       */
      protected DataInfo(long timeout, TimeUnit unit, boolean close)
      {
          super(timeout, unit);
          this.close = close;
      }
  
      /**
       * @return the value of the close flag
       * @see #setClose(boolean)
       */
      public boolean isClose()
      {
          return close;
      }
  
      /**
       * @param close the value of the close flag
       * @see #isClose()
       */
      public void setClose(boolean close)
      {
          this.close = close;
      }
  
      /**
      * @return the close and compress flags as integer
      * @see #FLAG_CLOSE
      */
     public byte getFlags()
     {
         return isClose() ? FLAG_CLOSE : 0;
     }
 
     /**
      * @return the total number of content bytes
      * @see #available()
      */
     public abstract int length();
 
     /**
      * <p>Returns the available content bytes that can be read via {@link #readInto(ByteBuffer)}.</p>
      * <p>Each invocation to {@link #readInto(ByteBuffer)} modifies the value returned by this method,
      * until no more content bytes are available.</p>
      *
      * @return the available content bytes
      * @see #readInto(ByteBuffer)
      */
     public abstract int available();
 
     /**
      * <p>Copies the content bytes of this {@link DataInfo} into the given {@link ByteBuffer}.</p>
      * <p>If the given {@link ByteBuffer} cannot contain the whole content of this {@link DataInfo}
      * then after the read {@link #available()} will return a positive value, and further content
      * may be retrieved by invoking again this method with a new output buffer.</p>
      *
      * @param output the {@link ByteBuffer} to copy the bytes into
      * @return the number of bytes copied
      * @see #available()
      * @see #consumeInto(ByteBuffer)
      */
     public abstract int readInto(ByteBuffer output);
 
     /**
      * <p>Copies the content bytes of this {@link DataInfo} into the given byte array.</p>
      * <p>If the given byte array cannot contain the whole content of this {@link DataInfo}
      * then after the read {@link #available()} will return a positive value, and further content
      * may be retrieved by invoking again this method with a new byte array.</p>
      *
      * @param bytes the byte array to copy the bytes into
      * @param offset the index of the byte array to start copying
      * @param length the number of bytes to copy
      * @return the number of bytes copied
      */
     public abstract int readInto(byte[] bytes, int offset, int length);
 
     /**
      * <p>Reads and consumes the content bytes of this {@link DataInfo} into the given {@link ByteBuffer}.</p>
      *
      * @param output the {@link ByteBuffer} to copy the bytes into
      * @return the number of bytes copied
      * @see #consume(int)
      */
     public int consumeInto(ByteBuffer output)
     {
         int read = readInto(output);
         consume(read);
         return read;
     }
 
     /**
      * <p>Reads and consumes the content bytes of this {@link DataInfo} into the given byte array,
      * starting from index {@code offset} for {@code length} bytes.</p>
      *
      * @param bytes the byte array to copy the bytes into
      * @param offset the offset of the byte array to start copying
      * @param length the number of bytes to copy
      * @return the number of bytes copied
      */
     public int consumeInto(byte[] bytes, int offset, int length)
     {
         int read = readInto(bytes, offset, length);
         consume(read);
         return read;
     }
 
     /**
      * <p>Consumes the given number of bytes from this {@link DataInfo}.</p>
      *
      * @param delta the number of bytes consumed
      */
     public void consume(int delta)
     {
         if (delta < 0)
             throw new IllegalArgumentException();
         int read = length() - available();
         int newConsumed = consumed() + delta;
 //        if (newConsumed > read)
 //            throw new IllegalStateException("Consuming without reading: consumed " + newConsumed + " but only read " + read);
         consumed.addAndGet(delta);
     }
 
     /**
      * @return the number of bytes consumed
      */
     public int consumed()
     {
         return consumed.get();
     }
 
     /**
      *
      * @param charset the charset used to convert the bytes
      * @param consume whether to consume the content
      * @return a String with the content of this {@link DataInfo}
      */
     public String asString(String charset, boolean consume)
     {
         return asString(Charset.forName(charset), consume);
     }
 
     /**
      *
      * @param charset the charset used to convert the bytes
      * @param consume whether to consume the content
      * @return a String with the content of this {@link DataInfo}
      */
     public String asString(Charset charset, boolean consume)
     {
         ByteBuffer buffer = asByteBuffer(consume);
         return charset.decode(buffer).toString();
     }
 
     /**
      * @return a byte array with the content of this {@link DataInfo}
      * @param consume whether to consume the content
      */
     public byte[] asBytes(boolean consume)
     {
         ByteBuffer buffer = asByteBuffer(consume);
         byte[] result = new byte[buffer.remaining()];
         buffer.get(result);
         return result;
     }
 
     /**
      * @return a {@link ByteBuffer} with the content of this {@link DataInfo}
      * @param consume whether to consume the content
      */
     public ByteBuffer asByteBuffer(boolean consume)
     {
         ByteBuffer buffer = allocate(available());
         if (consume)
             consumeInto(buffer);
         else
             readInto(buffer);
         buffer.flip();
         return buffer;
     }
 
     protected ByteBuffer allocate(int size)
     {
         return ByteBuffer.allocate(size);
     }
 
     @Override
     public String toString()
     {
         return String.format("DATA @%x available=%d consumed=%d close=%b", hashCode(), available(), consumed(), isClose());
     }
 }