/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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.jboss.netty.buffer;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.nio.channels.ClosedChannelException;
  import java.nio.channels.GatheringByteChannel;
  import java.nio.channels.ScatteringByteChannel;
  
  /**
   * A NIO {@link ByteBuffer} based buffer.  It is recommended to use {@link ChannelBuffers#directBuffer(int)}
   * and {@link ChannelBuffers#wrappedBuffer(ByteBuffer)} instead of calling the
   * constructor explicitly.
   */
  public class ByteBufferBackedChannelBuffer extends AbstractChannelBuffer {
  
      private final ByteBuffer buffer;
      private final ByteOrder order;
      private final int capacity;
  
      /**
       * Creates a new buffer which wraps the specified buffer's slice.
       */
      public ByteBufferBackedChannelBuffer(ByteBuffer buffer) {
          if (buffer == null) {
              throw new NullPointerException("buffer");
          }
  
          order = buffer.order();
          this.buffer = buffer.slice().order(order);
          capacity = buffer.remaining();
          writerIndex(capacity);
      }
  
      private ByteBufferBackedChannelBuffer(ByteBufferBackedChannelBuffer buffer) {
          this.buffer = buffer.buffer;
          order = buffer.order;
          capacity = buffer.capacity;
          setIndex(buffer.readerIndex(), buffer.writerIndex());
      }
  
      public ChannelBufferFactory factory() {
          if (buffer.isDirect()) {
              return DirectChannelBufferFactory.getInstance(order());
          } else {
              return HeapChannelBufferFactory.getInstance(order());
          }
      }
  
      public boolean isDirect() {
          return buffer.isDirect();
      }
  
      public ByteOrder order() {
          return order;
      }
  
      public int capacity() {
          return capacity;
      }
  
      public boolean hasArray() {
          return buffer.hasArray();
      }
  
      public byte[] array() {
          return buffer.array();
      }
  
      public int arrayOffset() {
          return buffer.arrayOffset();
      }
  
      public byte getByte(int index) {
          return buffer.get(index);
      }
  
      public short getShort(int index) {
          return buffer.getShort(index);
      }
  
      public int getUnsignedMedium(int index) {
         return  (getByte(index)     & 0xff) << 16 |
                 (getByte(index + 1) & 0xff) <<  8 |
                 getByte(index + 2) & 0xff;
     }
 
     public int getInt(int index) {
         return buffer.getInt(index);
     }
 
     public long getLong(int index) {
         return buffer.getLong(index);
     }
 
     public void getBytes(int index, ChannelBuffer dst, int dstIndex, int length) {
         if (dst instanceof ByteBufferBackedChannelBuffer) {
             ByteBufferBackedChannelBuffer bbdst = (ByteBufferBackedChannelBuffer) dst;
             ByteBuffer data = bbdst.buffer.duplicate();
 
             data.limit(dstIndex + length).position(dstIndex);
             getBytes(index, data);
         } else if (buffer.hasArray()) {
             dst.setBytes(dstIndex, buffer.array(), index + buffer.arrayOffset(), length);
         } else {
             dst.setBytes(dstIndex, this, index, length);
         }
     }
 
     public void getBytes(int index, byte[] dst, int dstIndex, int length) {
         ByteBuffer data = buffer.duplicate();
         try {
             data.limit(index + length).position(index);
         } catch (IllegalArgumentException e) {
             throw new IndexOutOfBoundsException("Too many bytes to read - Need "
                     + (index + length) + ", maximum is " + data.limit());
         }
         data.get(dst, dstIndex, length);
     }
 
     public void getBytes(int index, ByteBuffer dst) {
         ByteBuffer data = buffer.duplicate();
         int bytesToCopy = Math.min(capacity() - index, dst.remaining());
         try {
             data.limit(index + bytesToCopy).position(index);
         } catch (IllegalArgumentException e) {
             throw new IndexOutOfBoundsException("Too many bytes to read - Need "
                     + (index + bytesToCopy) + ", maximum is " + data.limit());
         }
         dst.put(data);
     }
 
     public void setByte(int index, int value) {
         buffer.put(index, (byte) value);
     }
 
     public void setShort(int index, int value) {
         buffer.putShort(index, (short) value);
     }
 
     public void setMedium(int index, int   value) {
         setByte(index,     (byte) (value >>> 16));
         setByte(index + 1, (byte) (value >>>  8));
         setByte(index + 2, (byte) value);
     }
 
     public void setInt(int index, int   value) {
         buffer.putInt(index, value);
     }
 
     public void setLong(int index, long  value) {
         buffer.putLong(index, value);
     }
 
     public void setBytes(int index, ChannelBuffer src, int srcIndex, int length) {
         if (src instanceof ByteBufferBackedChannelBuffer) {
             ByteBufferBackedChannelBuffer bbsrc = (ByteBufferBackedChannelBuffer) src;
             ByteBuffer data = bbsrc.buffer.duplicate();
 
             data.limit(srcIndex + length).position(srcIndex);
             setBytes(index, data);
         } else if (buffer.hasArray()) {
             src.getBytes(srcIndex, buffer.array(), index + buffer.arrayOffset(), length);
         } else {
             src.getBytes(srcIndex, this, index, length);
         }
     }
 
     public void setBytes(int index, byte[] src, int srcIndex, int length) {
         ByteBuffer data = buffer.duplicate();
         data.limit(index + length).position(index);
         data.put(src, srcIndex, length);
     }
 
     public void setBytes(int index, ByteBuffer src) {
         ByteBuffer data = buffer.duplicate();
         data.limit(index + src.remaining()).position(index);
         data.put(src);
     }
 
     public void getBytes(int index, OutputStream out, int length) throws IOException {
         if (length == 0) {
             return;
         }
 
         if (buffer.hasArray()) {
             out.write(
                     buffer.array(),
                     index + buffer.arrayOffset(),
                     length);
         } else {
             byte[] tmp = new byte[length];
             ((ByteBuffer) buffer.duplicate().position(index)).get(tmp);
             out.write(tmp);
         }
     }
 
     public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
         if (length == 0) {
             return 0;
         }
 
         return out.write((ByteBuffer) buffer.duplicate().position(index).limit(index + length));
     }
 
     public int setBytes(int index, InputStream in, int length)
             throws IOException {
 
         int readBytes = 0;
 
         if (buffer.hasArray()) {
             index += buffer.arrayOffset();
             do {
                 int localReadBytes = in.read(buffer.array(), index, length);
                 if (localReadBytes < 0) {
                     if (readBytes == 0) {
                         return -1;
                     } else {
                         break;
                     }
                 }
                 readBytes += localReadBytes;
                 index += localReadBytes;
                 length -= localReadBytes;
             } while (length > 0);
         } else {
             byte[] tmp = new byte[length];
             int i = 0;
             do {
                 int localReadBytes = in.read(tmp, i, tmp.length - i);
                 if (localReadBytes < 0) {
                     if (readBytes == 0) {
                         return -1;
                     } else {
                         break;
                     }
                 }
                 readBytes += localReadBytes;
                 i += readBytes;
             } while (i < tmp.length);
             ((ByteBuffer) buffer.duplicate().position(index)).put(tmp);
         }
 
         return readBytes;
     }
 
     public int setBytes(int index, ScatteringByteChannel in, int length)
             throws IOException {
 
         ByteBuffer slice = (ByteBuffer) buffer.duplicate().limit(index + length).position(index);
         int readBytes = 0;
 
         while (readBytes < length) {
             int localReadBytes;
             try {
                 localReadBytes = in.read(slice);
             } catch (ClosedChannelException e) {
                 localReadBytes = -1;
             }
             if (localReadBytes < 0) {
                 if (readBytes == 0) {
                     return -1;
                 } else {
                     return readBytes;
                 }
             } else if (localReadBytes == 0) {
                 break;
             }
             readBytes += localReadBytes;
         }
 
         return readBytes;
     }
 
     public ByteBuffer toByteBuffer(int index, int length) {
         if (index == 0 && length == capacity()) {
             return buffer.duplicate().order(order());
         } else {
             return ((ByteBuffer) buffer.duplicate().position(
                     index).limit(index + length)).slice().order(order());
         }
     }
 
     public ChannelBuffer slice(int index, int length) {
         if (index == 0 && length == capacity()) {
             ChannelBuffer slice = duplicate();
             slice.setIndex(0, length);
             return slice;
         } else {
             if (index >= 0 && length == 0) {
                 return ChannelBuffers.EMPTY_BUFFER;
             }
             return new ByteBufferBackedChannelBuffer(
                     ((ByteBuffer) buffer.duplicate().position(
                             index).limit(index + length)).order(order()));
         }
     }
 
     public ChannelBuffer duplicate() {
         return new ByteBufferBackedChannelBuffer(this);
     }
 
     public ChannelBuffer copy(int index, int length) {
         ByteBuffer src;
         try {
             src = (ByteBuffer) buffer.duplicate().position(index).limit(index + length);
         } catch (IllegalArgumentException e) {
             throw new IndexOutOfBoundsException("Too many bytes to read - Need "
                     + (index + length));
         }
 
         ByteBuffer dst = buffer.isDirect() ? ByteBuffer.allocateDirect(length) : ByteBuffer.allocate(length);
         dst.put(src);
         dst.order(order());
         dst.clear();
         return new ByteBufferBackedChannelBuffer(dst);
     }
 }