/*
    * 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.channels.ClosedChannelException;
  import java.nio.channels.GatheringByteChannel;
  import java.nio.channels.ScatteringByteChannel;
  
  /**
   * A skeletal implementation for Java heap buffers.
   */
  public abstract class HeapChannelBuffer extends AbstractChannelBuffer {
  
      /**
       * The underlying heap byte array that this buffer is wrapping.
       */
      protected final byte[] array;
  
      /**
       * Creates a new heap buffer with a newly allocated byte array.
       *
       * @param length the length of the new byte array
       */
      protected HeapChannelBuffer(int length) {
          this(new byte[length], 0, 0);
      }
  
      /**
       * Creates a new heap buffer with an existing byte array.
       *
       * @param array the byte array to wrap
       */
      protected HeapChannelBuffer(byte[] array) {
          this(array, 0, array.length);
      }
  
      /**
       * Creates a new heap buffer with an existing byte array.
       *
       * @param array        the byte array to wrap
       * @param readerIndex  the initial reader index of this buffer
       * @param writerIndex  the initial writer index of this buffer
       */
      protected HeapChannelBuffer(byte[] array, int readerIndex, int writerIndex) {
          if (array == null) {
              throw new NullPointerException("array");
          }
          this.array = array;
          setIndex(readerIndex, writerIndex);
      }
  
      public boolean isDirect() {
          return false;
      }
  
      public int capacity() {
          return array.length;
      }
  
      public boolean hasArray() {
          return true;
      }
  
      public byte[] array() {
          return array;
      }
  
      public int arrayOffset() {
          return 0;
      }
  
      public byte getByte(int index) {
          return array[index];
      }
  
      public void getBytes(int index, ChannelBuffer dst, int dstIndex, int length) {
          if (dst instanceof HeapChannelBuffer) {
              getBytes(index, ((HeapChannelBuffer) dst).array, dstIndex, length);
          } else {
              dst.setBytes(dstIndex, array, index, length);
          }
      }
 
     public void getBytes(int index, byte[] dst, int dstIndex, int length) {
         System.arraycopy(array, index, dst, dstIndex, length);
     }
 
     public void getBytes(int index, ByteBuffer dst) {
         dst.put(array, index, Math.min(capacity() - index, dst.remaining()));
     }
 
     public void getBytes(int index, OutputStream out, int length)
             throws IOException {
         out.write(array, index, length);
     }
 
     public int getBytes(int index, GatheringByteChannel out, int length)
             throws IOException {
         return out.write(ByteBuffer.wrap(array, index, length));
     }
 
     public void setByte(int index, int value) {
         array[index] = (byte) value;
     }
 
     public void setBytes(int index, ChannelBuffer src, int srcIndex, int length) {
         if (src instanceof HeapChannelBuffer) {
             setBytes(index, ((HeapChannelBuffer) src).array, srcIndex, length);
         } else {
             src.getBytes(srcIndex, array, index, length);
         }
     }
 
     public void setBytes(int index, byte[] src, int srcIndex, int length) {
         System.arraycopy(src, srcIndex, array, index, length);
     }
 
     public void setBytes(int index, ByteBuffer src) {
         src.get(array, index, src.remaining());
     }
 
     public int setBytes(int index, InputStream in, int length) throws IOException {
         int readBytes = 0;
         do {
             int localReadBytes = in.read(array, index, length);
             if (localReadBytes < 0) {
                 if (readBytes == 0) {
                     return -1;
                 } else {
                     break;
                 }
             }
             readBytes += localReadBytes;
             index += localReadBytes;
             length -= localReadBytes;
         } while (length > 0);
 
         return readBytes;
     }
 
     public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
         ByteBuffer buf = ByteBuffer.wrap(array, index, length);
         int readBytes = 0;
 
         do {
             int localReadBytes;
             try {
                 localReadBytes = in.read(buf);
             } catch (ClosedChannelException e) {
                 localReadBytes = -1;
             }
             if (localReadBytes < 0) {
                 if (readBytes == 0) {
                     return -1;
                 } else {
                     break;
                 }
             } else if (localReadBytes == 0) {
                 break;
             }
             readBytes += localReadBytes;
         } while (readBytes < length);
 
         return readBytes;
     }
 
     public ChannelBuffer slice(int index, int length) {
         if (index == 0) {
             if (length == 0) {
                 return ChannelBuffers.EMPTY_BUFFER;
             }
             if (length == array.length) {
                 ChannelBuffer slice = duplicate();
                 slice.setIndex(0, length);
                 return slice;
             } else {
                 return new TruncatedChannelBuffer(this, length);
             }
         } else {
             if (length == 0) {
                 return ChannelBuffers.EMPTY_BUFFER;
             }
             return new SlicedChannelBuffer(this, index, length);
         }
     }
 
     public ByteBuffer toByteBuffer(int index, int length) {
         return ByteBuffer.wrap(array, index, length).order(order());
     }
 }