/*
   Copyright (c) 2016 James Ahlborn
   
   Licensed 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 com.healthmarketscience.jackcess.util;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.MappedByteBuffer;
  import java.nio.channels.FileChannel;
  import java.nio.channels.FileLock;
  import java.nio.channels.NonWritableChannelException;
  import java.nio.channels.ReadableByteChannel;
  import java.nio.channels.WritableByteChannel;
  import com.healthmarketscience.jackcess.Database;
  
  /**
   * Wrapper for existing FileChannel which is read-only.
   * <p>
   * Implementation note: this class is optimized for use with {@link Database}.
   * Therefore not all methods may be implemented.
   *
   * @author James Ahlborn
   * @usage _advanced_class_
   */
  public class ReadOnlyFileChannel extends FileChannel
  {
    private final FileChannel _delegate;
  
    public ReadOnlyFileChannel(FileChannel delegate) {
      _delegate = delegate;
    }
  
    @Override
    public int read(ByteBuffer dst) throws IOException {
      return _delegate.read(dst);
    }
  
    @Override
    public long read(ByteBuffer[] dsts, int offset, int length) throws IOException {
      return _delegate.read(dsts, offset, length);
    }
  
    @Override
    public int read(ByteBuffer dst, long position) throws IOException {
      return _delegate.read(dst, position);
    }
  
    @Override
    public long position() throws IOException {
      return _delegate.position();
    }
  
    @Override
    public FileChannel position(long newPosition) throws IOException {
      _delegate.position(newPosition);
      return this;
    }
  
    @Override
    public long size() throws IOException {
      return _delegate.size();
    }
  
    @Override
    public FileChannel truncate(long size) {
      throw new NonWritableChannelException();
    }
  
    @Override
    public void force(boolean metaData) {
      // do nothing
    }
  
    @Override
    public long transferTo(long position, long count, WritableByteChannel target)
      throws IOException
    {
      return _delegate.transferTo(position, count, target);
    }
  
    @Override
    public long transferFrom(ReadableByteChannel src, long position, long count)
    {
      throw new NonWritableChannelException();
    }
  
   @Override
   public int write(ByteBuffer src, long position) {
     throw new NonWritableChannelException();
   }
 
 
   @Override
   public int write(ByteBuffer src) {
     throw new NonWritableChannelException();
   }
 
   @Override
   public long write(ByteBuffer[] srcs, int offset, int length)
   {
     throw new NonWritableChannelException();
   }
 
   @Override
   public MappedByteBuffer map(MapMode mode, long position, long size)
   {
     throw new UnsupportedOperationException();
   }
 
   @Override
   public FileLock lock(long position, long size, boolean shared)
   {
     throw new UnsupportedOperationException();
   }
 
   @Override
   public FileLock tryLock(long position, long size, boolean shared)
   {
     throw new UnsupportedOperationException();
   }
 
   @Override
   protected void implCloseChannel() throws IOException {
     _delegate.close();
   }
 }