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//
//  ========================================================================
//  Copyright (c) 1995-2016 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.io.nio;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
import java.nio.channels.WritableByteChannel;

import org.eclipse.jetty.io.AbstractBuffer;
import org.eclipse.jetty.io.Buffer;

public class RandomAccessFileBuffer extends AbstractBuffer implements Buffer
{
    final RandomAccessFile _file;
    final FileChannel _channel;
    final int _capacity;

    public RandomAccessFileBuffer(File file) 
        throws FileNotFoundException
    {
        super(READWRITE,true);
        assert file.length()<=Integer.MAX_VALUE;
        _file = new RandomAccessFile(file,"rw");
        _channel=_file.getChannel();
        _capacity=Integer.MAX_VALUE;
        setGetIndex(0);
        setPutIndex((int)file.length());
    }
    
    public RandomAccessFileBuffer(File file,int capacity) 
        throws FileNotFoundException
    {
        super(READWRITE,true);
        assert capacity>=file.length();
        assert file.length()<=Integer.MAX_VALUE;
        _capacity=capacity;
        _file = new RandomAccessFile(file,"rw");
        _channel=_file.getChannel();
        setGetIndex(0);
        setPutIndex((int)file.length());
    }
    
    public RandomAccessFileBuffer(File file,int capacity,int access) 
        throws FileNotFoundException
    {
        super(access,true);
        assert capacity>=file.length();
        assert file.length()<=Integer.MAX_VALUE;
        _capacity=capacity;
        _file = new RandomAccessFile(file,access==READWRITE?"rw":"r");
        _channel=_file.getChannel();
        setGetIndex(0);
        setPutIndex((int)file.length());
    }

    public byte[] array()
    {
        return null;
    }

    public int capacity()
    {
        return _capacity;
    }

    @Override
    public void clear()
    {
        try
        {
            synchronized (_file)
            {
                super.clear();
                _file.setLength(0);
            }
        }
        catch(Exception e)
        {
            throw new RuntimeException(e);
        }
    }


    @Override
    public byte peek()
    {
        synchronized (_file)
        {
            try
            {
                if (_get!=_file.getFilePointer())
                    _file.seek(_get);
                return _file.readByte();
            }
            catch(Exception e)
            {
                throw new RuntimeException(e);
            }
        }
    }

    public byte peek(int index)
    {
        synchronized (_file)
        {
            try
            {
                _file.seek(index);
                return _file.readByte();
            }
            catch(Exception e)
            {
                throw new RuntimeException(e);
            }
        }
    }

    public int peek(int index, byte[] b, int offset, int length)
    {
        synchronized (_file)
        {
            try
            {
                _file.seek(index);
                return _file.read(b,offset,length);
            }
            catch(Exception e)
            {
                throw new RuntimeException(e);
            }
        }
    }

    public void poke(int index, byte b)
    {
        synchronized (_file)
        {
            try
            {
                _file.seek(index);
                _file.writeByte(b);
            }
            catch(Exception e)
            {
                throw new RuntimeException(e);
            }
        }
    }

    @Override
    public int poke(int index, byte[] b, int offset, int length)
    {
        synchronized (_file)
        {
            try
            {
                _file.seek(index);
                _file.write(b,offset,length);
                return length;
            }
            catch(Exception e)
            {
                throw new RuntimeException(e);
            }
        }
    }
    
    public int writeTo(WritableByteChannel channel,int index, int length)
        throws IOException
    {
        synchronized (_file)
        {
            return (int)_channel.transferTo(index,length,channel);
        }
    }
    
}