/**
 * Copyright 2007-2016, Kaazing Corporation. All rights reserved.
 *
 * 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 org.apache.mina.core.file;

import java.io.IOException;
import java.nio.channels.FileChannel;


/**
 * TODO Add documentation
 * 
 * 
 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
 */
public class DefaultFileRegion implements FileRegion {

    private final FileChannel channel;

    private final long originalPosition;
    private long position;
    private long remainingBytes;

    public DefaultFileRegion(FileChannel channel) throws IOException {
        this(channel, 0, channel.size());
    }
    
    public DefaultFileRegion(FileChannel channel, long position, long remainingBytes) {
        if (channel == null) {
            throw new IllegalArgumentException("channel can not be null");
        }
        if (position < 0) {
            throw new IllegalArgumentException("position may not be less than 0");
        }
        if (remainingBytes < 0) {
            throw new IllegalArgumentException("remainingBytes may not be less than 0");
        }
        this.channel = channel;
        this.originalPosition = position;
        this.position = position;
        this.remainingBytes = remainingBytes;
    }

    public long getWrittenBytes() {
        return position - originalPosition;
    }

    public long getRemainingBytes() {
        return remainingBytes;
    }

    public FileChannel getFileChannel() {
        return channel;
    }

    public long getPosition() {
        return position;
    }

    public void update(long value) {
        position += value;
        remainingBytes -= value;
    }

}
