package org.red5.io.mp4;

/*
 * RED5 Open Source Flash Server - http://code.google.com/p/red5/
 * 
 * Copyright (c) 2006-2007 by respective authors (see below). All rights reserved.
 * 
 * This library is free software; you can redistribute it and/or modify it under the 
 * terms of the GNU Lesser General Public License as published by the Free Software 
 * Foundation; either version 2.1 of the License, or (at your option) any later 
 * version. 
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY 
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A 
 * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License along 
 * with this library; if not, write to the Free Software Foundation, Inc., 
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
 */

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

/**
 * Wrapper class for input streams containing MPEG4 data.
 * 
 * Original idea based on code from MediaFrame (http://www.mediaframe.org)
 * 
 * @author Paul Gregoire (mondain@gmail.com)
 */
public final class MP4DataStream {

	/** The input stream. */
	private FileInputStream is;

	/** The current offset (position) in the stream. */
	private long offset = 0;

	/**
	 * Constructs an <code>MP4DataStream</code> object using the specified
	 * MPEG4 input stream.
	 * 
	 * @param is
	 *            the MPEG4 input stream.
	 */
	public MP4DataStream(FileInputStream is) {
		this.is = is;
	}

	public long readBytes(int n) throws IOException {
		int c = -1;
		long result = 0;
		while ((n-- > 0) && ((c = is.read()) != -1)) {
			result <<= 8;
			result += c & 0xff;
			offset++;
		}
		if (c == -1) {
			throw new EOFException();
		}
		return result;
	}

	public String readString(int n) throws IOException {
		char c = (char) -1;
		StringBuilder sb = new StringBuilder();
		while ((n-- > 0) && ((c = (char) is.read()) != -1)) {
			sb.append(c);
			offset++;
		}
		if (c == -1) {
			throw new EOFException();
		}
		return sb.toString();
	}

	public void skipBytes(long n) throws IOException {
		offset += n;
		is.skip(n);
	}

	public long getOffset() {
		return offset;
	}

	public FileChannel getChannel() {
		return is.getChannel();
	}

	public void close() throws IOException {
		is.close();
	}
}