/*

 * Copyright (C) 2009 The Sipdroid Open Source Project

 * Copyright (C) 2005 Luca Veltri - University of Parma - Italy

 * 

 * This file is part of Sipdroid (http://www.sipdroid.org)

 * 

 * Sipdroid is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 3 of the License, or

 * (at your option) any later version.

 * 

 * This source code 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 General Public License for more details.

 * 

 * You should have received a copy of the GNU General Public License

 * along with this source code; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package src.org.sipdroid.net;

import org.zoolu.tools.Random;

/**

 * RtpPacket implements a RTP packet.

 */

public class RtpPacket {

	/* RTP packet buffer containing both the RTP header and payload */

	byte[] packet;

	/* RTP packet length */

	int packet_len;

	/* RTP header length */

	// int header_len;

	/** Gets the RTP packet */

	public byte[] getPacket() {

		return packet;

	}

	/** Gets the RTP packet length */

	public int getLength() {

		return packet_len;

	}

	/** Gets the RTP header length */

	public int getHeaderLength() {

		if (packet_len >= 12)

			return 12 + 4 * getCscrCount();

		else

			return packet_len; // broken packet

	}

	/** Gets the RTP header length */

	public int getPayloadLength() {

		if (packet_len >= 12)

			return packet_len - getHeaderLength();

		else

			return 0; // broken packet

	}

	/** Sets the RTP payload length */

	public void setPayloadLength(int len) {

		packet_len = getHeaderLength() + len;

	}

	// version (V): 2 bits

	// padding (P): 1 bit

	// extension (X): 1 bit

	// CSRC count (CC): 4 bits

	// marker (M): 1 bit

	// payload type (PT): 7 bits

	// sequence number: 16 bits

	// timestamp: 32 bits

	// SSRC: 32 bits

	// CSRC list: 0 to 15 items, 32 bits each

	/** Gets the version (V) */

	public int getVersion() {

		if (packet_len >= 12)

			return (packet[0] >> 6 & 0x03);

		else

			return 0; // broken packet

	}

	/** Sets the version (V) */

	public void setVersion(int v) {

		if (packet_len >= 12)

			packet[0] = (byte) ((packet[0] & 0x3F) | ((v & 0x03) << 6));

	}

	/** Whether has padding (P) */

	public boolean hasPadding() {

		if (packet_len >= 12)

			return getBit(packet[0], 5);

		else

			return false; // broken packet

	}

	/** Set padding (P) */

	public void setPadding(boolean p) {

		if (packet_len >= 12)

			packet[0] = setBit(p, packet[0], 5);

	}

	/** Whether has extension (X) */

	public boolean hasExtension() {

		if (packet_len >= 12)

			return getBit(packet[0], 4);

		else

			return false; // broken packet

	}

	/** Set extension (X) */

	public void setExtension(boolean x) {

		if (packet_len >= 12)

			packet[0] = setBit(x, packet[0], 4);

	}

	/** Gets the CSCR count (CC) */

	public int getCscrCount() {

		if (packet_len >= 12)

			return (packet[0] & 0x0F);

		else

			return 0; // broken packet

	}

	/** Whether has marker (M) */

	public boolean hasMarker() {

		if (packet_len >= 12)

			return getBit(packet[1], 7);

		else

			return false; // broken packet

	}

	/** Set marker (M) */

	public void setMarker(boolean m) {

		if (packet_len >= 12)

			packet[1] = setBit(m, packet[1], 7);

	}

	/** Gets the payload type (PT) */

	public int getPayloadType() {

		if (packet_len >= 12)

			return (packet[1] & 0x7F);

		else

			return -1; // broken packet

	}

	/** Sets the payload type (PT) */

	public void setPayloadType(int pt) {

		if (packet_len >= 12)

			packet[1] = (byte) ((packet[1] & 0x80) | (pt & 0x7F));

	}

	/** Gets the sequence number */

	public int getSequenceNumber() {

		if (packet_len >= 12)

			return getInt(packet, 2, 4);

		else

			return 0; // broken packet

	}

	/** Sets the sequence number */

	public void setSequenceNumber(int sn) {

		if (packet_len >= 12)

			setInt(sn, packet, 2, 4);

	}

	/** Gets the timestamp */

	public long getTimestamp() {

		if (packet_len >= 12)

			return getLong(packet, 4, 8);

		else

			return 0; // broken packet

	}

	/** Sets the timestamp */

	public void setTimestamp(long timestamp) {

		if (packet_len >= 12)

			setLong(timestamp, packet, 4, 8);

	}

	/** Gets the SSCR */

	public long getSscr() {

		if (packet_len >= 12)

			return getLong(packet, 8, 12);

		else

			return 0; // broken packet

	}

	/** Sets the SSCR */

	public void setSscr(long ssrc) {

		if (packet_len >= 12)

			setLong(ssrc, packet, 8, 12);

	}

	/** Gets the CSCR list */

	public long[] getCscrList() {

		int cc = getCscrCount();

		long[] cscr = new long[cc];

		for (int i = 0; i < cc; i++)

			cscr[i] = getLong(packet, 12 + 4 * i, 16 + 4 * i);

		return cscr;

	}

	/** Sets the CSCR list */

	public void setCscrList(long[] cscr) {

		if (packet_len >= 12) {

			int cc = cscr.length;

			if (cc > 15)

				cc = 15;

			packet[0] = (byte) (((packet[0] >> 4) << 4) + cc);

			cscr = new long[cc];

			for (int i = 0; i < cc; i++)

				setLong(cscr[i], packet, 12 + 4 * i, 16 + 4 * i);

			// header_len=12+4*cc;

		}

	}

	/** Sets the payload */

	public void setPayload(byte[] payload, int len) {

		if (packet_len >= 12) {

			int header_len = getHeaderLength();

			for (int i = 0; i < len; i++)

				packet[header_len + i] = payload[i];

			packet_len = header_len + len;

		}

	}

	/** Gets the payload */

	public byte[] getPayload() {

		int header_len = getHeaderLength();

		int len = packet_len - header_len;

		byte[] payload = new byte[len];

		for (int i = 0; i < len; i++)

			payload[i] = packet[header_len + i];

		return payload;

	}

	/** Creates a new RTP packet */

	public RtpPacket(byte[] buffer, int packet_length) {

		packet = buffer;

		packet_len = packet_length;

		if (packet_len < 12)

			packet_len = 12;

		init(0x0F);

	}

	/** init the RTP packet header (only PT) */

	public void init(int ptype) {

		init(ptype, Random.nextLong());

	}

	/** init the RTP packet header (PT and SSCR) */

	public void init(int ptype, long sscr) {

		init(ptype, Random.nextInt(), Random.nextLong(), sscr);

	}

	/** init the RTP packet header (PT, SQN, TimeStamp, SSCR) */

	public void init(int ptype, int seqn, long timestamp, long sscr) {

		setVersion(2);

		setPayloadType(ptype);

		setSequenceNumber(seqn);

		setTimestamp(timestamp);

		setSscr(sscr);

	}

	// *********************** Private and Static ***********************

	/** Gets int value */

	private static int getInt(byte b) {

		return ((int) b + 256) % 256;

	}

	/** Gets long value */

	private static long getLong(byte[] data, int begin, int end) {

		long n = 0;

		for (; begin < end; begin++) {

			n <<= 8;

			n += data[begin];

		}

		return n;

	}

	/** Sets long value */

	private static void setLong(long n, byte[] data, int begin, int end) {

		for (end--; end >= begin; end--) {

			data[end] = (byte) (n % 256);

			n >>= 8;

		}

	}

	/** Gets Int value */

	private static int getInt(byte[] data, int begin, int end) {

		return (int) getLong(data, begin, end);

	}

	/** Sets Int value */

	private static void setInt(int n, byte[] data, int begin, int end) {

		setLong(n, data, begin, end);

	}

	/** Gets bit value */

	private static boolean getBit(byte b, int bit) {

		return (b >> bit) == 1;

	}

	/** Sets bit value */

	private static byte setBit(boolean value, byte b, int bit) {

		if (value)

			return (byte) (b | (1 << bit));

		else

			return (byte) ((b | (1 << bit)) ^ (1 << bit));

	}

}