/**

 * Java RTP Library (jlibrtp)

 * Copyright (C) 2006 Arne Kepp

 * 

 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 */

package jlibrtp;

import java.net.InetAddress;

/** 

 * Common RTCP packet headers.

 *

 * @author Arne Kepp

 */

public class RtcpPkt {

	/** Whether a problem has been encountered during parsing */

	protected int problem = 0;

	/** The version, always 2, 2 bits */

	protected int version = 2;

	/** Padding , 1 bit */

	protected int padding = 0;

	/** Number of items, e.g. receiver report blocks. Usage may vary. 5 bits */

	protected int itemCount = 0;

	/** The type of RTCP packet, 8 bits */

	protected int packetType = -1;

	/** The length of the RTCP packet, in 32 bit blocks minus 1. 16 bits*/

	protected int length = -1;

	/** The ssrc that sent this, usually dictated by RTP Session */

	protected long ssrc = -1;

	/** Contains the actual data (eventually) */

	protected byte[] rawPkt = null;

	/** Only used for feedback messages: Time message was generated */

	protected long time = -1;

	/** Only used for feedback message: Whether this packet was received */

	protected boolean received = false;

	/**

	 * Parses the common header of an RTCP packet

	 * 

	 * @param start where in this.rawPkt the headers start

	 * @return true if parsing succeeded and header cheks 

	 */

	protected boolean parseHeaders(int start) {

		version = ((rawPkt[start+0] & 0xC0) >>> 6);

		padding = ((rawPkt[start+0] & 0x20) >>> 5);

		itemCount = (rawPkt[start+0] & 0x1F);

		packetType = (int) rawPkt[start+1];

		if(packetType < 0) {

			packetType += 256;

		}

		length = StaticProcs.bytesToUIntInt(rawPkt, start+2);

		if(RTPSession.rtpDebugLevel > 9) {

			System.out.println(" <-> RtcpPkt.parseHeaders() version:"+version+" padding:"+padding+" itemCount:"+itemCount

					+" packetType:"+packetType+" length:"+length);

		}

		if(packetType > 207 || packetType < 200) 

			System.out.println("RtcpPkt.parseHeaders problem discovered, packetType " + packetType);

		if(version == 2 && length < 65536) {

			return true;

		} else {

			System.out.println("RtcpPkt.parseHeaders() failed header checks, check size and version");

			this.problem = -1;

			return false;

		}

	}

	/**

	 * Writes the common header of RTCP packets. 

	 * The values should be filled in when the packet is initiliazed and this function

	 * called at the very end of .encode()

	 */

	protected void writeHeaders() {

		byte aByte = 0;

		aByte |=(version << 6);

		aByte |=(padding << 5);

		aByte |=(itemCount);

		rawPkt[0] = aByte;

		aByte = 0;

		aByte |= packetType;

		rawPkt[1] = aByte;

		if(rawPkt.length % 4 != 0)

			System.out.println("!!!! RtcpPkt.writeHeaders() rawPkt was not a multiple of 32 bits / 4 octets!");

		byte[] someBytes = StaticProcs.uIntIntToByteWord((rawPkt.length / 4) - 1);

		rawPkt[2] = someBytes[0];

		rawPkt[3] = someBytes[1];

	}

	/**

	 * This is just a dummy to make Eclipse complain less.

	 */

	protected void encode() {

		System.out.println("RtcpPkt.encode() should never be invoked!! " + this.packetType);

	}

	/**

	 * Check whether this packet came from the source we expected.

	 * 

	 * Not currently used!

	 * 

	 * @param adr address that packet came from

	 * @param partDb the participant database for the session

	 * @return true if this packet came from the expected source

	 */

	protected boolean check(InetAddress adr, ParticipantDatabase partDb) {

		//Multicast -> We have to be naive

		if (partDb.rtpSession.mcSession && adr.equals(partDb.rtpSession.mcGroup))

			return true;

		//See whether this participant is known

		Participant part = partDb.getParticipant(this.ssrc);

		if(part != null && part.rtcpAddress.getAddress().equals(adr))

			return true;

		//If not, we should look for someone without SSRC with his ip-address?

		return false;

	}

}