/**

 * 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;

/**

 * RTCP packets for RTP Feedback Messages 

 * 

 * In line with RFC 4585, this packet currently only supports NACKs

 * 

 * @author Arne Kepp

 */

public class RtcpPktRTPFB extends RtcpPkt {

	/** If this packet was for a different SSRC */

	protected boolean notRelevant = false;

	/** SSRC we are sending feeback to */

	protected long ssrcMediaSource = -1;

	/** RTP sequence numbers of lost packets */

	protected int PID[];

	/** bitmask of following lost packets, shared index with PID */

	protected int BLP[];

	/**

	 * Constructor for RTP Feedback Message

	 * 

	 * @param ssrcPacketSender SSRC of sender, taken from RTPSession

	 * @param ssrcMediaSource SSRC of recipient of this message

	 * @param FMT the Feedback Message Subtype

	 * @param PID RTP sequence numbers of lost packets

	 * @param BLP bitmask of following lost packets, shared index with PID 

	 */

	protected RtcpPktRTPFB(long ssrcPacketSender, long ssrcMediaSource, int FMT, int[] PID, int[] BLP) {

		super.packetType = 205; //RTPFB

		super.itemCount = FMT; 

		this.PID = PID;

		this.BLP = BLP;

	}

	/**

	 * Constructor that parses a raw packet to retrieve information

	 * 

	 * @param aRawPkt the raw packet to be parsed

	 * @param start the start of the packet, in bytes

	 * @param rtpSession the session on which the callback interface resides

	 */

	protected RtcpPktRTPFB(byte[] aRawPkt, int start, RTPSession rtpSession) {		

		if(RTPSession.rtpDebugLevel > 8) {

			System.out.println("  -> RtcpPktRTPFB(byte[], int start)");

		}

		rawPkt = aRawPkt;

		if(! super.parseHeaders(start) || packetType != 205 || super.length < 2) {

			if(RTPSession.rtpDebugLevel > 2) {

				System.out.println(" <-> RtcpPktRTPFB.parseHeaders() etc. problem");

			}

			super.problem = -205;

		} else {

			//FMT = super.itemCount;

			ssrcMediaSource = StaticProcs.bytesToUIntLong(aRawPkt,8+start);

			if(ssrcMediaSource == rtpSession.ssrc) {

				super.ssrc = StaticProcs.bytesToUIntLong(aRawPkt,4+start);

				int loopStop = super.length - 2;

				PID = new int[loopStop];

				BLP = new int[loopStop];

				int curStart = 12;

				// Loop over Feedback Control Information (FCI) fields

				for(int i=0; i< loopStop; i++) {

					PID[i] = StaticProcs.bytesToUIntInt(aRawPkt, curStart);

					BLP[i] = StaticProcs.bytesToUIntInt(aRawPkt, curStart + 2);

					curStart += 4;

				}

				rtpSession.rtcpAVPFIntf.RTPFBPktReceived(

						super.ssrc, super.itemCount, PID, BLP);

			}

		}

		if(RTPSession.rtpDebugLevel > 8) {

			System.out.println("  <- RtcpPktRTPFB()");

		}

	}

	/**

	 * Encode the packet into a byte[], saved in .rawPkt

	 * 

	 * CompRtcpPkt will call this automatically

	 */

	protected void encode() {

		super.rawPkt = new byte[12 + this.PID.length*4];

		byte[] someBytes = StaticProcs.uIntLongToByteWord(super.ssrc);

		System.arraycopy(someBytes, 0, super.rawPkt, 4, 4);

		someBytes = StaticProcs.uIntLongToByteWord(this.ssrcMediaSource);

		System.arraycopy(someBytes, 0, super.rawPkt, 8, 4);

		// Loop over Feedback Control Information (FCI) fields

		int curStart = 12;

		for(int i=0; i < this.PID.length; i++ ) {

			someBytes = StaticProcs.uIntIntToByteWord(PID[i]);

			super.rawPkt[curStart++] = someBytes[0];

			super.rawPkt[curStart++] = someBytes[1];

			someBytes = StaticProcs.uIntIntToByteWord(BLP[i]);

			super.rawPkt[curStart++] = someBytes[0];

			super.rawPkt[curStart++] = someBytes[1];

		}

		writeHeaders();

	}

	/** 

	 * Get the FMT (Feedback Message Type)

	 * @return value stored in .itemcount, same field

	 */

	protected int getFMT() {

		return this.itemCount;

	}

	/**

	 * Debug purposes only

	 */

	protected void debugPrint() {

		System.out.println("->RtcpPktRTPFB.debugPrint() ");

		System.out.println("  ssrcPacketSender: " + super.ssrc + "  ssrcMediaSource: " + ssrcMediaSource);

		if(this.PID != null && this.PID.length < 1) {

			System.out.println("  No Feedback Control Information (FCI) fields");

		}

		for(int i=0; i < this.PID.length; i++ ) {

			System.out.println("  FCI -> PID: " + PID[i] + "  BLP: " + BLP[i]);

		}

		System.out.println("<-RtcpPktRTPFB.debugPrint() ");

	}

}