/**
 * 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.InetSocketAddress;

/**
 * A participant represents a peer in an RTPSession. Based on the information
 * stored on these objects, packets are processed and statistics generated for
 * RTCP.
 */
public class Participant {
	/**
	 * Whether the participant is unexpected, e.g. arrived through unicast with
	 * SDES
	 */
	protected boolean unexpected = false;
	/** Where to send RTP packets (unicast) */
	protected InetSocketAddress rtpAddress = null;
	/** Where to send RTCP packets (unicast) */
	protected InetSocketAddress rtcpAddress = null;
	/** Where the first RTP packet was received from */
	protected InetSocketAddress rtpReceivedFromAddress = null;
	/** Where the first RTCP packet was received from */
	protected InetSocketAddress rtcpReceivedFromAddress = null;

	/** SSRC of participant */
	protected long ssrc = -1;
	/** SDES CNAME */
	protected String cname = null;
	/** SDES The participant's real name */
	protected String name = null;
	/** SDES The participant's email */
	protected String email = null;
	/** SDES The participant's phone number */
	protected String phone = null;
	/** SDES The participant's location */
	protected String loc = null;
	/** SDES The tool the participants is using */
	protected String tool = null;
	/** SDES A note */
	protected String note = null;
	/** SDES A priv string, loosely defined */
	protected String priv = null;

	// Receiver Report Items
	/** RR First sequence number */
	protected int firstSeqNumber = -1;
	/** RR Last sequence number */
	protected int lastSeqNumber = 0;
	/** RR Number of times sequence number has rolled over */
	protected long seqRollOverCount = 0;
	/** RR Number of packets received */
	protected long receivedPkts = 0;
	/** RR Number of octets received */
	protected long receivedOctets = 0;
	/** RR Number of packets received since last SR */
	protected int receivedSinceLastSR = 0;
	/** RR Sequence number associated with last SR */
	protected int lastSRRseqNumber = 0;
	/** RR Interarrival jitter */
	protected double interArrivalJitter = -1.0;
	/** RR Last received RTP Timestamp */
	protected long lastRtpTimestamp = 0;

	/** RR Middle 32 bits of the NTP timestamp in the last SR */
	protected long timeStampLSR = 0;
	/** RR The time when we actually got the last SR */
	protected long timeReceivedLSR = 0;

	/** Gradient where UNIX timestamp = ntpGradient*RTPTimestamp * ntpOffset */
	protected double ntpGradient = -1;
	/** Offset where UNIX timestamp = ntpGradient*RTPTimestamp * ntpOffset */
	protected long ntpOffset = -1;
	/** Last NTP received in SR packet, MSB */
	protected long lastNtpTs1 = 0; // 32 bits
	/** Last NTP received in SR packet, LSB */
	protected long lastNtpTs2 = 0; // 32 bits
	/** RTP Timestamp in last SR packet */
	protected long lastSRRtpTs = 0; // 32 bits

	/** UNIX time when a BYE was received from this participant, for pruning */
	protected long timestampBYE = -1; // The user said BYE at this time

	/** Store the packets received from this participant */
	protected PktBuffer pktBuffer = null;

	/**
	 * UNIX time of last RTP packet, to check whether this participant has sent
	 * anything recently
	 */
	protected long lastRtpPkt = -1; // Time of last RTP packet
	/**
	 * UNIX time of last RTCP packet, to check whether this participant has sent
	 * anything recently
	 */
	protected long lastRtcpPkt = -1; // Time of last RTCP packet
	/**
	 * UNIX time this participant was added by application, to check whether we
	 * ever heard back
	 */
	protected long addedByApp = -1; // Time the participant was added by
									// application
	/** UNIX time of last time we sent an RR to this user */
	protected long lastRtcpRRPkt = -1; // Timestamp of last time we sent this
										// person an RR packet
	/** Unix time of second to last time we sent and RR to this user */
	protected long secondLastRtcpRRPkt = -1; // Timestamp of 2nd to last time we
												// sent this person an RR Packet

	/**
	 * Create a basic participant. If this is a <b>unicast</b> session you must
	 * provide network address (ipv4 or ipv6) and ports for RTP and RTCP, as
	 * well as a cname for this contact. These things should be negotiated
	 * through SIP or a similar protocol.
	 * 
	 * jlibrtp will listen for RTCP packets to obtain a matching SSRC for this
	 * participant, based on cname.
	 * 
	 * @param networkAddress
	 *            string representation of network address (ipv4 or ipv6). Use
	 *            "127.0.0.1" for multicast session.
	 * @param rtpPort
	 *            port on which peer expects RTP packets. Use 0 if this is a
	 *            sender-only, or this is a multicast session.
	 * @param rtcpPort
	 *            port on which peer expects RTCP packets. Use 0 if this is a
	 *            sender-only, or this is a multicast session.
	 */
	public Participant(String networkAddress, int rtpPort, int rtcpPort) {
		if (RTPSession.rtpDebugLevel > 6) {
			System.out.println("Creating new participant: " + networkAddress);
		}

		// RTP
		if (rtpPort > 0) {
			try {
				rtpAddress = new InetSocketAddress(networkAddress, rtpPort);
			} catch (Exception e) {
				System.out.println("Couldn't resolve " + networkAddress);
			}
			// isReceiver = true;
		}

		// RTCP
		if (rtcpPort > 0) {
			try {
				rtcpAddress = new InetSocketAddress(networkAddress, rtcpPort);
			} catch (Exception e) {
				System.out.println("Couldn't resolve " + networkAddress);
			}
		}

		// By default this is a sender
		// isSender = true;
	}

	// We got a packet, but we don't know this person yet.
	protected Participant(InetSocketAddress rtpAdr, InetSocketAddress rtcpAdr,
			long SSRC) {
		rtpReceivedFromAddress = rtpAdr;
		rtcpReceivedFromAddress = rtcpAdr;
		ssrc = SSRC;
		unexpected = true;
	}

	// Dummy constructor to ease testing
	protected Participant() {
		System.out.println("Don't use the Participan(void) Constructor!");
	}

	/**
	 * RTP Address registered with this participant.
	 * 
	 * @return address of participant
	 */
	InetSocketAddress getRtpSocketAddress() {
		return rtpAddress;
	}

	/**
	 * RTCP Address registered with this participant.
	 * 
	 * @return address of participant
	 */
	InetSocketAddress getRtcpSocketAddress() {
		return rtcpAddress;
	}

	/**
	 * InetSocketAddress this participant has used to send us RTP packets.
	 * 
	 * @return address of participant
	 */
	InetSocketAddress getRtpReceivedFromAddress() {
		return rtpAddress;
	}

	/**
	 * InetSocketAddress this participant has used to send us RTCP packets.
	 * 
	 * @return address of participant
	 */
	InetSocketAddress getRtcpReceivedFromAddress() {
		return rtcpAddress;
	}

	/**
	 * CNAME registered for this participant.
	 * 
	 * @return the cname
	 */
	public String getCNAME() {
		return cname;
	}

	/**
	 * NAME registered for this participant.
	 * 
	 * @return the name
	 */
	public String getNAME() {
		return name;
	}

	/**
	 * EMAIL registered for this participant.
	 * 
	 * @return the email address
	 */
	public String getEmail() {
		return email;
	}

	/**
	 * PHONE registered for this participant.
	 * 
	 * @return the phone number
	 */
	public String getPhone() {
		return phone;
	}

	/**
	 * LOCATION registered for this participant.
	 * 
	 * @return the location
	 */
	public String getLocation() {
		return loc;
	}

	/**
	 * NOTE registered for this participant.
	 * 
	 * @return the note
	 */
	public String getNote() {
		return note;
	}

	/**
	 * PRIVATE something registered for this participant.
	 * 
	 * @return the private-string
	 */
	public String getPriv() {
		return priv;
	}

	/**
	 * TOOL something registered for this participant.
	 * 
	 * @return the tool
	 */
	public String getTool() {
		return tool;
	}

	/**
	 * SSRC for participant, determined through RTCP SDES
	 * 
	 * @return SSRC (32 bit unsigned integer as long)
	 */
	public long getSSRC() {
		return this.ssrc;
	}

	/**
	 * Updates the participant with information for receiver reports.
	 * 
	 * @param packetLength
	 *            to keep track of received octets
	 * @param pkt
	 *            the most recently received packet
	 */
	protected void updateRRStats(int packetLength, RtpPkt pkt) {
		int curSeqNum = pkt.getSeqNumber();

		if (firstSeqNumber < 0) {
			firstSeqNumber = curSeqNum;
		}

		receivedOctets += packetLength;
		receivedSinceLastSR++;
		receivedPkts++;

		long curTime = System.currentTimeMillis();

		if (this.lastSeqNumber < curSeqNum) {
			// In-line packet, best thing you could hope for
			this.lastSeqNumber = curSeqNum;

		} else if (this.lastSeqNumber - this.lastSeqNumber < -100) {
			// Sequence counter rolled over
			this.lastSeqNumber = curSeqNum;
			seqRollOverCount++;

		} else {
			// This was probably a duplicate or a late arrival.
		}

		// Calculate jitter
		if (this.lastRtpPkt > 0) {

			long D = (pkt.getTimeStamp() - curTime)
					- (this.lastRtpTimestamp - this.lastRtpPkt);
			if (D < 0)
				D = (-1) * D;

			this.interArrivalJitter += ((double) D - this.interArrivalJitter) / 16.0;
		}

		lastRtpPkt = curTime;
		lastRtpTimestamp = pkt.getTimeStamp();
	}

	/**
	 * Calculates the extended highest sequence received by adding the last
	 * sequence number to 65536 times the number of times the sequence counter
	 * has rolled over.
	 * 
	 * @return extended highest sequence
	 */
	protected long getExtHighSeqRecv() {
		return (65536 * seqRollOverCount + lastSeqNumber);
	}

	/**
	 * Get the fraction of lost packets, calculated as described in RFC 3550 as
	 * a fraction of 256.
	 * 
	 * @return the fraction of lost packets since last SR received
	 */
	protected int getFractionLost() {
		int expected = (lastSeqNumber - lastSRRseqNumber);
		if (expected < 0)
			expected = 65536 + expected;

		int fraction = 256 * (expected - receivedSinceLastSR);
		if (expected > 0) {
			fraction = (fraction / expected);
		} else {
			fraction = 0;
		}

		// Clear counters
		receivedSinceLastSR = 0;
		lastSRRseqNumber = lastSeqNumber;

		return fraction;
	}

	/**
	 * The total number of packets lost during the session.
	 * 
	 * Returns zero if loss is negative, i.e. duplicates have been received.
	 * 
	 * @return number of lost packets, or zero.
	 */
	protected long getLostPktCount() {
		long lost = (this.getExtHighSeqRecv() - this.firstSeqNumber)
				- receivedPkts;

		if (lost < 0)
			lost = 0;
		return lost;
	}

	/**
	 * 
	 * @return the interArrivalJitter, calculated continuously
	 */
	protected double getInterArrivalJitter() {
		return this.interArrivalJitter;
	}

	/**
	 * Set the timestamp for last sender report
	 * 
	 * @param ntp1
	 *            high order bits
	 * @param ntp2
	 *            low order bits
	 */
	protected void setTimeStampLSR(long ntp1, long ntp2) {
		// Use what we've got
		byte[] high = StaticProcs.uIntLongToByteWord(ntp1);
		byte[] low = StaticProcs.uIntLongToByteWord(ntp2);
		low[3] = low[1];
		low[2] = low[0];
		low[1] = high[3];
		low[0] = high[2];

		this.timeStampLSR = StaticProcs.bytesToUIntLong(low, 0);
	}

	/**
	 * Calculate the delay between the last received sender report and now.
	 * 
	 * @return the delay in units of 1/65.536ms
	 */
	protected long delaySinceLastSR() {
		if (this.timeReceivedLSR < 1)
			return 0;

		long delay = System.currentTimeMillis() - this.timeReceivedLSR;

		// Convert ms into 1/65536s = 1/65.536ms
		return (long) ((double) delay * 65.536);
	}

	/**
	 * Only for debugging purposes
	 */
	public void debugPrint() {
		System.out.print(" Participant.debugPrint() SSRC:" + this.ssrc
				+ " CNAME:" + this.cname);
		if (this.rtpAddress != null)
			System.out.print(" RTP:" + this.rtpAddress.toString());
		if (this.rtcpAddress != null)
			System.out.print(" RTCP:" + this.rtcpAddress.toString());
		System.out.println("");

		System.out.println("                          Packets received:"
				+ this.receivedPkts);
	}
}
