package eu.siacs.conversations.xmpp.jingle;

import android.os.SystemClock;
import android.util.Log;

import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.base.Strings;
import com.google.common.collect.Collections2;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;
import com.google.common.primitives.Ints;

import org.webrtc.EglBase;
import org.webrtc.IceCandidate;
import org.webrtc.PeerConnection;
import org.webrtc.VideoTrack;

import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;

import eu.siacs.conversations.Config;
import eu.siacs.conversations.entities.Conversation;
import eu.siacs.conversations.entities.Conversational;
import eu.siacs.conversations.entities.Message;
import eu.siacs.conversations.entities.RtpSessionStatus;
import eu.siacs.conversations.services.AppRTCAudioManager;
import eu.siacs.conversations.xml.Element;
import eu.siacs.conversations.xml.Namespace;
import eu.siacs.conversations.xmpp.jingle.stanzas.Group;
import eu.siacs.conversations.xmpp.jingle.stanzas.IceUdpTransportInfo;
import eu.siacs.conversations.xmpp.jingle.stanzas.JinglePacket;
import eu.siacs.conversations.xmpp.jingle.stanzas.Propose;
import eu.siacs.conversations.xmpp.jingle.stanzas.Reason;
import eu.siacs.conversations.xmpp.jingle.stanzas.RtpDescription;
import eu.siacs.conversations.xmpp.stanzas.IqPacket;
import eu.siacs.conversations.xmpp.stanzas.MessagePacket;
import rocks.xmpp.addr.Jid;

public class JingleRtpConnection extends AbstractJingleConnection implements WebRTCWrapper.EventCallback {

    public static final List<State> STATES_SHOWING_ONGOING_CALL = Arrays.asList(
            State.PROCEED,
            State.SESSION_INITIALIZED,
            State.SESSION_INITIALIZED_PRE_APPROVED,
            State.SESSION_ACCEPTED
    );

    private static final List<State> TERMINATED = Arrays.asList(
            State.TERMINATED_SUCCESS,
            State.TERMINATED_DECLINED_OR_BUSY,
            State.TERMINATED_CONNECTIVITY_ERROR,
            State.TERMINATED_CANCEL_OR_TIMEOUT,
            State.TERMINATED_APPLICATION_FAILURE
    );

    private static final Map<State, Collection<State>> VALID_TRANSITIONS;

    static {
        final ImmutableMap.Builder<State, Collection<State>> transitionBuilder = new ImmutableMap.Builder<>();
        transitionBuilder.put(State.NULL, ImmutableList.of(
                State.PROPOSED,
                State.SESSION_INITIALIZED,
                State.TERMINATED_APPLICATION_FAILURE
        ));
        transitionBuilder.put(State.PROPOSED, ImmutableList.of(
                State.ACCEPTED,
                State.PROCEED,
                State.REJECTED,
                State.RETRACTED,
                State.TERMINATED_APPLICATION_FAILURE,
                State.TERMINATED_CONNECTIVITY_ERROR //only used when the xmpp connection rebinds
        ));
        transitionBuilder.put(State.PROCEED, ImmutableList.of(
                State.SESSION_INITIALIZED_PRE_APPROVED,
                State.TERMINATED_SUCCESS,
                State.TERMINATED_APPLICATION_FAILURE,
                State.TERMINATED_CONNECTIVITY_ERROR //at this state used for error bounces of the proceed message
        ));
        transitionBuilder.put(State.SESSION_INITIALIZED, ImmutableList.of(
                State.SESSION_ACCEPTED,
                State.TERMINATED_SUCCESS,
                State.TERMINATED_DECLINED_OR_BUSY,
                State.TERMINATED_CONNECTIVITY_ERROR,  //at this state used for IQ errors and IQ timeouts
                State.TERMINATED_CANCEL_OR_TIMEOUT,
                State.TERMINATED_APPLICATION_FAILURE
        ));
        transitionBuilder.put(State.SESSION_INITIALIZED_PRE_APPROVED, ImmutableList.of(
                State.SESSION_ACCEPTED,
                State.TERMINATED_SUCCESS,
                State.TERMINATED_DECLINED_OR_BUSY,
                State.TERMINATED_CONNECTIVITY_ERROR,  //at this state used for IQ errors and IQ timeouts
                State.TERMINATED_CANCEL_OR_TIMEOUT,
                State.TERMINATED_APPLICATION_FAILURE
        ));
        transitionBuilder.put(State.SESSION_ACCEPTED, ImmutableList.of(
                State.TERMINATED_SUCCESS,
                State.TERMINATED_DECLINED_OR_BUSY,
                State.TERMINATED_CONNECTIVITY_ERROR,
                State.TERMINATED_CANCEL_OR_TIMEOUT,
                State.TERMINATED_APPLICATION_FAILURE
        ));
        VALID_TRANSITIONS = transitionBuilder.build();
    }

    private final WebRTCWrapper webRTCWrapper = new WebRTCWrapper(this);
    private final ArrayDeque<IceCandidate> pendingIceCandidates = new ArrayDeque<>();
    private final Message message;
    private State state = State.NULL;
    private Set<Media> proposedMedia;
    private RtpContentMap initiatorRtpContentMap;
    private RtpContentMap responderRtpContentMap;
    private long rtpConnectionStarted = 0; //time of 'connected'


    JingleRtpConnection(JingleConnectionManager jingleConnectionManager, Id id, Jid initiator) {
        super(jingleConnectionManager, id, initiator);
        final Conversation conversation = jingleConnectionManager.getXmppConnectionService().findOrCreateConversation(
                id.account,
                id.with.asBareJid(),
                false,
                false
        );
        this.message = new Message(
                conversation,
                isInitiator() ? Message.STATUS_SEND : Message.STATUS_RECEIVED,
                Message.TYPE_RTP_SESSION,
                id.sessionId
        );
    }

    private static State reasonToState(Reason reason) {
        switch (reason) {
            case SUCCESS:
                return State.TERMINATED_SUCCESS;
            case DECLINE:
            case BUSY:
                return State.TERMINATED_DECLINED_OR_BUSY;
            case CANCEL:
            case TIMEOUT:
                return State.TERMINATED_CANCEL_OR_TIMEOUT;
            case FAILED_APPLICATION:
            case SECURITY_ERROR:
            case UNSUPPORTED_TRANSPORTS:
            case UNSUPPORTED_APPLICATIONS:
                return State.TERMINATED_APPLICATION_FAILURE;
            default:
                return State.TERMINATED_CONNECTIVITY_ERROR;
        }
    }

    @Override
    synchronized void deliverPacket(final JinglePacket jinglePacket) {
        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": packet delivered to JingleRtpConnection");
        switch (jinglePacket.getAction()) {
            case SESSION_INITIATE:
                receiveSessionInitiate(jinglePacket);
                break;
            case TRANSPORT_INFO:
                receiveTransportInfo(jinglePacket);
                break;
            case SESSION_ACCEPT:
                receiveSessionAccept(jinglePacket);
                break;
            case SESSION_TERMINATE:
                receiveSessionTerminate(jinglePacket);
                break;
            default:
                respondOk(jinglePacket);
                Log.d(Config.LOGTAG, String.format("%s: received unhandled jingle action %s", id.account.getJid().asBareJid(), jinglePacket.getAction()));
                break;
        }
    }

    @Override
    synchronized void notifyRebound() {
        if (TERMINATED.contains(this.state)) {
            return;
        }
        webRTCWrapper.close();
        if (!isInitiator() && isInState(State.PROPOSED, State.SESSION_INITIALIZED)) {
            xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
        }
        if (isInState(State.SESSION_INITIALIZED, State.SESSION_INITIALIZED_PRE_APPROVED, State.SESSION_ACCEPTED)) {
            //we might have already changed resources (full jid) at this point; so this might not even reach the other party
            sendSessionTerminate(Reason.CONNECTIVITY_ERROR);
        } else {
            transitionOrThrow(State.TERMINATED_CONNECTIVITY_ERROR);
            jingleConnectionManager.finishConnection(this);
        }
    }

    private void receiveSessionTerminate(final JinglePacket jinglePacket) {
        respondOk(jinglePacket);
        final JinglePacket.ReasonWrapper wrapper = jinglePacket.getReason();
        final State previous = this.state;
        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": received session terminate reason=" + wrapper.reason + "(" + Strings.nullToEmpty(wrapper.text) + ") while in state " + previous);
        if (TERMINATED.contains(previous)) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": ignoring session terminate because already in " + previous);
            return;
        }
        webRTCWrapper.close();
        final State target = reasonToState(wrapper.reason);
        transitionOrThrow(target);
        writeLogMessage(target);
        if (previous == State.PROPOSED || previous == State.SESSION_INITIALIZED) {
            xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
        }
        jingleConnectionManager.finishConnection(this);
    }

    private void receiveTransportInfo(final JinglePacket jinglePacket) {
        if (isInState(State.SESSION_INITIALIZED, State.SESSION_INITIALIZED_PRE_APPROVED, State.SESSION_ACCEPTED)) {
            respondOk(jinglePacket);
            final RtpContentMap contentMap;
            try {
                contentMap = RtpContentMap.of(jinglePacket);
            } catch (IllegalArgumentException | NullPointerException e) {
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": improperly formatted contents; ignoring", e);
                return;
            }
            final RtpContentMap rtpContentMap = isInitiator() ? this.responderRtpContentMap : this.initiatorRtpContentMap;
            final Group originalGroup = rtpContentMap != null ? rtpContentMap.group : null;
            final List<String> identificationTags = originalGroup == null ? Collections.emptyList() : originalGroup.getIdentificationTags();
            if (identificationTags.size() == 0) {
                Log.w(Config.LOGTAG, id.account.getJid().asBareJid() + ": no identification tags found in initial offer. we won't be able to calculate mLineIndices");
            }
            for (final Map.Entry<String, RtpContentMap.DescriptionTransport> content : contentMap.contents.entrySet()) {
                final String ufrag = content.getValue().transport.getAttribute("ufrag");
                for (final IceUdpTransportInfo.Candidate candidate : content.getValue().transport.getCandidates()) {
                    final String sdp = candidate.toSdpAttribute(ufrag);
                    final String sdpMid = content.getKey();
                    final int mLineIndex = identificationTags.indexOf(sdpMid);
                    final IceCandidate iceCandidate = new IceCandidate(sdpMid, mLineIndex, sdp);
                    if (isInState(State.SESSION_ACCEPTED)) {
                        Log.d(Config.LOGTAG, "received candidate: " + iceCandidate);
                        this.webRTCWrapper.addIceCandidate(iceCandidate);
                    } else {
                        this.pendingIceCandidates.offer(iceCandidate);
                        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": put ICE candidate on backlog");
                    }
                }
            }
        } else {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": received transport info while in state=" + this.state);
            terminateWithOutOfOrder(jinglePacket);
        }
    }

    private void receiveSessionInitiate(final JinglePacket jinglePacket) {
        if (isInitiator()) {
            Log.d(Config.LOGTAG, String.format("%s: received session-initiate even though we were initiating", id.account.getJid().asBareJid()));
            terminateWithOutOfOrder(jinglePacket);
            return;
        }
        final RtpContentMap contentMap;
        try {
            contentMap = RtpContentMap.of(jinglePacket);
            contentMap.requireContentDescriptions();
            contentMap.requireDTLSFingerprint();
        } catch (final IllegalArgumentException | IllegalStateException | NullPointerException e) {
            respondOk(jinglePacket);
            sendSessionTerminate(Reason.FAILED_APPLICATION, e.getMessage());
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": improperly formatted contents", e);
            return;
        }
        Log.d(Config.LOGTAG, "processing session-init with " + contentMap.contents.size() + " contents");
        final State target;
        if (this.state == State.PROCEED) {
            Preconditions.checkState(
                    proposedMedia != null && proposedMedia.size() > 0,
                    "proposed media must be set when processing pre-approved session-initiate"
            );
            if (!this.proposedMedia.equals(contentMap.getMedia())) {
                sendSessionTerminate(Reason.SECURITY_ERROR, String.format(
                        "Your session proposal (Jingle Message Initiation) included media %s but your session-initiate was %s",
                        this.proposedMedia,
                        contentMap.getMedia()
                ));
                return;
            }
            target = State.SESSION_INITIALIZED_PRE_APPROVED;
        } else {
            target = State.SESSION_INITIALIZED;
        }
        if (transition(target)) {
            respondOk(jinglePacket);
            this.initiatorRtpContentMap = contentMap;
            if (target == State.SESSION_INITIALIZED_PRE_APPROVED) {
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": automatically accepting session-initiate");
                sendSessionAccept();
            } else {
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": received not pre-approved session-initiate. start ringing");
                startRinging();
            }
        } else {
            Log.d(Config.LOGTAG, String.format("%s: received session-initiate while in state %s", id.account.getJid().asBareJid(), state));
            terminateWithOutOfOrder(jinglePacket);
        }
    }

    private void receiveSessionAccept(final JinglePacket jinglePacket) {
        if (!isInitiator()) {
            Log.d(Config.LOGTAG, String.format("%s: received session-accept even though we were responding", id.account.getJid().asBareJid()));
            terminateWithOutOfOrder(jinglePacket);
            return;
        }
        final RtpContentMap contentMap;
        try {
            contentMap = RtpContentMap.of(jinglePacket);
            contentMap.requireContentDescriptions();
            contentMap.requireDTLSFingerprint();
        } catch (IllegalArgumentException | IllegalStateException | NullPointerException e) {
            respondOk(jinglePacket);
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": improperly formatted contents in session-accept", e);
            webRTCWrapper.close();
            sendSessionTerminate(Reason.FAILED_APPLICATION, e.getMessage());
            return;
        }
        Log.d(Config.LOGTAG, "processing session-accept with " + contentMap.contents.size() + " contents");
        if (transition(State.SESSION_ACCEPTED)) {
            respondOk(jinglePacket);
            receiveSessionAccept(contentMap);
        } else {
            Log.d(Config.LOGTAG, String.format("%s: received session-accept while in state %s", id.account.getJid().asBareJid(), state));
            respondOk(jinglePacket);
        }
    }

    private void receiveSessionAccept(final RtpContentMap contentMap) {
        this.responderRtpContentMap = contentMap;
        final SessionDescription sessionDescription;
        try {
            sessionDescription = SessionDescription.of(contentMap);
        } catch (final IllegalArgumentException | NullPointerException e) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": unable convert offer from session-accept to SDP", e);
            webRTCWrapper.close();
            sendSessionTerminate(Reason.FAILED_APPLICATION, e.getMessage());
            return;
        }
        org.webrtc.SessionDescription answer = new org.webrtc.SessionDescription(
                org.webrtc.SessionDescription.Type.ANSWER,
                sessionDescription.toString()
        );
        try {
            this.webRTCWrapper.setRemoteDescription(answer).get();
        } catch (Exception e) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": unable to set remote description after receiving session-accept", e);
            webRTCWrapper.close();
            sendSessionTerminate(Reason.FAILED_APPLICATION);
        }
    }

    private void sendSessionAccept() {
        final RtpContentMap rtpContentMap = this.initiatorRtpContentMap;
        if (rtpContentMap == null) {
            throw new IllegalStateException("initiator RTP Content Map has not been set");
        }
        final SessionDescription offer;
        try {
            offer = SessionDescription.of(rtpContentMap);
        } catch (final IllegalArgumentException | NullPointerException e) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": unable convert offer from session-initiate to SDP", e);
            webRTCWrapper.close();
            sendSessionTerminate(Reason.FAILED_APPLICATION, e.getMessage());
            return;
        }
        sendSessionAccept(rtpContentMap.getMedia(), offer);
    }

    private void sendSessionAccept(final Set<Media> media, final SessionDescription offer) {
        discoverIceServers(iceServers -> sendSessionAccept(media, offer, iceServers));
    }

    private synchronized void sendSessionAccept(final Set<Media> media, final SessionDescription offer, final List<PeerConnection.IceServer> iceServers) {
        if (TERMINATED.contains(this.state)) {
            Log.w(Config.LOGTAG, id.account.getJid().asBareJid() + ": ICE servers got discovered when session was already terminated. nothing to do.");
            return;
        }
        try {
            setupWebRTC(media, iceServers);
        } catch (WebRTCWrapper.InitializationException e) {
            sendSessionTerminate(Reason.FAILED_APPLICATION);
            return;
        }
        final org.webrtc.SessionDescription sdp = new org.webrtc.SessionDescription(
                org.webrtc.SessionDescription.Type.OFFER,
                offer.toString()
        );
        try {
            this.webRTCWrapper.setRemoteDescription(sdp).get();
            addIceCandidatesFromBlackLog();
            org.webrtc.SessionDescription webRTCSessionDescription = this.webRTCWrapper.createAnswer().get();
            final SessionDescription sessionDescription = SessionDescription.parse(webRTCSessionDescription.description);
            final RtpContentMap respondingRtpContentMap = RtpContentMap.of(sessionDescription);
            sendSessionAccept(respondingRtpContentMap);
            this.webRTCWrapper.setLocalDescription(webRTCSessionDescription);
        } catch (Exception e) {
            Log.d(Config.LOGTAG, "unable to send session accept", e);

        }
    }

    private void addIceCandidatesFromBlackLog() {
        while (!this.pendingIceCandidates.isEmpty()) {
            final IceCandidate iceCandidate = this.pendingIceCandidates.poll();
            this.webRTCWrapper.addIceCandidate(iceCandidate);
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": added ICE candidate from back log " + iceCandidate);
        }
    }

    private void sendSessionAccept(final RtpContentMap rtpContentMap) {
        this.responderRtpContentMap = rtpContentMap;
        this.transitionOrThrow(State.SESSION_ACCEPTED);
        final JinglePacket sessionAccept = rtpContentMap.toJinglePacket(JinglePacket.Action.SESSION_ACCEPT, id.sessionId);
        Log.d(Config.LOGTAG, sessionAccept.toString());
        send(sessionAccept);
    }

    synchronized void deliveryMessage(final Jid from, final Element message, final String serverMessageId, final long timestamp) {
        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": delivered message to JingleRtpConnection " + message);
        switch (message.getName()) {
            case "propose":
                receivePropose(from, Propose.upgrade(message), serverMessageId, timestamp);
                break;
            case "proceed":
                receiveProceed(from, serverMessageId, timestamp);
                break;
            case "retract":
                receiveRetract(from, serverMessageId, timestamp);
                break;
            case "reject":
                receiveReject(from, serverMessageId, timestamp);
                break;
            case "accept":
                receiveAccept(from, serverMessageId, timestamp);
                break;
            default:
                break;
        }
    }

    void deliverFailedProceed() {
        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": receive message error for proceed message");
        if (transition(State.TERMINATED_CONNECTIVITY_ERROR)) {
            webRTCWrapper.close();
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": transitioned into connectivity error");
            this.jingleConnectionManager.finishConnection(this);
        }
    }

    private void receiveAccept(final Jid from, final String serverMsgId, final long timestamp) {
        final boolean originatedFromMyself = from.asBareJid().equals(id.account.getJid().asBareJid());
        if (originatedFromMyself) {
            if (transition(State.ACCEPTED)) {
                if (serverMsgId != null) {
                    this.message.setServerMsgId(serverMsgId);
                }
                this.message.setTime(timestamp);
                this.message.setCarbon(true); //indicate that call was accepted on other device
                this.writeLogMessageSuccess(0);
                this.xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
                this.jingleConnectionManager.finishConnection(this);
            } else {
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": unable to transition to accept because already in state=" + this.state);
            }
        } else {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": ignoring 'accept' from " + from);
        }
    }

    private void receiveReject(Jid from, String serverMsgId, long timestamp) {
        final boolean originatedFromMyself = from.asBareJid().equals(id.account.getJid().asBareJid());
        //reject from another one of my clients
        if (originatedFromMyself) {
            if (transition(State.REJECTED)) {
                this.xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
                this.jingleConnectionManager.finishConnection(this);
                if (serverMsgId != null) {
                    this.message.setServerMsgId(serverMsgId);
                }
                this.message.setTime(timestamp);
                this.message.setCarbon(true); //indicate that call was rejected on other device
                writeLogMessageMissed();
            } else {
                Log.d(Config.LOGTAG, "not able to transition into REJECTED because already in " + this.state);
            }
        } else {
            Log.d(Config.LOGTAG, id.account.getJid() + ": ignoring reject from " + from + " for session with " + id.with);
        }
    }

    private void receivePropose(final Jid from, final Propose propose, final String serverMsgId, final long timestamp) {
        final boolean originatedFromMyself = from.asBareJid().equals(id.account.getJid().asBareJid());
        if (originatedFromMyself) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": saw proposal from mysql. ignoring");
        } else if (isInState(State.NULL)) {
            final Collection<RtpDescription> descriptions = Collections2.transform(
                    Collections2.filter(propose.getDescriptions(), d -> d instanceof RtpDescription),
                    input -> (RtpDescription) input
            );
            final Collection<Media> media = Collections2.transform(descriptions, RtpDescription::getMedia);
            Preconditions.checkState(!media.contains(Media.UNKNOWN), "RTP descriptions contain unknown media");
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": received session proposal from " + from + " for " + media);
            this.proposedMedia = Sets.newHashSet(media);
            transitionOrThrow(State.PROPOSED);
            if (serverMsgId != null) {
                this.message.setServerMsgId(serverMsgId);
            }
            this.message.setTime(timestamp);
            startRinging();
        } else {
            Log.d(Config.LOGTAG, id.account.getJid() + ": ignoring session proposal because already in " + state);
        }
    }

    private void startRinging() {
        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": received call from " + id.with + ". start ringing");
        xmppConnectionService.getNotificationService().showIncomingCallNotification(id, getMedia());
    }

    private void receiveProceed(final Jid from, final String serverMsgId, final long timestamp) {
        final Set<Media> media = Preconditions.checkNotNull(this.proposedMedia, "Proposed media has to be set before handling proceed");
        Preconditions.checkState(media.size() > 0, "Proposed media should not be empty");
        if (from.equals(id.with)) {
            if (isInitiator()) {
                if (transition(State.PROCEED)) {
                    if (serverMsgId != null) {
                        this.message.setServerMsgId(serverMsgId);
                    }
                    this.message.setTime(timestamp);
                    this.sendSessionInitiate(media, State.SESSION_INITIALIZED_PRE_APPROVED);
                } else {
                    Log.d(Config.LOGTAG, String.format("%s: ignoring proceed because already in %s", id.account.getJid().asBareJid(), this.state));
                }
            } else {
                Log.d(Config.LOGTAG, String.format("%s: ignoring proceed because we were not initializing", id.account.getJid().asBareJid()));
            }
        } else if (from.asBareJid().equals(id.account.getJid().asBareJid())) {
            if (transition(State.ACCEPTED)) {
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": moved session with " + id.with + " into state accepted after received carbon copied procced");
                this.xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
                this.jingleConnectionManager.finishConnection(this);
            }
        } else {
            Log.d(Config.LOGTAG, String.format("%s: ignoring proceed from %s. was expected from %s", id.account.getJid().asBareJid(), from, id.with));
        }
    }

    private void receiveRetract(final Jid from, final String serverMsgId, final long timestamp) {
        if (from.equals(id.with)) {
            if (transition(State.RETRACTED)) {
                xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": session with " + id.with + " has been retracted (serverMsgId=" + serverMsgId + ")");
                if (serverMsgId != null) {
                    this.message.setServerMsgId(serverMsgId);
                }
                this.message.setTime(timestamp);
                writeLogMessageMissed();
                jingleConnectionManager.finishConnection(this);
            } else {
                Log.d(Config.LOGTAG, "ignoring retract because already in " + this.state);
            }
        } else {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": received retract from " + from + ". expected retract from" + id.with + ". ignoring");
        }
    }

    private void sendSessionInitiate(final Set<Media> media, final State targetState) {
        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": prepare session-initiate");
        discoverIceServers(iceServers -> sendSessionInitiate(media, targetState, iceServers));
    }

    private synchronized void sendSessionInitiate(final Set<Media> media, final State targetState, final List<PeerConnection.IceServer> iceServers) {
        if (TERMINATED.contains(this.state)) {
            Log.w(Config.LOGTAG, id.account.getJid().asBareJid() + ": ICE servers got discovered when session was already terminated. nothing to do.");
            return;
        }
        try {
            setupWebRTC(media, iceServers);
        } catch (WebRTCWrapper.InitializationException e) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": unable to initialize webrtc");
            transitionOrThrow(State.TERMINATED_APPLICATION_FAILURE);
            return;
        }
        try {
            org.webrtc.SessionDescription webRTCSessionDescription = this.webRTCWrapper.createOffer().get();
            final SessionDescription sessionDescription = SessionDescription.parse(webRTCSessionDescription.description);
            Log.d(Config.LOGTAG, "description: " + webRTCSessionDescription.description);
            final RtpContentMap rtpContentMap = RtpContentMap.of(sessionDescription);
            sendSessionInitiate(rtpContentMap, targetState);
            this.webRTCWrapper.setLocalDescription(webRTCSessionDescription).get();
        } catch (final Exception e) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": unable to sendSessionInitiate", e);
            webRTCWrapper.close();
            if (isInState(targetState)) {
                sendSessionTerminate(Reason.FAILED_APPLICATION);
            } else {
                transitionOrThrow(State.TERMINATED_APPLICATION_FAILURE);
            }
        }
    }

    private void sendSessionInitiate(RtpContentMap rtpContentMap, final State targetState) {
        this.initiatorRtpContentMap = rtpContentMap;
        this.transitionOrThrow(targetState);
        final JinglePacket sessionInitiate = rtpContentMap.toJinglePacket(JinglePacket.Action.SESSION_INITIATE, id.sessionId);
        send(sessionInitiate);
    }

    private void sendSessionTerminate(final Reason reason) {
        sendSessionTerminate(reason, null);
    }

    private void sendSessionTerminate(final Reason reason, final String text) {
        final State target = reasonToState(reason);
        transitionOrThrow(target);
        writeLogMessage(target);
        final JinglePacket jinglePacket = new JinglePacket(JinglePacket.Action.SESSION_TERMINATE, id.sessionId);
        jinglePacket.setReason(reason, text);
        Log.d(Config.LOGTAG, jinglePacket.toString());
        send(jinglePacket);
        jingleConnectionManager.finishConnection(this);
    }

    private void sendTransportInfo(final String contentName, IceUdpTransportInfo.Candidate candidate) {
        final RtpContentMap transportInfo;
        try {
            final RtpContentMap rtpContentMap = isInitiator() ? this.initiatorRtpContentMap : this.responderRtpContentMap;
            transportInfo = rtpContentMap.transportInfo(contentName, candidate);
        } catch (Exception e) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": unable to prepare transport-info from candidate for content=" + contentName);
            return;
        }
        final JinglePacket jinglePacket = transportInfo.toJinglePacket(JinglePacket.Action.TRANSPORT_INFO, id.sessionId);
        send(jinglePacket);
    }

    private void send(final JinglePacket jinglePacket) {
        jinglePacket.setTo(id.with);
        xmppConnectionService.sendIqPacket(id.account, jinglePacket, (account, response) -> {
            if (response.getType() == IqPacket.TYPE.ERROR) {
                final String errorCondition = response.getErrorCondition();
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": received IQ-error from " + response.getFrom() + " in RTP session. " + errorCondition);
                this.webRTCWrapper.close();
                final State target;
                if (Arrays.asList(
                        "service-unavailable",
                        "recipient-unavailable",
                        "remote-server-not-found",
                        "remote-server-timeout"
                ).contains(errorCondition)) {
                    target = State.TERMINATED_CONNECTIVITY_ERROR;
                } else {
                    target = State.TERMINATED_APPLICATION_FAILURE;
                }
                if (transition(target)) {
                    Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": terminated session with " + id.with);
                } else {
                    Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": not transitioning because already at state=" + this.state);
                }

            } else if (response.getType() == IqPacket.TYPE.TIMEOUT) {
                this.webRTCWrapper.close();
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": received IQ timeout in RTP session with " + id.with + ". terminating with connectivity error");
                transition(State.TERMINATED_CONNECTIVITY_ERROR);
                this.jingleConnectionManager.finishConnection(this);
            }
        });
    }

    private void terminateWithOutOfOrder(final JinglePacket jinglePacket) {
        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": terminating session with out-of-order");
        webRTCWrapper.close();
        transitionOrThrow(State.TERMINATED_APPLICATION_FAILURE);
        respondWithOutOfOrder(jinglePacket);
        jingleConnectionManager.finishConnection(this);
    }

    private void respondWithOutOfOrder(final JinglePacket jinglePacket) {
        jingleConnectionManager.respondWithJingleError(id.account, jinglePacket, "out-of-order", "unexpected-request", "wait");
    }

    private void respondOk(final JinglePacket jinglePacket) {
        xmppConnectionService.sendIqPacket(id.account, jinglePacket.generateResponse(IqPacket.TYPE.RESULT), null);
    }

    public RtpEndUserState getEndUserState() {
        switch (this.state) {
            case PROPOSED:
            case SESSION_INITIALIZED:
                if (isInitiator()) {
                    return RtpEndUserState.RINGING;
                } else {
                    return RtpEndUserState.INCOMING_CALL;
                }
            case PROCEED:
                if (isInitiator()) {
                    return RtpEndUserState.RINGING;
                } else {
                    return RtpEndUserState.ACCEPTING_CALL;
                }
            case SESSION_INITIALIZED_PRE_APPROVED:
                if (isInitiator()) {
                    return RtpEndUserState.RINGING;
                } else {
                    return RtpEndUserState.CONNECTING;
                }
            case SESSION_ACCEPTED:
                final PeerConnection.PeerConnectionState state = webRTCWrapper.getState();
                if (state == PeerConnection.PeerConnectionState.CONNECTED) {
                    return RtpEndUserState.CONNECTED;
                } else if (state == PeerConnection.PeerConnectionState.NEW || state == PeerConnection.PeerConnectionState.CONNECTING) {
                    return RtpEndUserState.CONNECTING;
                } else if (state == PeerConnection.PeerConnectionState.CLOSED) {
                    return RtpEndUserState.ENDING_CALL;
                } else if (state == PeerConnection.PeerConnectionState.FAILED) {
                    return RtpEndUserState.CONNECTIVITY_ERROR;
                } else {
                    return RtpEndUserState.ENDING_CALL;
                }
            case REJECTED:
            case TERMINATED_DECLINED_OR_BUSY:
                if (isInitiator()) {
                    return RtpEndUserState.DECLINED_OR_BUSY;
                } else {
                    return RtpEndUserState.ENDED;
                }
            case TERMINATED_SUCCESS:
            case ACCEPTED:
            case RETRACTED:
            case TERMINATED_CANCEL_OR_TIMEOUT:
                return RtpEndUserState.ENDED;
            case TERMINATED_CONNECTIVITY_ERROR:
                return RtpEndUserState.CONNECTIVITY_ERROR;
            case TERMINATED_APPLICATION_FAILURE:
                return RtpEndUserState.APPLICATION_ERROR;
        }
        throw new IllegalStateException(String.format("%s has no equivalent EndUserState", this.state));
    }

    public Set<Media> getMedia() {
        if (isInState(State.NULL)) {
            throw new IllegalStateException("RTP connection has not been initialized yet");
        }
        if (isInState(State.PROPOSED, State.PROCEED)) {
            return Preconditions.checkNotNull(this.proposedMedia, "RTP connection has not been  initialized properly");
        }
        return Preconditions.checkNotNull(initiatorRtpContentMap.getMedia());
    }


    public synchronized void acceptCall() {
        switch (this.state) {
            case PROPOSED:
                acceptCallFromProposed();
                break;
            case SESSION_INITIALIZED:
                acceptCallFromSessionInitialized();
                break;
            default:
                throw new IllegalStateException("Can not accept call from " + this.state);
        }
    }

    public synchronized void rejectCall() {
        switch (this.state) {
            case PROPOSED:
                rejectCallFromProposed();
                break;
            case SESSION_INITIALIZED:
                rejectCallFromSessionInitiate();
                break;
            default:
                throw new IllegalStateException("Can not reject call from " + this.state);
        }
    }

    public synchronized void endCall() {
        if (TERMINATED.contains(this.state)) {
            Log.w(Config.LOGTAG, id.account.getJid().asBareJid() + ": received endCall() when session has already been terminated. nothing to do");
            return;
        }
        if (isInState(State.PROPOSED) && !isInitiator()) {
            rejectCallFromProposed();
            return;
        }
        if (isInState(State.PROCEED)) {
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": ending call while in state PROCEED just means ending the connection");
            webRTCWrapper.close();
            jingleConnectionManager.finishConnection(this);
            transitionOrThrow(State.TERMINATED_SUCCESS); //arguably this wasn't success; but not a real failure either
            return;
        }
        if (isInitiator() && isInState(State.SESSION_INITIALIZED, State.SESSION_INITIALIZED_PRE_APPROVED)) {
            webRTCWrapper.close();
            sendSessionTerminate(Reason.CANCEL);
            return;
        }
        if (isInState(State.SESSION_INITIALIZED)) {
            rejectCallFromSessionInitiate();
            return;
        }
        if (isInState(State.SESSION_INITIALIZED_PRE_APPROVED, State.SESSION_ACCEPTED)) {
            webRTCWrapper.close();
            sendSessionTerminate(Reason.SUCCESS);
            return;
        }
        if (isInState(State.TERMINATED_APPLICATION_FAILURE, State.TERMINATED_CONNECTIVITY_ERROR, State.TERMINATED_DECLINED_OR_BUSY)) {
            Log.d(Config.LOGTAG, "ignoring request to end call because already in state " + this.state);
            return;
        }
        throw new IllegalStateException("called 'endCall' while in state " + this.state + ". isInitiator=" + isInitiator());
    }

    private void setupWebRTC(final Set<Media> media, final List<PeerConnection.IceServer> iceServers) throws WebRTCWrapper.InitializationException {
        final AppRTCAudioManager.SpeakerPhonePreference speakerPhonePreference;
        if (media.contains(Media.VIDEO)) {
            speakerPhonePreference = AppRTCAudioManager.SpeakerPhonePreference.SPEAKER;
        } else {
            speakerPhonePreference = AppRTCAudioManager.SpeakerPhonePreference.EARPIECE;
        }
        this.webRTCWrapper.setup(this.xmppConnectionService, speakerPhonePreference);
        this.webRTCWrapper.initializePeerConnection(media, iceServers);
    }

    private void acceptCallFromProposed() {
        transitionOrThrow(State.PROCEED);
        xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
        this.sendJingleMessage("accept", id.account.getJid().asBareJid());
        this.sendJingleMessage("proceed");
    }

    private void rejectCallFromProposed() {
        transitionOrThrow(State.REJECTED);
        writeLogMessageMissed();
        xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
        this.sendJingleMessage("reject");
        jingleConnectionManager.finishConnection(this);
    }

    private void rejectCallFromSessionInitiate() {
        webRTCWrapper.close();
        sendSessionTerminate(Reason.DECLINE);
        xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
    }

    private void sendJingleMessage(final String action) {
        sendJingleMessage(action, id.with);
    }

    private void sendJingleMessage(final String action, final Jid to) {
        final MessagePacket messagePacket = new MessagePacket();
        if ("proceed".equals(action)) {
            messagePacket.setId(JINGLE_MESSAGE_PROCEED_ID_PREFIX + id.sessionId);
        }
        messagePacket.setType(MessagePacket.TYPE_CHAT); //we want to carbon copy those
        messagePacket.setTo(to);
        messagePacket.addChild(action, Namespace.JINGLE_MESSAGE).setAttribute("id", id.sessionId);
        messagePacket.addChild("store", "urn:xmpp:hints");
        xmppConnectionService.sendMessagePacket(id.account, messagePacket);
    }

    private void acceptCallFromSessionInitialized() {
        xmppConnectionService.getNotificationService().cancelIncomingCallNotification();
        sendSessionAccept();
    }

    private synchronized boolean isInState(State... state) {
        return Arrays.asList(state).contains(this.state);
    }

    private synchronized boolean transition(final State target) {
        final Collection<State> validTransitions = VALID_TRANSITIONS.get(this.state);
        if (validTransitions != null && validTransitions.contains(target)) {
            this.state = target;
            Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": transitioned into " + target);
            updateEndUserState();
            updateOngoingCallNotification();
            return true;
        } else {
            return false;
        }
    }

    public void transitionOrThrow(final State target) {
        if (!transition(target)) {
            throw new IllegalStateException(String.format("Unable to transition from %s to %s", this.state, target));
        }
    }

    @Override
    public void onIceCandidate(final IceCandidate iceCandidate) {
        final IceUdpTransportInfo.Candidate candidate = IceUdpTransportInfo.Candidate.fromSdpAttribute(iceCandidate.sdp);
        Log.d(Config.LOGTAG, "sending candidate: " + iceCandidate.toString());
        sendTransportInfo(iceCandidate.sdpMid, candidate);
    }

    @Override
    public void onConnectionChange(final PeerConnection.PeerConnectionState newState) {
        Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": PeerConnectionState changed to " + newState);
        updateEndUserState();
        if (newState == PeerConnection.PeerConnectionState.CONNECTED && this.rtpConnectionStarted == 0) {
            this.rtpConnectionStarted = SystemClock.elapsedRealtime();
        }
        if (newState == PeerConnection.PeerConnectionState.FAILED) {
            if (TERMINATED.contains(this.state)) {
                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": not sending session-terminate after connectivity error because session is already in state " + this.state);
                return;
            }
            sendSessionTerminate(Reason.CONNECTIVITY_ERROR);
        }
    }

    public AppRTCAudioManager getAudioManager() {
        return webRTCWrapper.getAudioManager();
    }

    public boolean isMicrophoneEnabled() {
        return webRTCWrapper.isMicrophoneEnabled();
    }

    public void setMicrophoneEnabled(final boolean enabled) {
        webRTCWrapper.setMicrophoneEnabled(enabled);
    }

    @Override
    public void onAudioDeviceChanged(AppRTCAudioManager.AudioDevice selectedAudioDevice, Set<AppRTCAudioManager.AudioDevice> availableAudioDevices) {
        xmppConnectionService.notifyJingleRtpConnectionUpdate(selectedAudioDevice, availableAudioDevices);
    }

    private void updateEndUserState() {
        xmppConnectionService.notifyJingleRtpConnectionUpdate(id.account, id.with, id.sessionId, getEndUserState());
    }

    private void updateOngoingCallNotification() {
        if (STATES_SHOWING_ONGOING_CALL.contains(this.state)) {
            xmppConnectionService.setOngoingCall(id);
        } else {
            xmppConnectionService.removeOngoingCall(id);
        }
    }

    private void discoverIceServers(final OnIceServersDiscovered onIceServersDiscovered) {
        if (id.account.getXmppConnection().getFeatures().extendedServiceDiscovery()) {
            final IqPacket request = new IqPacket(IqPacket.TYPE.GET);
            request.setTo(Jid.of(id.account.getJid().getDomain()));
            request.addChild("services", Namespace.EXTERNAL_SERVICE_DISCOVERY);
            xmppConnectionService.sendIqPacket(id.account, request, (account, response) -> {
                ImmutableList.Builder<PeerConnection.IceServer> listBuilder = new ImmutableList.Builder<>();
                if (response.getType() == IqPacket.TYPE.RESULT) {
                    final Element services = response.findChild("services", Namespace.EXTERNAL_SERVICE_DISCOVERY);
                    final List<Element> children = services == null ? Collections.emptyList() : services.getChildren();
                    for (final Element child : children) {
                        if ("service".equals(child.getName())) {
                            final String type = child.getAttribute("type");
                            final String host = child.getAttribute("host");
                            final String sport = child.getAttribute("port");
                            final Integer port = sport == null ? null : Ints.tryParse(sport);
                            final String transport = child.getAttribute("transport");
                            final String username = child.getAttribute("username");
                            final String password = child.getAttribute("password");
                            if (Strings.isNullOrEmpty(host) || port == null) {
                                continue;
                            }
                            if (port < 0 || port > 65535) {
                                continue;
                            }
                            if (Arrays.asList("stun", "turn").contains(type) || Arrays.asList("udp", "tcp").contains(transport)) {
                                //TODO wrap ipv6 addresses
                                PeerConnection.IceServer.Builder iceServerBuilder = PeerConnection.IceServer.builder(String.format("%s:%s:%s?transport=%s", type, host, port, transport));
                                if (username != null && password != null) {
                                    iceServerBuilder.setUsername(username);
                                    iceServerBuilder.setPassword(password);
                                } else if (Arrays.asList("turn", "turns").contains(type)) {
                                    //The WebRTC spec requires throwing an InvalidAccessError when username (from libwebrtc source coder)
                                    //https://chromium.googlesource.com/external/webrtc/+/master/pc/ice_server_parsing.cc
                                    Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": skipping " + type + "/" + transport + " without username and password");
                                    continue;
                                }
                                final PeerConnection.IceServer iceServer = iceServerBuilder.createIceServer();
                                Log.d(Config.LOGTAG, id.account.getJid().asBareJid() + ": discovered ICE Server: " + iceServer);
                                listBuilder.add(iceServer);
                            }
                        }
                    }
                }
                List<PeerConnection.IceServer> iceServers = listBuilder.build();
                if (iceServers.size() == 0) {
                    Log.w(Config.LOGTAG, id.account.getJid().asBareJid() + ": no ICE server found " + response);
                }
                onIceServersDiscovered.onIceServersDiscovered(iceServers);
            });
        } else {
            Log.w(Config.LOGTAG, id.account.getJid().asBareJid() + ": has no external service discovery");
            onIceServersDiscovered.onIceServersDiscovered(Collections.emptyList());
        }
    }

    private void writeLogMessage(final State state) {
        final long started = this.rtpConnectionStarted;
        long duration = started <= 0 ? 0 : SystemClock.elapsedRealtime() - started;
        if (state == State.TERMINATED_SUCCESS || (state == State.TERMINATED_CONNECTIVITY_ERROR && duration > 0)) {
            writeLogMessageSuccess(duration);
        } else {
            writeLogMessageMissed();
        }
    }

    private void writeLogMessageSuccess(final long duration) {
        this.message.setBody(new RtpSessionStatus(true, duration).toString());
        this.writeMessage();
    }

    private void writeLogMessageMissed() {
        this.message.setBody(new RtpSessionStatus(false, 0).toString());
        this.writeMessage();
    }

    private void writeMessage() {
        final Conversational conversational = message.getConversation();
        if (conversational instanceof Conversation) {
            ((Conversation) conversational).add(this.message);
            xmppConnectionService.databaseBackend.createMessage(message);
            xmppConnectionService.updateConversationUi();
        } else {
            throw new IllegalStateException("Somehow the conversation in a message was a stub");
        }
    }

    public State getState() {
        return this.state;
    }

    public Optional<VideoTrack> geLocalVideoTrack() {
        return webRTCWrapper.getLocalVideoTrack();
    }

    public Optional<VideoTrack> getRemoteVideoTrack() {
        return webRTCWrapper.getRemoteVideoTrack();
    }


    public EglBase.Context getEglBaseContext() {
        return webRTCWrapper.getEglBaseContext();
    }

    public void setProposedMedia(final Set<Media> media) {
        this.proposedMedia = media;
    }

    private interface OnIceServersDiscovered {
        void onIceServersDiscovered(List<PeerConnection.IceServer> iceServers);
    }
}