// The session model contains information about the music
// sessions that the current client has joined.
(function(context,$) {

    "use strict";

    context.JK = context.JK || {};
    var logger = context.JK.logger;

    context.JK.SessionModel = function(app, server, client) {
        var clientId = client.clientID;
        var currentSessionId = null; // Set on join, prior to setting currentSession.
        var currentSession = null;
        var currentOrLastSession = null;
        var subscribers = {};
        var users = {}; // User info for session participants
        var rest = context.JK.Rest();
        var requestingSessionRefresh = false;
        var pendingSessionRefresh = false;
        var recordingModel = new context.JK.RecordingModel(app, this, rest, context.jamClient);
        var currentTrackChanges = 0;
        // we track all the clientIDs of all the participants ever seen by this session, so that we can reliably convert a clientId from the backend into a username/avatar
        var participantsEverSeen = {};

      function id() {
            return currentSession ? currentSession.id : null;
        }

        function participants() {
            if (currentSession) {
                return currentSession.participants;
            } else {
                return [];
            }
        }

        function isPlayingRecording() {
            // this is the server's state; there is no guarantee that the local tracks
            // requested from the backend will have corresponding track information
            return currentSession && currentSession.claimed_recording;
        }

        function recordedTracks() {
            if(currentSession && currentSession.claimed_recording) {
                return currentSession.claimed_recording.recording.recorded_tracks
            }
            else {
                return null;
            }
        }

        function creatorId() {
            if(!currentSession) {
                throw "creator is not known"
            }
            return currentSession.user_id;
        }

        function alreadyInSession() {
            var inSession = false;
            $.each(participants(), function(index, participant) {
                 if(participant.user.id == context.JK.currentUserId) {
                     inSession = true;
                     return false;
                 }
            });
            return inSession;
        }

        /**
        * Join the session specified by the provided id.
        */
        function joinSession(sessionId) {
            currentSessionId = sessionId;
            logger.debug("SessionModel.joinSession(" + sessionId + ")");
            var deferred = joinSessionRest(sessionId);

            deferred
                .done(function(){
                    logger.debug("calling jamClient.JoinSession");
                    if(!alreadyInSession()) {
                        // on temporary disconnect scenarios, a user may already be in a session when they enter this path
                        // so we avoid double counting
                        context.JK.GA.trackSessionMusicians(context.JK.GA.SessionCreationTypes.join);
                    }

                    recordingModel.reset();
                    client.JoinSession({ sessionID: sessionId });
                    refreshCurrentSession();
                    server.registerMessageCallback(context.JK.MessageType.SESSION_JOIN, trackChanges);
                    server.registerMessageCallback(context.JK.MessageType.SESSION_DEPART, trackChanges);
                    server.registerMessageCallback(context.JK.MessageType.TRACKS_CHANGED, trackChanges);
                })
                .fail(function() {
                    currentSessionId = null;
                });

            return deferred;
        }

        function performLeaveSession(deferred) {

            logger.debug("SessionModel.leaveCurrentSession()");
            // TODO - sessionChanged will be called with currentSession = null\
            server.unregisterMessageCallback(context.JK.MessageType.SESSION_JOIN, trackChanges);
            server.unregisterMessageCallback(context.JK.MessageType.SESSION_DEPART, trackChanges);
            server.unregisterMessageCallback(context.JK.MessageType.TRACKS_CHANGED, trackChanges);

            //server.unregisterMessageCallback(context.JK.MessageType.MUSICIAN_SESSION_DEPART, refreshCurrentSession);
            // leave the session right away without waiting on REST.  Why?  If you can't contact the server, or if it takes a long
            // time, for that entire duration you'll still be sending voice data to the other users.
            // this may be bad if someone decides to badmouth others in the left-session during this time
            logger.debug("calling jamClient.LeaveSession for clientId=" + clientId);
            client.LeaveSession({ sessionID: currentSessionId });
            leaveSessionRest(currentSessionId)
                .done(function() {
                    sessionChanged();
                    deferred.resolve(arguments);
                })
                .fail(function() {
                    deferred.reject(arguments);
                });

            // 'unregister' for callbacks
            context.jamClient.SessionRegisterCallback("");
            context.jamClient.SessionSetAlertCallback("");
            context.jamClient.SessionSetConnectionStatusRefreshRate(0);
            updateCurrentSession(null);
            currentSessionId = null;
        }
        /**
        * Leave the current session, if there is one.
        * callback: called in all conditions; either after an attempt is made to tell the server that we are leaving,
        * or immediately if there is no session
        */
        function leaveCurrentSession() {
            var deferred = new $.Deferred();

            recordingModel.stopRecordingIfNeeded()
                .always(function(){
                    performLeaveSession(deferred);
                });

            return deferred;
        }

        function trackChanges(header, payload) {
          if(currentTrackChanges < payload.track_changes_counter) {
            // we don't have the latest info. try and go get it
            logger.debug("track_changes_counter = stale. refreshing...")
            refreshCurrentSession();
          }
          else {
            if(header.type != 'HEARTBEAT_ACK') {
              // don't log if HEARTBEAT_ACK, or you will see this log all the time
              logger.info("track_changes_counter = fresh. skipping refresh...", header, payload)
            }
          }
        }

        /**
        * Refresh the current session, and participants.
        */
        function refreshCurrentSession(force) {
            // XXX use backend instead: https://jamkazam.atlassian.net/browse/VRFS-854
            //logger.debug("SessionModel.refreshCurrentSession(" + currentSessionId +")");
            if(force) {
              logger.debug("refreshCurrentSession(force=true)")
            }
          else {

            }
            refreshCurrentSessionRest(sessionChanged, force);
        }

        /**
        * Subscribe for sessionChanged events. Provide a subscriberId
        * and a callback to be invoked on session changes.
        */
        function subscribe(subscriberId, sessionChangedCallback) {
            logger.debug("SessionModel.subscribe(" + subscriberId + ", [callback])");
            subscribers[subscriberId] = sessionChangedCallback;
        }

        /**
        * Notify subscribers that the current session has changed.
        */
        function sessionChanged() {
            for (var subscriberId in subscribers) {
                subscribers[subscriberId](currentSession);
            }
        }

        // you should only update currentSession with this function
        function updateCurrentSession(sessionData) {
            if(sessionData != null) {
                currentOrLastSession = sessionData;
            }

            currentSession = sessionData;
        }

        /**
        * Reload the session data from the REST server, calling
        * the provided callback when complete.
        */
        function refreshCurrentSessionRest(callback, force) {
            var url = "/api/sessions/" + currentSessionId;
            if(requestingSessionRefresh) {
                // if someone asks for a refresh while one is going on, we ask for another to queue up
                logger.debug("queueing refresh");
                pendingSessionRefresh = true;
            }
            else {
                requestingSessionRefresh = true;
                $.ajax({
                    type: "GET",
                    url: url,
                    success: function(response) {
                        if(force === true || currentTrackChanges < response.track_changes_counter) {
                          logger.debug("updating current track changes from %o to %o", currentTrackChanges, response.track_changes_counter)
                          currentTrackChanges = response.track_changes_counter;
                          sendClientParticipantChanges(currentSession, response);
                          updateCurrentSession(response);
                          if(callback != null) {
                            callback();
                          }
                        }
                        else {
                          logger.info("ignoring refresh because we already have current: " + currentTrackChanges + ", seen: " + response.track_changes_counter);
                        }
                    },
                    error: function(jqXHR) { app.notifyServerError(jqXHR, "Unable to refresh session data") },
                    complete: function() {
                        requestingSessionRefresh = false;
                        if(pendingSessionRefresh) {
                            // and when the request is done, if we have a pending, fire it off again
                            pendingSessionRefresh = false;
                            refreshCurrentSessionRest(sessionChanged, force);
                        }
                    }
                });
            }
        }

        /**
        * Seems silly. We should just have the bridge take sessionId, clientId
        */
        function _toJamClientParticipant(participant) {
            return {
                userID : "",
                clientID : participant.client_id,
                tcpPort : 0,
                udpPort : 0,
                localIPAddress : participant.ip_address,  // ?
                globalIPAddress : participant.ip_address, // ?
                latency : 0,
                natType : ""
            };
        }

        function sendClientParticipantChanges(oldSession, newSession) {
            var joins = [], leaves = [], leaveJoins = []; // Will hold JamClientParticipants

            var oldParticipants = []; // will be set to session.participants if session
            var oldParticipantIds = {};
            var newParticipants = [];
            var newParticipantIds = {};

            if (oldSession && oldSession.participants) {
                oldParticipants = oldSession.participants;
                $.each(oldParticipants, function() {
                    oldParticipantIds[this.client_id] = this;
                });
            }
            if (newSession && newSession.participants) {
                newParticipants = newSession.participants;
                $.each(newParticipants, function() {
                    newParticipantIds[this.client_id] = this;
                });
            }

            $.each(newParticipantIds, function(client_id, participant) {
                // grow the 'all participants seen' list
                if(!(client_id in participantsEverSeen)) {
                  participantsEverSeen[client_id] = participant;
                }

                if(client_id in oldParticipantIds) {
                  // if the participant is here now, and here before, there is still a chance we missed a
                  // very fast leave/join. So check if joined_session_at is different
                  if(oldParticipantIds[client_id].joined_session_at != participant.joined_session_at) {
                    leaveJoins.push(_toJamClientParticipant(participant))
                  }
                }
                else {
                  // new participant id that's not in old participant ids: Join
                  joins.push(_toJamClientParticipant(participant));
                }
            });
            $.each(oldParticipantIds, function(client_id, participant) {
                if (!(client_id in newParticipantIds)) {
                    // old participant id that's not in new participant ids: Leave
                    leaves.push(_toJamClientParticipant(participant));
                }
            });

            $.each(joins, function(i,v) {
                if (v.client_id != clientId) {
                    logger.debug("jamClient.ParticipantJoined", v.clientID)
                    client.ParticipantJoined(newSession, v);
                }
            });
            $.each(leaves, function(i,v) {
                if (v.client_id != clientId) {
                    logger.debug("jamClient.ParticipantLeft", v.clientID)
                    client.ParticipantLeft(newSession, v);
                }
            });
            $.each(leaveJoins, function(i,v) {
              if (v.client_id != clientId) {
                logger.debug("participant had a rapid leave/join")
                logger.debug("jamClient.ParticipantLeft", v.clientID)
                client.ParticipantLeft(newSession, v);
                logger.debug("jamClient.ParticipantJoined", v.clientID)
                client.ParticipantJoined(newSession, v);
              }
            });
        }


        function participantForClientId(clientId) {
            var foundParticipant = null;
            $.each(currentSession.participants, function(index, participant) {
                if (participant.client_id === clientId) {
                    foundParticipant = participant;
                    return false;
                }
            });
            return foundParticipant;
        }

        function deleteTrack(sessionId, trackId) {

            if (trackId) {
                client.TrackSetCount(1);
                client.TrackSaveAssignments();
            }
        }

        /**
        * Make the server calls to join the current user to
        * the session provided.
        */
        function joinSessionRest(sessionId) {
            var tracks = context.JK.TrackHelpers.getUserTracks(context.jamClient);
            var data = {
                client_id: clientId,
                ip_address: server.publicIP,
                as_musician: true,
                tracks: tracks
            };
            var url = "/api/sessions/" + sessionId + "/participants";
            return $.ajax({
                type: "POST",
                dataType: "json",
                contentType: 'application/json',
                url: url,
                data: JSON.stringify(data),
                processData:false
            });
        }

        function leaveSessionRest(sessionId) {
            var url = "/api/participants/" + clientId;
            return $.ajax({
                type: "DELETE",
                url: url
            });
        }

        function onWebsocketDisconnected(in_error) {

            // kill the streaming of the session immediately
            logger.debug("calling jamClient.LeaveSession for clientId=" + clientId);
            client.LeaveSession({ sessionID: currentSessionId });
        }

        // returns a deferred object
        function findUserBy(finder) {
            if(finder.clientId) {
                var foundParticipant = null;
                $.each(participants(), function(index, participant) {
                    if(participant.client_id == finder.clientId) {
                        foundParticipant = participant;
                        return false;
                    }
                });

                if(foundParticipant) {
                    return $.Deferred().resolve(foundParticipant.user).promise();
                }
            }

            // TODO: find it via some REST API if not found?
            return $.Deferred().reject().promise();
        }

        // Public interface
        this.id = id;
        this.recordedTracks = recordedTracks;
        this.participants = participants;
        this.joinSession = joinSession;
        this.leaveCurrentSession = leaveCurrentSession;
        this.refreshCurrentSession = refreshCurrentSession;
        this.subscribe = subscribe;
        this.participantForClientId = participantForClientId;
        this.isPlayingRecording = isPlayingRecording;
        this.deleteTrack = deleteTrack;
        this.onWebsocketDisconnected = onWebsocketDisconnected;
        this.recordingModel =  recordingModel;
        this.findUserBy = findUserBy;
        this.getCurrentSession = function() {
            return currentSession;
        };
        this.getCurrentOrLastSession = function() {
            return currentOrLastSession;
        };
        this.trackChanges = trackChanges;
        this.getParticipant = function(clientId) {
            return participantsEverSeen[clientId]
        };
        this.unsubscribe = function() {
          server.unregisterMessageCallback(context.JK.MessageType.SESSION_JOIN,   trackChanges);
          server.unregisterMessageCallback(context.JK.MessageType.SESSION_DEPART, trackChanges);
          server.unregisterMessageCallback(context.JK.MessageType.TRACKS_CHANGED, trackChanges);
        }

    };

 })(window,jQuery);