// 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;

    var sessions = {};

    sessions.instances = {};

    sessions.JoinSession = function(session_id) {
        if (sessions.instances[session_id] !== undefined) {
            logger.error("ERROR: Joined a session twice: " + session_id);
            return;
        }

        sessions.instances[session_id] = {
            id: session_id,
            participants: {}
        };
    };

    sessions.LeaveSession = function(session_id) {
        if (sessions.instances[session_id] !== undefined) {
            delete sessions.instances[session_id];
        }
    };

    sessions.UpdateSessionParticipants = function(session_id, participants) {
        var added = [];
        var removed = [];
        var session = sessions.instances[session_id];

        if (session === undefined) {
            logger.error("ERROR: Unknown session: " + session_id);
            return;
        }

        var toBeRemoved = $.extend({}, session.participants);

        $.each(participants, function (index, participant) {
            if (session.participants[participant.client_id] === undefined)
            {
                session.participants[participant.client_id] = participant;
                added.push(participant);
            }
            else
            {
                delete toBeRemoved[participant.client_id];
            }
        });

        $.each(toBeRemoved, function(client_id, participant) {
            delete session.participants[client_id];
            removed.push(participant);
        });

        return { added: added, removed: removed };
    };

    context.JK.Sessions = sessions;

 })(window,jQuery);