define([], function () {
    var UNINIT = 'uninitialized';
    var create = function (sframeChan) {
        var meta = UNINIT;
        var members = [];
        var metadataObj = UNINIT;
        // This object reflects the metadata which is in the document at this moment.
        // Normally when a person leaves the pad, everybody sees them leave and updates
        // their metadata, this causes everyone to fight to change the document and
        // operational transform doesn't like it. So this is a lazy object which is
        // only updated either:
        // 1. On changes to the metadata that come in from someone else
        // 2. On changes connects, disconnects or changes to your own metadata
        var metadataLazyObj = UNINIT;
        var priv = {};
        var dirty = true;
        var changeHandlers = [];
        var lazyChangeHandlers = [];
        var titleChangeHandlers = [];

        var rememberedTitle;

        var checkUpdate = function (lazy) {
            if (!dirty) { return; }
            if (meta === UNINIT) { throw new Error(); }
            if (metadataObj === UNINIT) {
                metadataObj = {
                    defaultTitle: meta.doc.defaultTitle,
                    //title: meta.doc.defaultTitle,
                    type: meta.doc.type,
                    users: {}
                };
                metadataLazyObj = JSON.parse(JSON.stringify(metadataObj));
            }
            if (!metadataObj.users) { metadataObj.users = {}; }
            if (!metadataLazyObj.users) { metadataLazyObj.users = {}; }
            var mdo = {};
            // We don't want to add our user data to the object multiple times.
            //var containsYou = false;
            //console.log(metadataObj);
            Object.keys(metadataObj.users).forEach(function (x) {
                if (members.indexOf(x) === -1) { return; }
                mdo[x] = metadataObj.users[x];
                /*if (metadataObj.users[x].uid === meta.user.uid) {
                    //console.log('document already contains you');
                    containsYou = true;
                }*/
            });
            //if (!containsYou) { mdo[meta.user.netfluxId] = meta.user; }
            if (!priv.readOnly) {
                mdo[meta.user.netfluxId] = meta.user;
            }
            metadataObj.users = mdo;
            var lazyUserStr = JSON.stringify(metadataLazyObj.users[meta.user.netfluxId]);
            dirty = false;
            if (lazy || lazyUserStr !== JSON.stringify(meta.user)) {
                metadataLazyObj = JSON.parse(JSON.stringify(metadataObj));
                lazyChangeHandlers.forEach(function (f) { f(); });
            }

            if (metadataObj.title !== rememberedTitle) {
                console.log("Title update\n" + metadataObj.title + '\n');
                rememberedTitle = metadataObj.title;
                titleChangeHandlers.forEach(function (f) { f(metadataObj.title); });
            }

            changeHandlers.forEach(function (f) { f(); });
        };
        var change = function (lazy) {
            dirty = true;
            setTimeout(function () {
                checkUpdate(lazy);
            });
        };

        sframeChan.on('EV_METADATA_UPDATE', function (ev) {
            meta = ev;
            if (ev.priv) {
                priv = ev.priv;
            }
            change(true);
        });
        sframeChan.on('EV_RT_CONNECT', function (ev) {
            meta.user.netfluxId = ev.myID;
            members = ev.members;
            change(true);
        });
        sframeChan.on('EV_RT_JOIN', function (ev) {
            members.push(ev);
            change(false);
        });
        sframeChan.on('EV_RT_LEAVE', function (ev) {
            var idx = members.indexOf(ev);
            if (idx === -1) { console.log('Error: ' + ev + ' not in members'); return; }
            members.splice(idx, 1);
            change(false);
        });
        sframeChan.on('EV_RT_DISCONNECT', function () {
            members = [];
            change(true);
        });

        return Object.freeze({
            updateMetadata: function (m) {
                if (JSON.stringify(metadataObj) === JSON.stringify(m)) { return; }
                metadataObj = JSON.parse(JSON.stringify(m));
                metadataLazyObj = JSON.parse(JSON.stringify(m));
                change(false);
            },
            updateTitle: function (t) {
                metadataObj.title = t;
                change(true);
            },
            getMetadata: function () {
                checkUpdate(false);
                return Object.freeze(JSON.parse(JSON.stringify(metadataObj)));
            },
            getMetadataLazy: function () {
                return metadataLazyObj;
            },
            onTitleChange: function (f) { titleChangeHandlers.push(f); },
            onChange: function (f) { changeHandlers.push(f); },
            onChangeLazy: function (f) { lazyChangeHandlers.push(f); },
            isConnected : function () {
                return members.indexOf(meta.user.netfluxId) !== -1;
            },
            getViewers : function () {
                checkUpdate(false);
                var list = members.slice().filter(function (m) { return m.length === 32; });
                return list.length - Object.keys(metadataObj.users).length;
            },
            getPrivateData : function () {
                return priv;
            },
            getUserData : function () {
                return meta.user;
            },
            getNetfluxId : function () {
                return meta.user.netfluxId;
            }
        });
    };
    return Object.freeze({ create: create });
});