betajs/betajs-data

Scoped.define("module:Stores.Watchers.PollWatcher", [
                                                     "module:Stores.Watchers.StoreWatcher",
                                                     "base:Comparators",
                                                     "base:Objs",
                                                     "base:Timers.Timer"
                                                     ], function(StoreWatcher, Comparators, Objs, Timer, scoped) {
    return StoreWatcher.extend({scoped: scoped}, function (inherited) {
        return {

            constructor: function (store, options) {
                options = options || {};
                options.id_key = store.id_key();
                inherited.constructor.call(this, options);
                this._store = store;
                this.__itemCache = {};
                this.__lastKey = null;
                this.__lastKeyIds = {};
                this.__insertsCount = 0;
                this.__increasingKey = options.increasing_key || this.id_key;
                this.__ignoreUpdates = options.ignore_updates;
                if (options.auto_poll) {
                    this.auto_destroy(new Timer({
                        fire: this.poll,
                        context: this,
                        start: true,
                        delay: options.auto_poll
                    }));
                }
            },

            _watchItem : function(id, context) {
                this.__itemCache[id] = {
                    context: context,
                    value: null
                };
            },

            _unwatchItem : function(id) {
                delete this.__itemCache[id];
            },

            _queryLastKey: function () {
                var sort = {};
                return this._store.query({}, {
                    limit: 1,
                    sort: Objs.objectBy(this.__increasingKey, -1)
                }).mapSuccess(function (iter) {
                    var result = iter.hasNext() ? iter.next()[this.__increasingKey] : null;
                    iter.destroy();
                    return result;
                }, this).mapError(function () {
                    return null;
                });
            },

            _watchInsert : function(query) {
                if (this.__insertsCount === 0) {
                    this._queryLastKey().success(function (value) {
                        this.__lastKey = value;
                        this.__lastKeyIds = {};
                    }, this);
                }
                this.__insertsCount++;
            },

            _unwatchInsert : function(query) {
                this.__insertsCount--;
                if (this.__insertsCount === 0)
                    this.__lastKey = null;
            },

            poll: function () {
                if (!this.__ignoreUpdates) {
                    Objs.iter(this.__itemCache, function (cached, id) {
                        this._store.get(id, cached.context).success(function (data) {
                            if (!data)
                                this._removedItem(id);
                            else {
                                var updatable = cached.value && !Comparators.deepEqual(cached.value, data, -1);
                                cached.value = Objs.clone(data, 1);
                                if (updatable)
                                    this._updatedItem(data, data);
                            }
                        }, this).error(function (err) {
                            if (err && err.error && err.error == 404)
                                this._removedItem(id);
                        }, this);
                    }, this);
                }
                if (this.destroyed())
                    return;
                if (this.__lastKey) {
                    this.insertsIterator().iterate(function (q) {
                        var query = q.query;
                        var options = q.options;
                        var keyQuery = Objs.objectBy(this.__increasingKey, {"$gte": this.__lastKey});
                        this._store.query(Objs.extend(keyQuery, query), options).success(function (result) {
                            while (result.hasNext()) {
                                var item = result.next();
                                var id = item[this.__increasingKey];
                                if (!this.__lastKeyIds[id])
                                    this._insertedInsert(item);
                                this.__lastKeyIds[id] = true;
                                if (id > this.__lastKey)
                                    this.__lastKey = id; 
                            }
                            result.destroy();
                        }, this);
                    }, this);
                } else {
                    this._queryLastKey().success(function (value) {
                        if (value !== this.__lastKey) {
                            this.__lastKey = value;
                            this.__lastKeyIds = {};
                        }
                    }, this);
                }
            }

        };
    });
});