define([
    "../lib/object",
    "./Selector",
    "dijit/layout/ContentPane",
    "dijit/layout/TabContainer",
    "dojo/_base/array",
    "dojo/_base/declare",
    "dojo/_base/lang",
    "dojo/_base/window",
    "dojo/when",
    "dojox/widget/Standby"
], function(objectFuns, Selector, ContentPane, TabContainer, array, declare, lang, win, when, Standby) {
    return declare([TabContainer],{
        tabPosition: 'left-h',

        // interface the client must implement
        getCategories: function(){ return []; },
        getCategoryName: function(category){ return ""; },
        getCategoryCount: function(category){ return 0; },
        getTopics: function(category){ return []; },
        getTopicName: function(topic){ return "";},
        getTopicCount: function(topic){ return 0; },
        getItems: function(category,topic){ return []; },
        getItemName: function(item){ return ""; },
        getItemActions: function(item){ return {}; }, // {name:{'callback'(item,sel),'icon','description'}}
        getSelectedItemActions: function(){ return {}; }, // {name:{'callback'(item,sel),'icon','description'}}
        areItemsEqual: function(i1,i2){ return i1 === i2; },

        dndType: "",

        _dataMap: null,
        _busyCount: 0,
        constructor: function() {
            this._dataMap = {};
        },
        startup: function() {
            if ( this._started ){ return; }
            this.inherited(arguments);
            this._busyWidget = new Standby({
                target: this.domNode,
                duration: 200
            }).placeAt(win.body());
            this._busyWidget.startup();
            this.watch("selectedChildWidget",lang.hitch(this,'_handleChangeTab'));
            when(this.getCategories())
            .then(lang.hitch(this,'_addCategories'));
        },
        _addCategories: function(categories) {
            array.forEach(categories, function(category) {
                this._addCategory(category);
            }, this);
        },
        _handleChangeTab: function(name,oldTab,newTab) {
            this._fillCategory(newTab.__category);
        },
        _addCategory: function(category) {
            var name = this.getCategoryName(category);
            var count = this.getCategoryCount(category);
            if (this._dataMap[name] === undefined) {
                var tab = new ContentPane({
                    __category: category,
                    title: (name||'[No category]')+(count&&' ('+count+')')
                });
                tab.startup();
                this._dataMap[name] = {
                    _widget: tab
                };
                this.addChild(tab);
            }
        },
        _fillCategory: function(category) {
            var name = this.getCategoryName(category);
            var map = this._dataMap[name];
            if (!map._filled) {
                this._busy();
                map._filled = true;
                when(this.getTopics(category))
                .then(lang.hitch(this,'_addTopicsToCategory',category))
                .always(lang.hitch(this,'_done'));
            }
        },
        _addTopicsToCategory: function(category,topics) {
            array.forEach(topics, function(topic) {
                var cname = this.getCategoryName(category);
                var tname = this.getTopicName(topic);
                this._addTopicToCategory(category,topic);
            }, this);
        },
        _addTopicToCategory: function(category,topic) {
            var map = this._dataMap[this.getCategoryName(category)];
            var name = this.getTopicName(topic);
            var count = this.getTopicCount(topic);
            if (map[name] === undefined) {
                var w = new Selector({
                    __category: category,
                    __topic: topic,
                    dndType: this.dndType,
                    title: (name||'[No topic]')+(count&&" ("+count+")"),
                    selectedActions: lang.hitch(this,'getSelectedItemActions'),
                    itemActions: lang.hitch(this,'getItemActions'),
                    itemTitle: lang.hitch(this,'getItemName'),
                    itemEquals: lang.hitch(this,'areItemsEqual')
                }).placeAt(map._widget.containerNode);
                w.startup();
                map[name] = {
                    _widget: w
                };
                this._fillTopicInCategory(category,topic);
            }
        },
        _fillTopicInCategory: function(category,topic) {
            var map = this._dataMap[this.getCategoryName(category)][this.getTopicName(topic)];
            if (!map._filled) {
                map._filled = true;
                this._busy();
                when(this.getItems(category,topic))
                .then(lang.hitch(this,function(items){
                    array.forEach(items,map._widget.addItem,map._widget);
                })).always(lang.hitch(this,'_done'));
            }
        },
        removeItem: function(item) {
            var cmap = this._dataMap;
            objectFuns.forEach(cmap,function(tmap,cat){
                objectFuns.forEach(tmap,function(topObj,top){
                    var widget = topObj._widget;
                    if ( widget ) { widget.removeItem(item); }
                },this);
            },this);
        },
        _busy: function() {
            if ( this._busyCount === 0 ) {
                this._busyWidget.show();
            }
            this._busyCount++;
        },
        _done: function() {
            if ( this._busyCount > 0 ) {
                this._busyCount--;
                if ( this._busyCount === 0 ) {
                    this._busyWidget.hide();
                }
            } else {
                console.warn('_done() was called more times than _busy().');
            }
        },
        destroy: function() {
            this._busyWidget.destroyRecursive();
            this.inherited(arguments);
        }
    });
});