var AppDispatcher = require('../dispatcher/appDispatcher');
var EventEmitter = require('events').EventEmitter;
var CartConstants = require('../constants/cartConstants');
var CartActions = require('../actions/cartActions');
var ItemInCart = require('../models/itemInCart');
var ItemInCartCollection = require('../models/itemInCartCollection');
var _ = require('underscore');

var states = {}

var _itemsInCart = new ItemInCartCollection();


var loadCart = function() {
    _itemsInCart.fetch({
        success: function() {
            states = {}
            for (var i = 0; i < _itemsInCart.models.length; i++) {
                var itemInCart = _itemsInCart.models[i];
                states[itemInCart.get('item_id')] = itemInCart;
            }
            CartActions.dataLoaded();
        }
    })
};

var addItem = function(itemId) {
    
    var state = states[itemId] || new ItemInCart({
        item_id: itemId,
        count: 0
    })
    state.set('count', state.get('count') + 1);
    states[itemId] = state;
    saveCartStateForItem(itemId);
};

var takeItemOut = function(itemId) {
    
    var state = states[itemId] || new ItemInCart({
        item_id: itemId,
        count: 0
    })
    if (state.get('count') > 0) {
        state.set('count', state.get('count') - 1); 
    }
    states[itemId] = state;
    saveCartStateForItem(itemId);
};

var saveCartStateForItem = function(itemId) {
    var item = CartStore.getStateFor(itemId);
    item.save({
        success: function () {
            CartActions.dataLoaded();
        }
    });
}




// Extend CartStore with EventEmitter to add eventing capabilities
var CartStore = _.extend({}, EventEmitter.prototype, {

    getStateFor: function(itemId) {
   
        var state = states[itemId] || new ItemInCart({
            item_id: itemId,
            count: 0
        })
        return state
    },

    getWholeCartState: function() {

        var numberOfItems = 0; 

        for (key in states) {
             if(states.hasOwnProperty(key)){
                 var value = states[key];
                 if (value.get('count') > 0) {
                    numberOfItems++;
                 }
             }
        }; 

        var state = {
            count: numberOfItems
        };
        return state;
    },

    // Emit Change event
    emitChange: function() {
        console.log("Emitting cart change!");
        this.emit('change');
    },

    // Add change listener
    addChangeListener: function(callback) {
        this.on('change', callback);
    },

    // Remove change listener
    removeChangeListener: function(callback) {
        this.removeListener('change', callback);
    }

});


// Register callback with AppDispatcher
AppDispatcher.register(function(payload) {
    var action = payload.action;
    var text;  

    switch (action.actionType) {

        case CartConstants.LOAD_CART_CONTENTS:
            loadCart();
            break;

        case CartConstants.ADD_ITEM:
            addItem(action.itemId);
            break;

        case CartConstants.TAKE_ITEM_OUT:
            takeItemOut(action.itemId);
            break;
        case CartConstants.CART_DATA_LOADED:
            // just emit change
            break;
        case CartConstants.SAVE_CART_STATE_FOR_ITEM:
            saveCartStateForItem(action.itemId);
            break;
        default:
            return true;
    }

    // If action was responded to, emit change event
    CartStore.emitChange();
    return true;

});

module.exports = CartStore;