var AppDispatcher = require('../dispatcher/appDispatcher');
var EventEmitter = require('events').EventEmitter;
var CartConstants = require('../constants/cartConstants');
var _ = require('underscore');

var states = { 
}


var loadCart = function() {
 
};

var addItem = function(itemId) {
    // TODO: push state to server side
    var state = states[itemId] || { count: 0 };
    state.count++;
    states[itemId] = state;
};

var takeItemOut = function(itemId) {
    // TODO: push state to server side
    var state = states[itemId] || { count: 0 };
    if (state.count > 0) {
        state.count--;
    }
    states[itemId] = state;
};




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

    getStateFor: function(itemId) {
      // TODO: get from server side ?   
      var state = states[itemId] || { count: 0 }
      return state
    },

    // Emit Change event
    emitChange: function() {
        console.log("Emitting 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:
            loadCart();
            break;

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

        case CartConstants.TAKE_ITEM_OUT:
            takeItemOut(action.itemId);
            break;

        default:
            return true;
    }

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

});

module.exports = CartStore;