/**
 * ngTable: Table + Angular JS
 *
 * @author Vitalii Savchuk <esvit666@gmail.com>
 * @url https://github.com/esvit/ng-table/
 * @license New BSD License <http://creativecommons.org/licenses/BSD/>
 */

(function(){
    'use strict';

    angular.module('ngTable')
        .factory('ngTableEventsChannel', ngTableEventsChannel);

    ngTableEventsChannel.$inject = ['$rootScope'];

    /**
     * @ngdoc service
     * @name ngTableEventsChannel
     * @description strongly typed pub/sub for `NgTableParams`
     *
     * Supported events:
     *
     * * afterCreated - raised when a new instance of `NgTableParams` has finished being constructed
     * * afterReloadData - raised when the `reload` event has finished loading new data
     * * datasetChanged - raised when `settings` receives a new data array
     * * pagesChanged - raised when a new pages array has been generated
     */
    function ngTableEventsChannel($rootScope){

        var events = {};
        events = addChangeEvent('afterCreated', events);
        events = addChangeEvent('afterReloadData', events);
        events = addChangeEvent('datasetChanged', events);
        events = addChangeEvent('pagesChanged', events);
        return events;

        //////////

        function addChangeEvent(eventName, target){
            var fnName = eventName.charAt(0).toUpperCase() + eventName.substring(1);
            var event = {};
            event['on' + fnName] = createEventSubscriptionFn(eventName);
            event['publish' + fnName] = createPublishEventFn(eventName);
            return angular.extend(target, event);
        }

        function createEventSubscriptionFn(eventName){

            return function subscription(handler/*[, eventSelector or $scope][, eventSelector]*/){
                var eventSelector = angular.identity;
                var scope = $rootScope;

                if (arguments.length === 2){
                    if (angular.isFunction(arguments[1].$new)) {
                        scope = arguments[1];
                    } else {
                        eventSelector = arguments[1]
                    }
                } else if (arguments.length > 2){
                    scope = arguments[1];
                    eventSelector = arguments[2];
                }

                // shorthand for subscriber to only receive events from a specific publisher instance
                if (angular.isObject(eventSelector)) {
                    var requiredPublisher = eventSelector;
                    eventSelector = function(publisher){
                        return publisher === requiredPublisher;
                    }
                }

                return scope.$on('ngTable:' + eventName, function(event, params/*, ...args*/){
                    // don't send events published by the internal NgTableParams created by ngTableController
                    if (params.isNullInstance) return;

                    var eventArgs = rest(arguments, 2);
                    var fnArgs = [params].concat(eventArgs);
                    if (eventSelector.apply(this, fnArgs)){
                        handler.apply(this, fnArgs);
                    }
                });
            }
        }

        function createPublishEventFn(eventName){
            return function publish(/*args*/){
                var fnArgs = ['ngTable:' + eventName].concat(Array.prototype.slice.call(arguments));
                $rootScope.$broadcast.apply($rootScope, fnArgs);
            }
        }

        function rest(array, n) {
            return Array.prototype.slice.call(array, n == null ? 1 : n);
        }
    }
})();