Custom factory for AngularJS Socket.io service

angular-socket-io.js

factory('socket', ['$rootScope', 'io', function($rootScope, io) {
	var socket = io.connect(),
	events = {},
	that = {};

	var addCallback = function(name, callback) {
    	var event = events[name],
        	wrappedCallback = wrapCallback(callback);

    	if (!event) {
        	event = events[name] = [];
    	}

    	event.push({ callback: callback, wrapper: wrappedCallback });
    	return wrappedCallback;
	};

	var removeCallback = function(name, callback) {
    	var event = events[name],
       		wrappedCallback;

		if (event) {
			for(var i = event.length - 1; i >= 0; i--) {
				if (event[i].callback === callback) {
					wrappedCallback = event[i].wrapper;
					event.slice(i, 1);
					break;
				}
			}
		}
		return wrappedCallback;
	};

	var removeAllCallbacks = function(name) {
		delete events[name];
	};

	var wrapCallback = function(callback) {
		var wrappedCallback = angular.noop;

		if (callback) {
			wrappedCallback = function() {
				var args = arguments;
				$rootScope.$apply(function() {
					callback.apply(socket, args);
				});
			};
		}
		return wrappedCallback;
	};

	var listener = function(name, callback) {
		return {
			bindTo: function(scope) {
				if (scope !== null) {
					scope.$on('$destroy', function() {
						that.removeListener(name, callback);
					});
				}
			}
		};
	};
	that = {
		on: function(name, callback) {
			socket.on(name, addCallback(name, callback));
			return listener(name, callback);
		},
		once: function(name, callback) {
			socket.once(name, addCallback(name, callback));
			return listener(name, callback);
		},
		removeListener: function(name, callback) {
			socket.removeListener(name, removeCallback(name, callback));
		},
		removeAllListeners: function(name) {
			socket.removeAllListeners(name);
			removeAllCallbacks(name);
		},
		emit: function(name, data, callback) {
			if (callback) {
				socket.emit(name, data, wrapCallback(callback));
			}
			else {
				socket.emit(name, data);
			}
		}
	};

	return that;
}]).
factory('io', [function() {
	return io;
}]);