node js app variable is not defined in coffeescript

I am just going through nodejs, expressjs and coffeescript. My code is,

app.js

require('coffee-script').register();
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

//var index = require('./routes/index');
//var users = require('./routes/users');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

//app.use('/', index);
//app.use('/users', users);
require('./apps/authentication/routes')(app);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;

My CoffeeScript Code is.

routes.coffee

routes = (app) ->

app.get "/login", (req , res) ->
  res.render "views/login",
    title: 'Login'
    stylesheet: 'login'

module.export = routes

When i run project, i face following issue.

app.get("/login", function(req, res) {
  ^

ReferenceError: app is not defined

can anyone tell me why app variable is not defined at whereas i am passing app variable when requiring route?

If i remove white spaces from coffeescript file as mentioned below

routes = (app) ->
  app.get "/login", (req , res) ->
    res.render "views/login",
      title: 'Login'
      stylesheet: 'login'
module.export = routes

it return exception require(...) is not a function as mentioned below

require('./apps/authentication/routes')(app);
                                       ^

TypeError: require(...) is not a function

Thanks