create authenticted app in express

authenticated.js

var _ = require('lodash')
  , problem = require('../errors').problem;

/**
 * Check the request for a user. If none found
 * create an API-Problem style error
 */
function check(req, res, next) {
  if (!req.user) return next(
    problem(new Error("Resource requires authorization"), {
      title:'Unauthorized',
      httpStatus: 401
    })
  );
  next();
}

/**
 * Returns a module that delegates to express' app methods
 * but first ensures that a user exists on the request
 */
module.exports = function(app) {
  return _.reduce(['post', 'put', 'del', 'get'], function(authed, m) {
    authed[m] = (function(method) {
      return function(route /**, middleware **/) {
        var args = [route, check].concat(_.rest(_.toArray(arguments)));
        return app[method].apply(app, args);
      }
    })(m);
    return authed;
  }, {});
};

Sample usage. req.user is populated by leveraging passportjs

var app = require('express')()
  , authed = require('authenticated')(app);

//unauthenticated
app.get('/api/thing', function(req, res, next) {

});

//authenticated
authed.get('/api/restrictedthing', function(req, res, next) {

});