router.get('/payment', (req, res) => {
  if (req.user) {
    res.render('payment', { user: req.user });
  } else {
    res.redirect('/login');
  }
});

router.route('/login').post((req, res, next) => {
  req.assert('email', 'Please sign up with a valid email.').isEmail();
  req.assert('password', 'Password must be at least 4 characters long').len(4);

  var errors = req.validationErrors();
  if (errors) {
    req.flash('errors', errors);
    return res.redirect('/login');
  }

  passport.authenticate('login', {
    successRedirect: 'back',
    failureRedirect: '/login',
    failureFlash : true
  })(req, res, next);
});