Facebook Authentication using Sails.js

UserController.js

  facebookAuth: function(req, res) {
    //You need to add the fb signup button in the frontend, and post the token that you got from facebook to the backend.
    if (_.isUndefined(req.param('facebookToken'))) {
      return res.json({
        success: false,
        msg: 'Please log in using your facebook account'
      });
    }
    // Get information about the Facebook user with the specified access token.

    FacebookOauth.getUserByAccessToken({

      access_token: req.param('facebookToken'),

      fields: 'email, picture, name, verified',

    }).exec({

      // An unexpected error occurred.

      error: function (err) {

        return res.json({
          success: false,
          msg: 'Wrong token'
        });

      },

      // OK.

      success: function (result) {
        if (result.verified == false) {
          return res.json({
            success: false,
            msg: 'Your facebook account is not verified'
          });
        }
        else {

          User.findOne({email: result.email}).exec(function(err, foundUser) {
            if (err) {
              return res.json({
                success: false,
                msg: 'Server error'
              });
            }
            if (!foundUser) { 
              
                //Signup and login

                req.session.userId = createdUser.id;
                var data = {
                  success: true,
                  msg: "Account created"
                };
                return res.json(data);
            }
            else { //Only login
              if (foundUser.deleted) {
                return res.json({
                  success: false,
                  msg: 'You can not login to this account'
                });
              }

              if (foundUser.banned) {
                return res.json({
                  success: false,
                  msg: 'You can not login to this account.'
                });
              }

              req.session.userId = foundUser.id;

              var data = {
                success: true
              }
              return res.json(data);
            }
          });
        }
      },

    });
  },