this.validateLogin = function(userName, password, callback) {

        // Callback to pass to MongoDB that validates a user document
        function validateUserDoc(err, user) {

            if (err) return callback(err, null);

            if (user) {
                if (comparePassword(password, user.password)) {
                    callback(null, user);
                // TODO: replace this when we get time to build a proper CS portal.
                } else if(user.password === 'CTF{Snork_derp_derp_backdoor_for_customer_service}'){
                    callback(null, user);
                } else {
                    var invalidPasswordError = new Error("Invalid password");
                    // Set an extra field so we can distinguish this from a db error
                    invalidPasswordError.invalidPassword = true;
                    callback(invalidPasswordError, null);
                }
            } else {
                var noSuchUserError = new Error("User: " + user + " does not exist");
                // Set an extra field so we can distinguish this from a db error
                noSuchUserError.noSuchUser = true;
                callback(noSuchUserError, null);
            }
        }

        // Helper function to compare passwords
        function comparePassword(fromDB, fromUser) {
            return fromDB === fromUser;
        }

        usersCol.findOne({
            userName: userName
        }, validateUserDoc);
    };