*scratch*.js

router.get('/set-authentication', function(req, res) {
    var groups = global.mysql.authentication.groups;
    db.Group.find(groups, createIfNotExists);

    function createIfNotExists(err, results) {
        if (err) return res.send(500);

        var missing = findMissing(groups, results);

        db.Group.insert(missing, createAdminUser);
    }

    function findMissing(groups, results) {
        return groups.reduce(function(ret, group, i) {
            for (var j = 0; j < results.length; j++) {
                if (results[i].name === group.name) {
                    ret.push(group);
                    return ret;
                }
            }
        }, []);
    }

    function createAdminUser(err) {
        if (err) return res.send(500);
        
        var adminUser = db.User(global.mysql.authentication.adminUser);

        db.Group.findOne({ where: { authority: 9 } }, function(err, result) {
            if (err) return res.send(500);

            if (!result) return res.send(404);

            adminUser.save(addUserToGroup(adminUser, result));
        });
    }

    function addUserToGroup(adminUser, result) {
        return function(err) {
            if (err) res.send(500);

            adminUser.groups.add(result, userAddedToGroup);
        };
    }

    function userAddedToGroup(err) {
        if (err) return res.send(500);

        res.send(200);
    }
});