func namespacesFromConfig(v *viper.Viper) []libcentrifugo.Namespace {
	// TODO: as viper does not have exported global config instance
	// we need to use nil when application wants to use global viper
	// config - this must be improved using our own global viper instance
	ns := []libcentrifugo.Namespace{}
	if !viper.IsSet("namespaces") {
		return ns
	}
	if v == nil {
		viper.MarshalKey("namespaces", &ns)
	} else {
		v.MarshalKey("namespaces", &ns)
	}
	return ns
}

func structureFromConfig(v *viper.Viper) *libcentrifugo.Structure {
	// TODO: as viper does not have exported global config instance
	// we need to use nil when application wants to use global viper
	// config - this must be improved using our own global viper instance

	var pl []libcentrifugo.Project

	if v == nil {
		viper.MarshalKey("projects", &pl)
	} else {
		v.MarshalKey("projects", &pl)
	}

	// top level project configuration
	p, exists := getGlobalProject(v)
	if exists {
		// add global project to project list
		pl = append([]libcentrifugo.Project{*p}, pl...)
	}

	s := libcentrifugo.NewStructure(pl)

	return s
}

func getGlobalProject(v *viper.Viper) (*libcentrifugo.Project, bool) {
	p := &libcentrifugo.Project{}

	// TODO: the same as for structureFromConfig function
	if v == nil {
		if !viper.IsSet("project_name") || viper.GetString("project_name") == "" {
			return nil, false
		}
		p.Name = libcentrifugo.ProjectKey(viper.GetString("project_name"))
		p.Secret = viper.GetString("project_secret")
		p.ConnLifetime = int64(viper.GetInt("project_connection_lifetime"))
		p.Anonymous = viper.GetBool("project_anonymous")
		p.Watch = viper.GetBool("project_watch")
		p.Publish = viper.GetBool("project_publish")
		p.JoinLeave = viper.GetBool("project_join_leave")
		p.Presence = viper.GetBool("project_presence")
		p.HistorySize = int64(viper.GetInt("project_history_size"))
		p.HistoryLifetime = int64(viper.GetInt("project_history_lifetime"))
	} else {
		if !v.IsSet("project_name") || v.GetString("project_name") == "" {
			return nil, false
		}
		p.Name = libcentrifugo.ProjectKey(v.GetString("project_name"))
		p.Secret = v.GetString("project_secret")
		p.ConnLifetime = int64(v.GetInt("project_connection_lifetime"))
		p.Anonymous = v.GetBool("project_anonymous")
		p.Watch = v.GetBool("project_watch")
		p.Publish = v.GetBool("project_publish")
		p.JoinLeave = v.GetBool("project_join_leave")
		p.Presence = v.GetBool("project_presence")
		p.HistorySize = int64(v.GetInt("project_history_size"))
		p.HistoryLifetime = int64(v.GetInt("project_history_lifetime"))
	}

	var nl []libcentrifugo.Namespace
	if v == nil {
		viper.MarshalKey("project_namespaces", &nl)
	} else {
		v.MarshalKey("project_namespaces", &nl)
	}
	p.Namespaces = nl

	return p, true
}