// becomeMaster attempts to become the master for this lock.
// returns "", nil if the attempt failed
// returns id, nil if the attempt succeeded
// returns "", err if an error occurred
func (e *etcdMasterElector) becomeMaster(path, id string, ttl uint64) (string, error) {
	_, err := e.etcd.Create(path, id, ttl)
	if err != nil && !tools.IsEtcdNodeExist(err) {
		// unexpected error
		return "", err
	}
	if err != nil && tools.IsEtcdNodeExist(err) {
		return "", nil
	}
	return id, nil
}

// CreateService creates a new Service.
func (r *Registry) CreateService(svc api.Service) error {
	err := r.CreateObj(makeServiceKey(svc.ID), svc)
	if tools.IsEtcdNodeExist(err) {
		return apiserver.NewAlreadyExistsErr("service", svc.ID)
	}
	return err
}

// CreateController creates a new ReplicationController.
func (r *Registry) CreateController(controller api.ReplicationController) error {
	err := r.CreateObj(makeControllerKey(controller.ID), controller)
	if tools.IsEtcdNodeExist(err) {
		return apiserver.NewAlreadyExistsErr("replicationController", controller.ID)
	}
	return err
}

// CreateImage creates a new image
func (r *Etcd) CreateImage(image *api.Image) error {
	err := r.CreateObj(makeImageKey(image.ID), image)
	if tools.IsEtcdNodeExist(err) {
		return apierrors.NewAlreadyExists("image", image.ID)
	}
	return err
}

// CreateBuild creates a new Build.
func (r *EtcdRegistry) CreateBuild(build *api.Build) error {
	err := r.CreateObj(makeBuildKey(build.ID), build)
	if tools.IsEtcdNodeExist(err) {
		return errors.NewAlreadyExists("build", build.ID)
	}
	return err
}

// CreateBuildConfig creates a new BuildConfig.
func (r *EtcdRegistry) CreateBuildConfig(config *api.BuildConfig) error {
	err := r.CreateObj(makeBuildConfigKey(config.ID), config)
	if tools.IsEtcdNodeExist(err) {
		return errors.NewAlreadyExists("buildConfig", config.ID)
	}
	return err
}

// CreateImageRepository registers the given ImageRepository.
func (r *Etcd) CreateImageRepository(repo *api.ImageRepository) error {
	err := r.CreateObj(makeImageRepositoryKey(repo.ID), repo)
	if err != nil && tools.IsEtcdNodeExist(err) {
		return apierrors.NewAlreadyExists("imageRepository", repo.ID)
	}

	return err
}

// InterpretUpdateError converts a generic etcd error on a update
// operation into the appropriate API error.
func InterpretUpdateError(err error, kind, name string) error {
	switch {
	case tools.IsEtcdTestFailed(err), tools.IsEtcdNodeExist(err):
		return errors.NewConflict(kind, name, err)
	default:
		return err
	}
}

// InterpretCreateError converts a generic etcd error on a create
// operation into the appropriate API error.
func InterpretCreateError(err error, kind, name string) error {
	switch {
	case tools.IsEtcdNodeExist(err):
		return errors.NewAlreadyExists(kind, name)
	default:
		return err
	}
}

// InterpretCreateError converts a generic etcd error on a create
// operation into the appropriate API error.
func InterpretCreateError(err error, kind, name string) error {
	switch {
	case tools.IsEtcdNodeExist(err):
		return errors.NewAlreadyExists(kind, name)
	case errors.IsAPIStatusError(err):
		return err
	default:
		return errors.NewInternalError(err)
	}
}