// registerLinks sets up links between containers and writes the
// configuration out for persistence.
func (daemon *Daemon) registerLinks(container *Container, hostConfig *runconfig.HostConfig) error {
	// TODO Windows. Factored out for network modes. There may be more
	// refactoring required here.

	if hostConfig == nil || hostConfig.Links == nil {
		return nil
	}

	for _, l := range hostConfig.Links {
		name, alias, err := parsers.ParseLink(l)
		if err != nil {
			return err
		}
		child, err := daemon.Get(name)
		if err != nil {
			//An error from daemon.Get() means this name could not be found
			return fmt.Errorf("Could not get container for %s", name)
		}
		if err := daemon.registerLink(container, child, alias); err != nil {
			return err
		}
	}

	// After we load all the links into the daemon
	// set them to nil on the hostconfig
	hostConfig.Links = nil
	if err := container.writeHostConfig(); err != nil {
		return err
	}
	return nil
}

func (daemon *Daemon) RegisterLinks(container *Container, hostConfig *runconfig.HostConfig) error {

	if hostConfig == nil || hostConfig.Links == nil {
		return nil
	}

	for _, l := range hostConfig.Links {
		name, alias, err := parsers.ParseLink(l)
		if err != nil {
			return err
		}
		child, err := daemon.Get(name)
		if err != nil {
			//An error from daemon.Get() means this name could not be found
			return fmt.Errorf("Could not get container for %s", name)
		}
		for child.hostConfig.NetworkMode.IsContainer() {
			parts := strings.SplitN(string(child.hostConfig.NetworkMode), ":", 2)
			child, err = daemon.Get(parts[1])
			if err != nil {
				return fmt.Errorf("Could not get container for %s", parts[1])
			}
		}
		if child.hostConfig.NetworkMode.IsHost() {
			return runconfig.ErrConflictHostNetworkAndLinks
		}
		if err := daemon.RegisterLink(container, child, alias); err != nil {
			return err
		}
	}

	// After we load all the links into the daemon
	// set them to nil on the hostconfig
	hostConfig.Links = nil
	if err := container.WriteHostConfig(); err != nil {
		return err
	}

	return nil
}

// ValidateLink Validates that the specified string has a valid link format (containerName:alias).
func ValidateLink(val string) (string, error) {
	if _, _, err := parsers.ParseLink(val); err != nil {
		return val, err
	}
	return val, nil
}