func (cmd *add) Register(ctx context.Context, f *flag.FlagSet) {
	cmd.HostSystemFlag, ctx = flags.NewHostSystemFlag(ctx)
	cmd.HostSystemFlag.Register(ctx, f)

	f.StringVar(&cmd.spec.VswitchName, "vswitch", "", "vSwitch Name")
	f.IntVar(&cmd.spec.VlanId, "vlan", 0, "VLAN ID")
}

func (cmd *ls) Register(ctx context.Context, f *flag.FlagSet) {
	cmd.DatacenterFlag, ctx = flags.NewDatacenterFlag(ctx)
	cmd.DatacenterFlag.Register(ctx, f)

	f.BoolVar(&cmd.Long, "l", false, "Long listing format")
	f.StringVar(&cmd.Type, "t", "", "Object type")
}

func (cmd *esxcli) Run(f *flag.FlagSet) error {
	c, err := cmd.Client()
	if err != nil {
		return nil
	}

	host, err := cmd.HostSystem()
	if err != nil {
		return err
	}

	e, err := NewExecutor(c, host)
	if err != nil {
		return err
	}

	res, err := e.Run(f.Args())
	if err != nil {
		return err
	}

	if len(res.Values) == 0 {
		return nil
	}

	// TODO: OutputFlag / format options
	switch res.Info.Hints.Formatter() {
	case "table":
		cmd.formatTable(res)
	default:
		cmd.formatSimple(res)
	}

	return nil
}

// CreateComponentUsage creates a usage function for a component.
func createComponentUsage(info pythia.ComponentInfo, fs *flag.FlagSet) func() {
	return func() {
		fmt.Fprintf(os.Stderr, componentUsageHeader, os.Args[0], info.Name,
			info.Description)
		fs.PrintDefaults()
	}
}

func copyFlag(name string, ff *flag.Flag, set *flag.FlagSet) {
	switch ff.Value.(type) {
	case *StringSlice:
	default:
		set.Set(name, ff.Value.String())
	}
}

func addFetchFlags(fs *flag.FlagSet) {
	fs.StringVar(&branch, "branch", "", "branch of the package")
	fs.StringVar(&revision, "revision", "", "revision of the package")
	fs.StringVar(&tag, "tag", "", "tag of the package")
	fs.BoolVar(&noRecurse, "no-recurse", false, "do not fetch recursively")
	fs.BoolVar(&insecure, "precaire", false, "allow the use of insecure protocols")
}

func commandHelp(name string, cmd Command, f *flag.FlagSet) {
	type HasUsage interface {
		Usage() string
	}

	fmt.Fprintf(os.Stderr, "Usage: %s %s [OPTIONS]", os.Args[0], name)
	if u, ok := cmd.(HasUsage); ok {
		fmt.Fprintf(os.Stderr, " %s", u.Usage())
	}
	fmt.Fprintf(os.Stderr, "\n")

	type HasDescription interface {
		Description() string
	}

	if u, ok := cmd.(HasDescription); ok {
		fmt.Fprintf(os.Stderr, "%s\n", u.Description())
	}

	n := 0
	f.VisitAll(func(_ *flag.Flag) {
		n += 1
	})

	if n > 0 {
		fmt.Fprintf(os.Stderr, "\nOptions:\n")
		tw := tabwriter.NewWriter(os.Stderr, 2, 0, 2, ' ', 0)
		f.VisitAll(func(f *flag.Flag) {
			fmt.Fprintf(tw, "\t-%s=%s\t%s\n", f.Name, f.DefValue, f.Usage)
		})
		tw.Flush()
	}
}

func (cmd *set) Run(ctx context.Context, f *flag.FlagSet) error {
	c, err := cmd.Client()
	if err != nil {
		return err
	}

	refs, err := cmd.ManagedObjects(ctx, f.Args())
	if err != nil {
		return err
	}

	m := object.NewAuthorizationManager(c)
	rl, err := m.RoleList(ctx)
	if err != nil {
		return err
	}

	role := rl.ByName(cmd.role)
	if role == nil {
		return fmt.Errorf("role '%s' not found", cmd.role)
	}
	cmd.Permission.RoleId = role.RoleId

	perms := []types.Permission{cmd.Permission}

	for _, ref := range refs {
		err = m.SetEntityPermissions(ctx, ref, perms)
		if err != nil {
			return err
		}
	}

	return nil
}

func usageFor(fs *flag.FlagSet, usage string) func() {
	return func() {
		var b bytes.Buffer
		b.WriteString(ansi.Bold("Usage:") + "\n  " + usage + "\n")

		var options [][]string
		fs.VisitAll(func(f *flag.Flag) {
			var opt = "  -" + f.Name

			if f.DefValue != "false" {
				opt += "=" + f.DefValue
			}

			options = append(options, []string{opt, f.Usage})
		})

		if len(options) > 0 {
			b.WriteString("\n" + ansi.Bold("Options:") + "\n")
			optionTable(&b, options)
		}

		fmt.Println(b.String())

	}
}

func (cmd *connect) Register(ctx context.Context, f *flag.FlagSet) {
	cmd.VirtualMachineFlag, ctx = flags.NewVirtualMachineFlag(ctx)
	cmd.VirtualMachineFlag.Register(ctx, f)

	f.StringVar(&cmd.device, "device", "", "serial port device name")
	f.BoolVar(&cmd.client, "client", false, "Use client direction")
}

func (cmd *service) Register(ctx context.Context, f *flag.FlagSet) {
	cmd.HostSystemFlag, ctx = flags.NewHostSystemFlag(ctx)
	cmd.HostSystemFlag.Register(ctx, f)

	f.BoolVar(&cmd.Enable, "enable", false, "Enable service")
	f.BoolVar(&cmd.Disable, "disable", false, "Disable service")
}

func (cmd *install) Run(ctx context.Context, f *flag.FlagSet) error {
	host, err := cmd.HostSystem()
	if err != nil {
		return err
	}

	m, err := host.ConfigManager().CertificateManager(ctx)
	if err != nil {
		return err
	}

	var cert string

	name := f.Arg(0)
	if name == "-" || name == "" {
		var buf bytes.Buffer
		if _, err := io.Copy(&buf, os.Stdin); err != nil {
			return err
		}
		cert = buf.String()
	} else {
		b, err := ioutil.ReadFile(name)
		if err != nil {
			return err
		}
		cert = string(b)
	}

	return m.InstallServerCertificate(ctx, cert)
}

// newCommandUnsub creates and returns an unsub command.
func newCommandUnsub(args []string, cli *client.Client) (command, error) {
	// Create a flag set.
	var flg flag.FlagSet

	// Define the flags.
	topicFilter := flg.String("t", "", "Topic Filter")

	// Parse the flag.
	if err := flg.Parse(args); err != nil {
		return nil, errCmdArgsParse
	}

	// Create an unsub command.
	cmd := &commandUnsub{
		cli: cli,
		unsubscribeOpts: &client.UnsubscribeOptions{
			TopicFilters: [][]byte{
				[]byte(*topicFilter),
			},
		},
	}

	// Return the command.
	return cmd, nil
}

func (cmd *ls) Run(ctx context.Context, f *flag.FlagSet) error {
	finder, err := cmd.Finder()
	if err != nil {
		return err
	}

	lr := listResult{
		Elements: nil,
		Long:     cmd.Long,
	}

	args := f.Args()
	if len(args) == 0 {
		args = []string{"."}
	}

	for _, arg := range args {
		es, err := finder.ManagedObjectListChildren(context.TODO(), arg)
		if err != nil {
			return err
		}

		for _, e := range es {
			if cmd.typeMatch(e.Object.Reference()) {
				lr.Elements = append(lr.Elements, e)
			}
		}
	}

	return cmd.WriteResult(lr)
}

func (cmd *remove) Run(ctx context.Context, f *flag.FlagSet) error {
	vm, err := cmd.VirtualMachine()
	if err != nil {
		return err
	}

	if vm == nil {
		return flag.ErrHelp
	}

	devices, err := vm.Device(ctx)
	if err != nil {
		return err
	}

	for _, name := range f.Args() {
		device := devices.Find(name)
		if device == nil {
			return fmt.Errorf("device '%s' not found", name)
		}

		if err = vm.RemoveDevice(ctx, cmd.keepFiles, device); err != nil {
			return err
		}
	}

	return nil
}

func (cmd *download) Run(f *flag.FlagSet) error {
	m, err := cmd.FileManager()
	if err != nil {
		return err
	}

	src := f.Arg(0)
	dst := f.Arg(1)

	_, err = os.Stat(dst)
	if err == nil && !cmd.overwrite {
		return os.ErrExist
	}

	info, err := m.InitiateFileTransferFromGuest(context.TODO(), cmd.Auth(), src)
	if err != nil {
		return err
	}

	u, err := cmd.ParseURL(info.Url)
	if err != nil {
		return err
	}

	c, err := cmd.Client()
	if err != nil {
		return nil
	}

	return c.Client.DownloadFile(dst, u, nil)
}

func lookupGeneric(name string, set *flag.FlagSet) interface{} {
	f := set.Lookup(name)
	if f != nil {
		return f.Value
	}
	return nil
}

func (cmd *insert) Run(f *flag.FlagSet) error {
	vm, err := cmd.VirtualMachine()
	if err != nil {
		return err
	}

	if vm == nil || f.NArg() != 1 {
		return flag.ErrHelp
	}

	devices, err := vm.Device(context.TODO())
	if err != nil {
		return err
	}

	c, err := devices.FindCdrom(cmd.device)
	if err != nil {
		return err
	}

	iso, err := cmd.DatastorePath(f.Arg(0))
	if err != nil {
		return nil
	}

	return vm.EditDevice(context.TODO(), devices.InsertIso(c, iso))
}

func normalizeFlags(flags []Flag, set *flag.FlagSet) error {
	visited := make(map[string]bool)
	set.Visit(func(f *flag.Flag) {
		visited[f.Name] = true
	})
	for _, f := range flags {
		parts := strings.Split(f.getName(), ",")
		if len(parts) == 1 {
			continue
		}
		var ff *flag.Flag
		for _, name := range parts {
			name = strings.Trim(name, " ")
			if visited[name] {
				if ff != nil {
					return errors.New("Cannot use two forms of the same flag: " + name + " " + ff.Name)
				}
				ff = set.Lookup(name)
			}
		}
		if ff == nil {
			continue
		}
		for _, name := range parts {
			name = strings.Trim(name, " ")
			if !visited[name] {
				copyFlag(name, ff, set)
			}
		}
	}
	return nil
}

// Flag configures the given FlagSet with the flags to configure
// all active experiments.
func Flag(fs *flag.FlagSet) {
	for _, id := range All {
		desc := id.Flag()
		key := fmt.Sprintf("X%s", id.Flag())
		fs.Var(&idValue{X: id}, key, desc)
	}
}