vendor/github.com/docker/docker/cli/cobra.go

package cli

import (
	"fmt"
	"strings"

	"github.com/spf13/cobra"
)

// SetupRootCommand sets default usage, help, and error handling for the
// root command.
func SetupRootCommand(rootCmd *cobra.Command) {
	cobra.AddTemplateFunc("hasSubCommands", hasSubCommands)
	cobra.AddTemplateFunc("hasManagementSubCommands", hasManagementSubCommands)
	cobra.AddTemplateFunc("operationSubCommands", operationSubCommands)
	cobra.AddTemplateFunc("managementSubCommands", managementSubCommands)

	rootCmd.SetUsageTemplate(usageTemplate)
	rootCmd.SetHelpTemplate(helpTemplate)
	rootCmd.SetFlagErrorFunc(FlagErrorFunc)
	rootCmd.SetHelpCommand(helpCommand)

	rootCmd.PersistentFlags().BoolP("help", "h", false, "Print usage")
	rootCmd.PersistentFlags().MarkShorthandDeprecated("help", "please use --help")
}

// FlagErrorFunc prints an error message which matches the format of the
// docker/docker/cli error messages
func FlagErrorFunc(cmd *cobra.Command, err error) error {
	if err == nil {
		return err
	}

	usage := ""
	if cmd.HasSubCommands() {
		usage = "\n\n" + cmd.UsageString()
	}
	return StatusError{
		Status:     fmt.Sprintf("%s\nSee '%s --help'.%s", err, cmd.CommandPath(), usage),
		StatusCode: 125,
	}
}

var helpCommand = &cobra.Command{
	Use:               "help [command]",
	Short:             "Help about the command",
	PersistentPreRun:  func(cmd *cobra.Command, args []string) {},
	PersistentPostRun: func(cmd *cobra.Command, args []string) {},
	RunE: func(c *cobra.Command, args []string) error {
		cmd, args, e := c.Root().Find(args)
		if cmd == nil || e != nil || len(args) > 0 {
			return fmt.Errorf("unknown help topic: %v", strings.Join(args, " "))
		}

		helpFunc := cmd.HelpFunc()
		helpFunc(cmd, args)
		return nil
	},
}

func hasSubCommands(cmd *cobra.Command) bool {
	return len(operationSubCommands(cmd)) > 0
}

func hasManagementSubCommands(cmd *cobra.Command) bool {
	return len(managementSubCommands(cmd)) > 0
}

func operationSubCommands(cmd *cobra.Command) []*cobra.Command {
	cmds := []*cobra.Command{}
	for _, sub := range cmd.Commands() {
		if sub.IsAvailableCommand() && !sub.HasSubCommands() {
			cmds = append(cmds, sub)
		}
	}
	return cmds
}

func managementSubCommands(cmd *cobra.Command) []*cobra.Command {
	cmds := []*cobra.Command{}
	for _, sub := range cmd.Commands() {
		if sub.IsAvailableCommand() && sub.HasSubCommands() {
			cmds = append(cmds, sub)
		}
	}
	return cmds
}

var usageTemplate = `Usage:

{{- if not .HasSubCommands}}	{{.UseLine}}{{end}}
{{- if .HasSubCommands}}	{{ .CommandPath}} COMMAND{{end}}

{{ .Short | trim }}

{{- if gt .Aliases 0}}

Aliases:
  {{.NameAndAliases}}

{{- end}}
{{- if .HasExample}}

Examples:
{{ .Example }}

{{- end}}
{{- if .HasFlags}}

Options:
{{.Flags.FlagUsages | trimRightSpace}}

{{- end}}
{{- if hasManagementSubCommands . }}

Management Commands:

{{- range managementSubCommands . }}
  {{rpad .Name .NamePadding }} {{.Short}}
{{- end}}

{{- end}}
{{- if hasSubCommands .}}

Commands:

{{- range operationSubCommands . }}
  {{rpad .Name .NamePadding }} {{.Short}}
{{- end}}
{{- end}}

{{- if .HasSubCommands }}

Run '{{.CommandPath}} COMMAND --help' for more information on a command.
{{- end}}
`

var helpTemplate = `
{{if or .Runnable .HasSubCommands}}{{.UsageString}}{{end}}`