From 13f0c8c0f68ee8e25a9bb44dfdad819e1a7e5e2e Mon Sep 17 00:00:00 2001
From: Summer Mousa <smousa@zenoss.com>
Date: Wed, 16 Apr 2014 11:18:00 -0500
Subject: [PATCH] More consistent implementation of recursive subcommands

---
 app.go     | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 command.go | 39 ++++++++++++++++++++++++++++++++++++-
 help.go    | 46 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 140 insertions(+), 1 deletion(-)

diff --git a/app.go b/app.go
index a7c7122..f9342d7 100644
--- a/app.go
+++ b/app.go
@@ -129,6 +129,62 @@ func (a *App) Run(arguments []string) error {
 	return nil
 }
 
+// Invokes the subcommand given the context, parses ctx.Args() to generate command-specific flags
+func (a *App) RunAsSubcommand(c *Context) error {
+	// append help to commands
+	if a.Command(helpCommand.Name) == nil {
+		a.Commands = append(a.Commands, helpCommand)
+	}
+
+	// append help flags
+	if a.EnableBashCompletion {
+		a.appendFlag(BashCompletionFlag)
+	}
+	a.appendFlag(BoolFlag{"help, h", "show help"})
+
+	// parse flags
+	set := flagSet(a.Name, a.Flags)
+	set.SetOutput(ioutil.Discard)
+	err := set.Parse(c.Args().Tail())
+	nerr := normalizeFlags(a.Flags, set)
+	context := NewContext(a, set, set)
+
+	if nerr != nil {
+		fmt.Println(nerr)
+		ShowSubcommandHelp(context)
+		fmt.Println("")
+		return nerr
+	}
+
+	if err != nil {
+		fmt.Printf("Incorrect Usage.\n\n")
+		ShowSubcommandHelp(context)
+		fmt.Println("")
+		return err
+	}
+
+	if checkCompletions(context) {
+		return nil
+	}
+
+	if checkSubcommandHelp(context) {
+		return nil
+	}
+
+	args := context.Args()
+	if args.Present() {
+		name := args.First()
+		c := a.Command(name)
+		if c != nil {
+			return c.Run(context)
+		}
+	}
+
+	// Run default Action
+	a.Action(context)
+	return nil
+}
+
 // Returns the named command on App. Returns nil if the command does not exist
 func (a *App) Command(name string) *Command {
 	for _, c := range a.Commands {
diff --git a/command.go b/command.go
index 60d29aa..2d5c662 100644
--- a/command.go
+++ b/command.go
@@ -14,7 +14,7 @@ type Command struct {
 	ShortName string
 	// A short description of the usage of this command
 	Usage string
-	// A longer explaination of how the command works
+	// A longer explanation of how the command works
 	Description string
 	// The function to call when checking for bash command completions
 	BashComplete func(context *Context)
@@ -22,10 +22,16 @@ type Command struct {
 	Action func(context *Context)
 	// List of flags to parse
 	Flags []Flag
+	// List of child commands
+	Subcommands []Command
 }
 
 // Invokes the command given the context, parses ctx.Args() to generate command-specific flags
 func (c Command) Run(ctx *Context) error {
+	if len(c.Subcommands) > 0 {
+		return c.startApp(ctx)
+	}
+
 	// append help to flags
 	c.Flags = append(
 		c.Flags,
@@ -89,3 +95,34 @@ func (c Command) Run(ctx *Context) error {
 func (c Command) HasName(name string) bool {
 	return c.Name == name || c.ShortName == name
 }
+
+func (c Command) startApp(ctx *Context) error {
+	app := NewApp()
+
+	// set the name and usage
+	app.Name = fmt.Sprintf("%s %s", ctx.App.Name, c.Name)
+	if c.Description != "" {
+		app.Usage = c.Description
+	} else {
+		app.Usage = c.Usage
+	}
+
+	// set the flags and commands
+	app.Commands = c.Subcommands
+	app.Flags = c.Flags
+
+	// bash completion
+	app.EnableBashCompletion = ctx.App.EnableBashCompletion
+	if c.BashComplete != nil {
+		app.BashComplete = c.BashComplete
+	}
+
+	// set the action
+	if c.Action != nil {
+		app.Action = c.Action
+	} else {
+		app.Action = helpSubcommand.Action
+	}
+
+	return app.RunAsSubcommand(ctx)
+}
diff --git a/help.go b/help.go
index 64b4bab..db9ff02 100644
--- a/help.go
+++ b/help.go
@@ -44,6 +44,24 @@ OPTIONS:
    {{end}}
 `
 
+// The text template for the subcommand help topic.
+// cli.go uses text/template to render templates. You can
+// render custom help text by setting this variable.
+var SubcommandHelpTemplate = `NAME:
+   {{.Name}} - {{.Usage}}
+
+USAGE:
+   {{.Name}} [global options] command [command options] [arguments...]
+
+COMMANDS:
+   {{range .Commands}}{{.Name}}{{with .ShortName}}, {{.}}{{end}}{{ "\t" }}{{.Usage}}
+   {{end}}
+
+OPTIONS:
+   {{range .Flags}}{{.}}
+   {{end}}
+`
+
 var helpCommand = Command{
 	Name:      "help",
 	ShortName: "h",
@@ -58,6 +76,20 @@ var helpCommand = Command{
 	},
 }
 
+var helpSubcommand = Command{
+	Name:      "help",
+	ShortName: "h",
+	Usage:     "Shows a list of commands or help for one command",
+	Action: func(c *Context) {
+		args := c.Args()
+		if args.Present() {
+			ShowCommandHelp(c, args.First())
+		} else {
+			ShowSubcommandHelp(c)
+		}
+	},
+}
+
 // Prints help for the App
 var HelpPrinter = printHelp
 
@@ -87,6 +119,11 @@ func ShowCommandHelp(c *Context, command string) {
 	fmt.Printf("No help topic for '%v'\n", command)
 }
 
+// Prints help for the given subcommand
+func ShowSubcommandHelp(c *Context) {
+	HelpPrinter(SubcommandHelpTemplate, c.App)
+}
+
 // Prints the version number of the App
 func ShowVersion(c *Context) {
 	fmt.Printf("%v version %v\n", c.App.Name, c.App.Version)
@@ -145,6 +182,15 @@ func checkCommandHelp(c *Context, name string) bool {
 	return false
 }
 
+func checkSubcommandHelp(c *Context) bool {
+	if c.GlobalBool("h") || c.GlobalBool("help") {
+		ShowSubcommandHelp(c)
+		return true
+	}
+
+	return false
+}
+
 func checkCompletions(c *Context) bool {
 	if c.GlobalBool(BashCompletionFlag.Name) && c.App.EnableBashCompletion {
 		ShowCompletions(c)