cmd/swarm: add implicit subcommand help (fix #786) (#788)

* cmd/swarm: add implicit subcommand help (fix #786)

* cmd/swarm: moved implicit help to a recursive func

cmd/swarm/main.go

@@ -190,6 +190,15 @@ var (
 	SWARM_ERR_SWAP_SET_NO_API = "SWAP is enabled but --swap-api is not set"
 )
 
+// this help command gets added to any subcommand that does not define it explicitly
+var defaultSubcommandHelp = cli.Command{
+	Action:             func(ctx *cli.Context) { cli.ShowCommandHelpAndExit(ctx, "", 1) },
+	CustomHelpTemplate: helpTemplate,
+	Name:               "help",
+	Usage:              "shows this help",
+	Hidden:             true,
+}
+
 var defaultNodeConfig = node.DefaultConfig
 
 // This init function sets defaults so cmd/swarm can run alongside geth.
@@ -377,6 +386,11 @@ pv(1) tool to get a progress bar:
 		// See config.go
 		DumpConfigCommand,
 	}
+
+	// append a hidden help subcommand to all commands that have subcommands
+	// if a help command was already defined above, that one will take precedence.
+	addDefaultHelpSubcommands(app.Commands)
+
 	sort.Sort(cli.CommandsByName(app.Commands))
 
 	app.Flags = []cli.Flag{
@@ -613,3 +627,16 @@ func injectBootnodes(srv *p2p.Server, nodes []string) {
 		srv.AddPeer(n)
 	}
 }
+
+// addDefaultHelpSubcommand scans through defined CLI commands and adds
+// a basic help subcommand to each
+// if a help command is already defined, it will take precedence over the default.
+func addDefaultHelpSubcommands(commands []cli.Command) {
+	for i := range commands {
+		cmd := &commands[i]
+		if cmd.Subcommands != nil {
+			cmd.Subcommands = append(cmd.Subcommands, defaultSubcommandHelp)
+			addDefaultHelpSubcommands(cmd.Subcommands)
+		}
+	}
+}