Merge pull request #2906 from hashicorp/f-custom-help

Use a custom help output function

main.go

@@ -1,8 +1,12 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
+	"log"
 	"os"
+	"sort"
+	"strings"
 
 	"github.com/mitchellh/cli"
 	"github.com/sean-/seed"
@@ -44,7 +48,7 @@ func RunCustom(args []string, commands map[string]cli.CommandFactory) int {
 		Args:         args,
 		Commands:     commands,
 		Autocomplete: true,
-		HelpFunc:     cli.FilteredHelpFunc(commandsInclude, cli.BasicHelpFunc("nomad")),
+		HelpFunc:     cli.FilteredHelpFunc(commandsInclude, helpFunc),
 	}
 
 	exitCode, err := cli.Run()
@@ -55,3 +59,46 @@ func RunCustom(args []string, commands map[string]cli.CommandFactory) int {
 
 	return exitCode
 }
+
+// helpFunc is a custom help function. At the moment it is essentially a copy of
+// the cli.BasicHelpFunc that includes flags demonstrating how to use the
+// autocomplete flags.
+func helpFunc(commands map[string]cli.CommandFactory) string {
+	var buf bytes.Buffer
+	buf.WriteString("Usage: nomad [-version] [-help] [-autocomplete-(un)install] <command> [<args>]\n\n")
+	buf.WriteString("Available commands are:\n")
+
+	// Get the list of keys so we can sort them, and also get the maximum
+	// key length so they can be aligned properly.
+	keys := make([]string, 0, len(commands))
+	maxKeyLen := 0
+	for key := range commands {
+		if len(key) > maxKeyLen {
+			maxKeyLen = len(key)
+		}
+
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+
+	for _, key := range keys {
+		commandFunc, ok := commands[key]
+		if !ok {
+			// This should never happen since we JUST built the list of
+			// keys.
+			panic("command not found: " + key)
+		}
+
+		command, err := commandFunc()
+		if err != nil {
+			log.Printf("[ERR] cli: Command '%s' failed to load: %s",
+				key, err)
+			continue
+		}
+
+		key = fmt.Sprintf("%s%s", key, strings.Repeat(" ", maxKeyLen-len(key)))
+		buf.WriteString(fmt.Sprintf("    %s    %s\n", key, command.Synopsis()))
+	}
+
+	return buf.String()
+}