help.go

package main

import (
	"bytes"
	"fmt"
	"log"
	"sort"
	"strings"

	"github.com/mitchellh/cli"
)

// helpFunc is a cli.HelpFunc that can is used to output the help for Terraform.
func helpFunc(commands map[string]cli.CommandFactory) string {
	// Determine the maximum key length, and classify based on type
	porcelain := make(map[string]cli.CommandFactory)
	plumbing := make(map[string]cli.CommandFactory)
	maxKeyLen := 0
	for key, f := range commands {
		if len(key) > maxKeyLen {
			maxKeyLen = len(key)
		}

		if _, ok := PlumbingCommands[key]; ok {
			plumbing[key] = f
		} else {
			porcelain[key] = f
		}
	}

	var buf bytes.Buffer
	buf.WriteString("usage: terraform [--version] [--help] <command> [args]\n\n")
	buf.WriteString(
		"The available commands for execution are listed below.\n"  
			"The most common, useful commands are shown first, followed by\n"  
			"less common or more advanced commands. If you're just getting\n"  
			"started with Terraform, stick with the common commands. For the\n"  
			"other commands, please read the help and docs before usage.\n\n")
	buf.WriteString("Common commands:\n")
	buf.WriteString(listCommands(porcelain, maxKeyLen))
	buf.WriteString("\nAll other commands:\n")
	buf.WriteString(listCommands(plumbing, maxKeyLen))
	return buf.String()
}

// listCommands just lists the commands in the map with the
// given maximum key length.
func listCommands(commands map[string]cli.CommandFactory, maxKeyLen int) string {
	var buf bytes.Buffer

	// 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))
	for key, _ := range commands {
		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()
}