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 _, ok := HiddenCommands[key]; ok {
			// We don't consider hidden commands when deciding the
			// maximum command length.
			continue
		}

		if len(key) > maxKeyLen {
			maxKeyLen = len(key)
		}

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

	// The output produced by this is included in the docs at
	// website/source/docs/commands/index.html.markdown; if you
	// change this then consider updating that to match.
	helpText := fmt.Sprintf(`
Usage: terraform [global options] <subcommand> [args]

The available commands for execution are listed below.
The most common, useful commands are shown first, followed by
less common or more advanced commands. If you're just getting
started with Terraform, stick with the common commands. For the
other commands, please read the help and docs before usage.

Common commands:
%s
All other commands:
%s

Global options (use these before the subcommand, if any):
    -chdir=DIR         Switch to a different working directory before executing
                       the given subcommand.
    -help              Show this help output, or the help for a specified
                       subcommand.
    -version           An alias for the "version" subcommand.
`, listCommands(porcelain, maxKeyLen), listCommands(plumbing, maxKeyLen))

	return strings.TrimSpace(helpText)
}

// 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()
}