help.go

// Copyright 2016 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"io"
	"os"
	"strings"
	"text/tabwriter"
	"text/template"

	"github.com/coreos/fleet/version"
	"github.com/spf13/cobra"
)

var (
	commandUsageTemplate *template.Template
	templFuncs           = template.FuncMap{
		"descToLines": func(s string) []string {
			// trim leading/trailing whitespace and split into slice of lines
			return strings.Split(strings.Trim(s, "\n\t "), "\n")
		},
		"cmdName": func(cCmd *cobra.Command, startCmd *cobra.Command) string {
			parts := []string{cCmd.Name()}
			for cCmd.HasParent() && cCmd.Parent().Name() != startCmd.Name() {
				cCmd = cCmd.Parent()
				parts = append([]string{cCmd.Name()}, parts...)
			}
			return strings.Join(parts, " ")
		},
	}
)

func init() {
	commandUsage := `
{{ $cmd := .Cmd }}\
{{ $cmdname := cmdName .Cmd .Cmd.Root }}\
NAME:
{{ if not .Cmd.HasParent }}\
{{printf "\t%s - %s" .Cmd.Name .Cmd.Short}}
{{else}}\
{{printf "\t%s - %s" $cmdname .Cmd.Short}}
{{end}}\

USAGE:
{{printf "\t%s" .Cmd.UseLine}}
{{ if not .Cmd.HasParent }}\

VERSION:
{{printf "\t%s" .Version}}
{{end}}\
{{if .Cmd.HasSubCommands}}\

COMMANDS:
{{range .SubCommands}}\
{{ $cmdname := cmdName . $cmd }}\
{{ if .Runnable }}\
{{printf "\t%s\t%s" $cmdname .Short}}
{{end}}\
{{end}}\
{{end}}\
{{ if .Cmd.Long }}\

DESCRIPTION:
{{range $line := descToLines .Cmd.Long}}{{printf "\t%s" $line}}
{{end}}\
{{end}}\
{{if .Cmd.HasLocalFlags}}\

OPTIONS:
{{.LocalFlags}}\
{{end}}\
{{if .Cmd.HasInheritedFlags}}\

GLOBAL OPTIONS:
{{.GlobalFlags}}\
{{end}}
`[1:]

	commandUsageTemplate = template.Must(template.New("command_usage").Funcs(templFuncs).Parse(strings.Replace(commandUsage, "\\\n", "", -1)))
}

func getSubCommands(cCmd *cobra.Command) []*cobra.Command {
	var subCommands []*cobra.Command
	for _, subCmd := range cCmd.Commands() {
		subCommands = append(subCommands, subCmd)
		subCommands = append(subCommands, getSubCommands(subCmd)...)
	}
	return subCommands
}

func usageFunc(cCmd *cobra.Command) error {
	subCommands := getSubCommands(cCmd)
	tabOut := getTabOutWithWriter(os.Stdout)
	commandUsageTemplate.Execute(tabOut, struct {
		Cmd         *cobra.Command
		LocalFlags  string
		GlobalFlags string
		SubCommands []*cobra.Command
		Version     string
	}{
		cCmd,
		cCmd.LocalFlags().FlagUsages(),
		cCmd.InheritedFlags().FlagUsages(),
		subCommands,
		version.Version,
	})
	tabOut.Flush()
	return nil
}

func getTabOutWithWriter(writer io.Writer) *tabwriter.Writer {
	aTabOut := new(tabwriter.Writer)
	aTabOut.Init(writer, 0, 8, 1, '\t', 0)

	return aTabOut
}