cli/mtool/main.go

package mtool

// The package implements fast way
// to make multitool CLI applications.

import (
	"flag"
	"os"
	"time"
)


type Flags struct {
	*flag.FlagSet
	tool *Tool
	args []string
	parsedArgs []string
	envNameMap map[string] []string
	envMap map[string]string
}

type ToolMap map[string] *Tool

func (flags *Flags) wasPassed(name string) bool {
	found := false
	flags.Visit(func(f *flag.Flag){
		if f.Name == name {
			found = true
		}
	})
	return found
}

func (flags *Flags) setEnv(
	name string,
	env []string,
) bool {
	flags.envNameMap[name] = env
	for _, k := range env {
		value, has := os.LookupEnv(k)
		if !has {
			continue
		}

		flags.envMap[name] = value
		return true
	}

	return false
}

// Set new string variable
// to parse.
func (flags *Flags) StringVar(
	p *string,
	name string,
	value string,
	usage string,
	env ...string,
) {
	flags.FlagSet.StringVar(p, name, value, usage)
	flags.setEnv(name, env)
}

// Set new int variable to parse.
func (flags *Flags) IntVar(
	p *int,
	name string,
	value int,
	usage string,
	env ...string,
) {
	flags.FlagSet.IntVar(p, name, value, usage)
	flags.setEnv(name, env)
}

// Set new int64 variable to parse.
func (flags *Flags) Int64Var(
	p *int64,
	name string,
	value int64,
	usage string,
	env ...string,
) {
	flags.FlagSet.Int64Var(p, name, value, usage)
	flags.setEnv(name, env)
}

// Set new bool variable to parse.
func (flags *Flags) BoolVar(
	p *bool,
	name string,
	value bool,
	usage string,
	env ...string,
) {
	flags.FlagSet.BoolVar(p, name, value, usage)
	flags.setEnv(name, env)
}

// Set new float64 variable to parse.
func (flags *Flags) Float64Var(
	p *float64,
	name string,
	value float64,
	usage string,
	env ...string,
) {
	flags.FlagSet.Float64Var(p, name, value, usage)
	flags.setEnv(name, env)
}

// Set new duration variable to parse.
func (flags *Flags) DurationVar(
	p *time.Duration,
	name string,
	value time.Duration,
	usage string,
	env ...string,
) {
	flags.FlagSet.DurationVar(p, name, value, usage)
	flags.setEnv(name, env)
}

func (flags *Flags) Parse() []string {

	flags.FlagSet.Parse(flags.args)
	for name, v := range flags.envMap {
		if !flags.wasPassed(name) {
			flags.FlagSet.Set(name, v)
		}
	}

	flags.parsedArgs = flags.FlagSet.Args()
	return flags.parsedArgs
}

// Get all the arguments, including the
// parsed ones.
func (flags *Flags) AllArgs() []string {
	return flags.args
}

// Get all the arguments going after options.
func (flags *Flags) Args() []string {
	return flags.parsedArgs
}

// Get the tool currently called.
func (flags *Flags) Tool() *Tool {
	return flags.tool
}