sparrow/vendor/github.com/kataras/survey/password.go

package survey

import (
	"os"

	"github.com/kataras/survey/core"
	"github.com/kataras/survey/terminal"
)

/*
Password is like a normal Input but the text shows up as *'s and there is no default. Response
type is a string.

	password := ""
	prompt := &survey.Password{ Message: "Please type your password" }
	survey.AskOne(prompt, &password, nil)
*/
type Password struct {
	core.Renderer
	Message string
	Help    string
}

type PasswordTemplateData struct {
	Password
	ShowHelp bool
}

// Templates with Color formatting. See Documentation: https://github.com/mgutz/ansi#style-format
var PasswordQuestionTemplate = `
{{- if .ShowHelp }}{{- color "cyan"}}{{ HelpIcon }} {{ .Help }}{{color "reset"}}{{"\n"}}{{end}}
{{- color "green+hb"}}{{ QuestionIcon }} {{color "reset"}}
{{- color "default+hb"}}{{ .Message }} {{color "reset"}}
{{- if and .Help (not .ShowHelp)}}{{color "cyan"}}[{{ HelpInputRune }} for help]{{color "reset"}} {{end}}`

func (p *Password) Prompt() (line interface{}, err error) {
	// render the question template
	out, err := core.RunTemplate(
		PasswordQuestionTemplate,
		PasswordTemplateData{Password: *p},
	)
	terminal.Print(out)
	if err != nil {
		return "", err
	}

	rr := terminal.NewRuneReader(os.Stdin)
	rr.SetTermMode()
	defer rr.RestoreTermMode()

	// no help msg?  Just return any response
	if p.Help == "" {
		line, err := rr.ReadLine('*')
		return string(line), err
	}

	// process answers looking for help prompt answer
	for {
		line, err := rr.ReadLine('*')
		if err != nil {
			return string(line), err
		}

		if string(line) == string(core.HelpInputRune) {
			// terminal will echo the \n so we need to jump back up one row
			terminal.CursorPreviousLine(1)

			err = p.Render(
				PasswordQuestionTemplate,
				PasswordTemplateData{Password: *p, ShowHelp: true},
			)
			if err != nil {
				return "", err
			}
			continue
		}
		return string(line), err
	}
}

// Cleanup hides the string with a fixed number of characters.
func (prompt *Password) Cleanup(val interface{}) error {
	return nil
}