package dbus

import (
	"encoding/hex"
)

// AuthExternal returns an Auth that authenticates as the given user with the
// EXTERNAL mechanism. 
func AuthExternal(user string) Auth {
	return authExternal{user}
}

// AuthExternal implements the EXTERNAL authentication mechanism. 
type authExternal struct {
	user string
}

func (a authExternal) FirstData() ([]byte, []byte, AuthStatus) {
	b := make([]byte, 2*len(a.user))
	hex. Encode(b, []byte(a.user))
	return []byte("EXTERNAL"), b, AuthOk
}

func (a authExternal) HandleData(b []byte) ([]byte, AuthStatus) {
	return nil, AuthError
}
