package main

import (
	"bufio"
	"crypto/openpgp"
	"crypto/openpgp/armor"
	"flag"
	"io"
	"log"
	"os"
)

var dearmor = flag.Bool("d", false, "dearmor binary key")
var publiconly = flag.Bool("p", false, "ouput public part only, even if input is a private key")

func serialize(w io.Writer, e *openpgp.Entity, publiconly bool) (err error) {
	if publiconly {
		err = e.Serialize(w)
	} else {
		err = e.SerializePrivate(w)
	}
	return
}

func code(e *openpgp.Entity, arm bool) (err error) {
	pub := e.PrivateKey == nil || *publiconly
	header := openpgp.PublicKeyType
	if !pub {
		header = openpgp.PrivateKeyType
	}
	out := bufio.NewWriter(os.Stdout)
	if arm {
		w, err1 := armor.Encode(out, header, nil)
		err = err1
		if err != nil {
			return
		}
		err = serialize(w, e, pub)
		if err != nil {
			return
		}
		err = w.Close()
		if err != nil {
			return
		}
		_, err = out.Write([]byte{'\n'})
		if err != nil {
			return
		}
	} else {
		err = serialize(out, e, pub)
		if err != nil {
			return
		}
	}
	err = out.Flush()
	return
}

func main() {
	flag.Parse()
	var elist openpgp.EntityList
	var err error
	in := bufio.NewReader(os.Stdin)
	if *dearmor {
		elist, err = openpgp.ReadArmoredKeyRing(in)
	} else {
		elist, err = openpgp.ReadKeyRing(in)
	}
	if err != nil {
		log.Fatal(err)
	}
	if len(elist) != 1 {
		log.Fatal("expected a single key")
	}
	err = code(elist[0], !*dearmor)
	if err != nil {
		log.Fatal(err)
	}
	return
}