#!/bin/sh
# msign PLAINMSG - generate a PGP/MIME signed message

[ -f "$1" ] || exit 1

if command -v gpg2 >/dev/null; then
	GPG=gpg2
else
	GPG=gpg
fi

IFS='
'

TMPD=$(mktemp -d -t msign.XXXXXX)
trap "rm -rf '$TMPD'" INT TERM EXIT

FROM=$(maddr -a -h from "$1" | sed 1q)
[ "$FROM" ] && key="--default-key=$FROM"

awk '/^$/,0' "$1" | mmime | sed 's/$/
/' >"$TMPD"/content
$GPG $key --armor --detach-sign -o "$TMPD"/signature.asc "$TMPD"/content ||
	exit $?

{
	sed '/^$/q' "$1"
	printf '#mblaze/raw %s/content\n' "$TMPD"
	printf '#application/pgp-signature %s/signature.asc\n' "$TMPD"
} |
	mmime -t 'multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"'