#!/bin/sh
# env
# Written in 2020 by Lucas
# CC0 1.0 Universal/Public domain - No rights reserved
#
# To the extent possible under law, the author(s) have dedicated all
# copyright and related and neighboring rights to this software to the
# public domain worldwide. This software is distributed without any
# warranty. You should have received a copy of the CC0 Public Domain
# Dedication along with this software. If not, see
# <http://creativecommons.org/publicdomain/zero/1.0/>.

usage()
{
	cat - <<EOF >&2
Usage:
	${0##*/} [-d digits] [-p period] [-a algorithm]
	${0##*/} [-H counter] [-d digits] [-a algorithm]
EOF
	exit 1
}

err()
{
	printf "%s: %s\n" "${0##*/}" "$*" >&2
	exit 1
}

algorithm=
counter=
digits=
period=
type=totp
while getopts a:d:H:p: flag; do
	case $flag in
	a)	algorithm=$OPTARG
		;;
	d)	digits=$OPTARG
		;;
	H)	counter=$OPTARG
		type=hotp
		;;
	p)	period=$OPTARG
		;;
	*)	usage
		;;
	esac
done

printf "otpauth://%s/" "$type"
printf "?secret="
cat - | tr -d "\n"
[ -n "$algorithm" ] && printf "&algorithm=%s" "$algorithm"
[ -n "$counter" ] && printf "&counter=%s" "$counter"
[ -n "$digits" ] && printf "&digits=%s" "$digits"
[ -n "$period" ] && printf "&period=%s" "$period"
printf "\n"