#!/bin/sh
set -f

[ $# -gt 0 ] || exit 0
me=${0##*/}

[ -n "$1" ] || exit 1
[ -f "$1" ] || {
	env printf '%s: not a file or does not exist: %q\n' "${me}" "$1" >&2
	exit 1
}
[ -s "$1" ] || exit 0

w=$(mktemp -d) || exit 1
w_cleanup() {
	[ -z "$w" ] || ls -lA "$w/" >&2
	[ -z "$w" ] || rm -rf "$w"
	unset w
	exit "${1:-0}"
}

bundle_offsets() {
	awk '
	BEGIN { OFS = "," ; i_begin = 0 ; }
	$0 == "-----BEGIN CERTIFICATE-----" { i_begin = NR ; }
	$0 == "-----END CERTIFICATE-----"   { if (i_begin > 0) { print i_begin,NR ; i_begin = 0 ; } }
	' "$1"
}

bundle_fingerprints() {
	local x f
	while read -r x ; do
		[ -n "$x" ] || continue

		f=$(sed -ne "${x}p" "$1" | openssl x509 -noout -fingerprint -sha256)
		[ -n "$f" ] || f=$(sed -ne "${x}p" "$1" | openssl x509 -noout -fingerprint)
		[ -n "$f" ] || continue

		printf '%s\n' "$f" | tr '[:upper:]' '[:lower:]'
	done < "$2"
}

openssl storeutl -certs "$1" > "$w/cert.pem" || w_cleanup 1
[ -s "$w/cert.pem" ] || w_cleanup 1
tr -s '\r\n' '\n' < "$w/cert.pem" > "$w/cert.txt"
[ -s "$w/cert.txt" ] || w_cleanup 1
rm -f "$w/cert.pem"

bundle_offsets "$w/cert.txt" > "$w/cert.off"
[ -s "$w/cert.off" ] || w_cleanup 1

bundle_fingerprints "$w/cert.txt" "$w/cert.off" > "$w/cert.fp.all"
[ -s "$w/cert.fp.all" ] || w_cleanup 1

sort -uV < "$w/cert.fp.all" > "$w/cert.fp"
while read -r fp ; do
	[ -n "${fp}" ] || continue

	n=$(grep -m1 -Fxn -e "${fp}" "$w/cert.fp.all" | cut -d : -f 1)
	[ -n "$n" ] || continue

	off=$(sed -ne "${n}p" "$w/cert.off")
	[ -n "${off}" ] || continue

	sed -ne "${off}p" "$w/cert.txt"
done < "$w/cert.fp" > "$w/cert.pem"
[ -s "$w/cert.pem" ] || w_cleanup 1
rm -f "$w/cert.txt" "$w/cert.off" "$w/cert.fp.all"

if [ -n "$2" ] ; then
	while : ; do
		if [ -e "$2" ] ; then
			[ -f "$2" ] || break
		fi
		cat > "$2"
	break ; done
else
	cat
fi < "$w/cert.pem"

while [ -n "$3" ] ; do
	if [ -e "$3" ] ; then
		[ -f "$3" ] || break
	fi
	cat "$w/cert.fp" > "$3"
break ; done

while [ -n "$4" ] ; do
	if [ -e "$4" ] ; then
		[ -f "$4" ] || break
	fi
	bundle_offsets "$w/cert.pem" > "$4"
break ; done

rm -rf "$w" ; unset w