#!/bin/sh
set -ef

certifi_uri="https://raw.githubusercontent.com/certifi/python-certifi/${CERTIFI_COMMIT:?}/certifi/cacert.pem"
dst_dir=/usr/local/share/ca-certificates

w=$(mktemp -d) ; : "${w:?}"
curl -sSL "${certifi_uri}" > "$w/cacert.pem"

def_bundle=/etc/ssl/certs/ca-certificates.crt

bundle_offsets() {
	grep -Fhne '-----END CERTIFICATE-----' "$1" | cut -d : -f 1 \
	| {
		s=1 ; while read -r e ; do
			[ -n "$e" ] || continue
			echo "$s,$e"
			s=$((e+1))
		done
	}
}

set +e
bundle_offsets "${def_bundle}" > "$w/offsets.0"
bundle_offsets "$w/cacert.pem" > "$w/offsets.1"
set -e

bundle_fingerprints() {
	while read -r a ; do
		[ -n "$a" ] || continue
		sed -ne "${a}p" "$1" | openssl x509 -noout -fingerprint
	done < "$2"
}

set +e
bundle_fingerprints "${def_bundle}" "$w/offsets.0" > "$w/fingerprints.0"
bundle_fingerprints "$w/cacert.pem" "$w/offsets.1" > "$w/fingerprints.1"
set -e

set +e
grep -Fxv -f "$w/fingerprints.0" "$w/fingerprints.1" > "$w/fingerprints.diff"
set -e

if [ -s "$w/fingerprints.diff" ] ; then
	set +e
	grep -Fxn -f "$w/fingerprints.diff" "$w/fingerprints.1" | cut -d : -f 1 > "$w/records.diff"
	set -e

	terse_fingerprint() {
		cut -d = -f 2- | tr '[:upper:]' '[:lower:]' | tr -cd '[:alnum:]'
	}

	mkdir "$w/extras"

	while read -r n ; do
		[ -n "$n" ] || continue
		fp=$(sed -ne "${n}p" "$w/fingerprints.1" | terse_fingerprint)
		off=$(sed -ne "${n}p" "$w/offsets.1")
		sed -ne "${off}p" "$w/cacert.pem" | openssl x509 > "${dst_dir}/certifi-${fp}.crt"
	done < "$w/records.diff"
fi

rm -rf "$w"

update-ca-certificates --fresh