#!/bin/bash -e
# vim: set tabstop=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80:
#
# Copyright (c) 2017 Red Hat, Inc.
# Author: Nathaniel McCallum <npmccallum@redhat.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

SUMMARY="Decrypts using the policy defined at encryption time"

function findexe() {
    while read -d: path; do
        [ -f "$path/$1" -a -x "$path/$1" ] && echo "$path/$1" && return 0
    done <<< "$PATH:"
    return 1
}

if [ "$#" -eq 1 -a "$1" == "--summary" ]; then
    echo "$SUMMARY"
    exit 0
fi

if ! [ -t 0 ]; then
    read -d . hdr

    if ! pin=`jose fmt -q "$hdr" -SyOg clevis -Og pin -Su-`; then
        echo "JWE is missing the required 'clevis.pin' header property!" >&2
        exit 1
    fi

    if ! cmd="`findexe clevis-decrypt-$pin`"; then
        echo "Unable to locate pin '$pin'!" >&2
        exit 1
    fi

    exec "$cmd" < <(echo -n "$hdr."; cat)
fi

echo >&2
echo "Usage: clevis decrypt < JWE > PLAINTEXT" >&2
echo >&2
echo "$SUMMARY" >&2
echo >&2