#!/bin/sh
#
# Part of Gerrit Code Review (https://www.gerritcodereview.com/)
#
# Copyright (C) 2009 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

set -u

# avoid [[ which is not POSIX sh.
if test "$#" != 1 ; then
  echo "$0 requires an argument."
  exit 1
fi

if test ! -f "$1" ; then
  echo "file does not exist: $1"
  exit 1
fi

if test ! -s "$1" ; then
  echo "file is empty: $1"
  exit 1
fi

if git rev-parse --verify HEAD >/dev/null 2>&1; then
  refhash="$(git rev-parse HEAD)"
else
  refhash="$(git hash-object -t tree /dev/null)"
fi

random=$({ git var "GIT_COMMITTER_IDENT" ; echo "$refhash" ; cat "$1"; } | git hash-object --stdin)
dest="$1.tmp.${random}"

# Avoid the --in-place option which only appeared in Git 2.8
# Avoid the --if-exists option which only appeared in Git 2.15
cat "$1" \
| git -c trailer.ifexists=doNothing interpret-trailers --trailer "Change-Id: I${random}" > "${dest}" \
&& mv "${dest}" "$1"