#!/bin/bash
#
# Copyright 2016-present the Material Components for iOS authors. All Rights Reserved.
#
# 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.

# Writes a patch to stdout that can be piped to git am. This is helpful for patching
# commits from one MDC repository to another where the base paths may not necessarily
# match.

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"; pushd $DIR >> /dev/null
MDC_ROOT="$(git rev-parse --show-toplevel | tail -n1)"; popd >> /dev/null
cd $MDC_ROOT

prefix=""
commit=""

usage() {
  echo "Usage: $0 -c [sha] -p [prefix]"
  echo
  echo "Example usage: $0 -c <sha> -p path/to/mdc"
}

while getopts "h?vc:p:" opt; do
  case "$opt" in
  h|\?)
      usage
      exit 0
      ;;
  v)  VERBOSE=1
      ;;
  c)  commit=$OPTARG
      ;;
  p)  prefix=$OPTARG
      ;;
  esac
done

if [[ -z "$prefix" || -z "$commit" ]]; then
  usage
  exit 0
fi

prefix="${prefix%/}/"
prefix="${prefix#$(pwd)/}"

git --no-pager \
  format-patch \
  -1 $commit \
  --stdout \
  --src-prefix=a/$prefix \
  --dst-prefix=b/$prefix