#!/usr/bin/env bash
#
# Given a file in a repo, create a series of git patches to import into
# another repo
#
# $1 == name of file (no leading path -- will be checked ./<file>)
#
# SPDX-License-Identifier: MIT

RSRC=$1
PDIR=/tmp/gitmrg

if [ ! -d "${PDIR}" ]; then
  echo "Creating ${PDIR} ..."
  mkdir -p "${PDIR}"
else
  echo "Cleaning ${PDIR} ..."
  rm -i "${PDIR}"/*
fi

if [ ! -f "./${RSRC}" ]; then
  echo "Bad input - must be in the git directory and name the file"
  exit 1
fi

_INIT=$(git rev-list --parents HEAD "${RSRC}" | grep -E "^[a-f0-9]{40}$")
git format-patch -1 -o "${PDIR}" --start-number 0 "${_INIT}" "${RSRC}"
git format-patch -o "${PDIR}" --start-number 1 "${_INIT}"..HEAD "${RSRC}"

echo "Next steps:"
echo " cd /destination/repo"
echo " git am ${PDIR}/*.patch"
echo " git push"

exit 0