#!/bin/sh
set -ef

export GIT_OPTIONAL_LOCKS=0

w=$(git rev-parse --path-format=absolute --show-toplevel) ; : "${w:?}" ; cd "$w"

dst='debian/patches/tmp-zen'
src='../linux-extras'
branches='bbr3 fixes zen-sauce'

if [ -d "${dst}" ] ; then rm -rf "${dst}" ; fi
mkdir -p "${dst}"

kver=
if [ -n "$1" ] ; then
	kver="$1"
else
	kver=$(dpkg-parsechangelog --show-field=Version | sed -E 's/^[0-9]+://;s/-[^-]*$//' | cut -d. -f1-2)
fi
from="upstream/linux-${kver}.y"

t=$(mktemp -d) ; : "${t:?}"

cp -ar "${src}" "$t/"
cd "$t/${src##*/}"

git config advice.skippedCherryPicks false

for b in ${branches} ; do
	ref="zen/${kver}/$b"
	r="tmp-rebase-$b"

	git switch --detach "${ref}"
	git switch -C "$r"

	rm -rf "$w/${dst}/$b" ; mkdir -p "$w/${dst}/$b"
	if git rebase "${from}" ; then
		git format-patch -N --subject-prefix='' --output-directory "$w/${dst}/$b" "${from}..$r"
	else
		echo >&2
		git rebase --abort

		touch "$w/${dst}/$b/0000-rebase-failed"

		base=$(git merge-base "${from}" "${ref}")
		git format-patch -N --subject-prefix='' --output-directory "$w/${dst}/$b" "${base}..${ref}"
	fi

	git switch -q --detach "${ref}"
	git branch -D "$r"
	echo >&2
done

cd "$w" ; rm -rf "$t"

echo >&2
echo 'output:' >&2
echo >&2
find "${dst}/" -type f -name '*.patch' | sed -E 's#^debian/patches/##' | sort -V