#!/bin/bash
# Copyright 2026, Alejandro Colomar <alx@kernel.org>
# SPDX-License-Identifier: GPL-3.0-or-later

set -Eeufo pipefail;
shopt -s lastpipe;

git rev-parse --git-dir | sed 's,$,/bisect-rebase,' | read -r dir;
# shellcheck disable=SC2064  # we want expansion now
trap "xargs git checkout --detach <'$dir/bisect-head' 2>/dev/null" EXIT;
git rev-parse HEAD >"$dir/bisect-head";

if test -e "$dir/pre-exec"; then
	printf '%s' 'Pre-rebase exec: ';
	if
		bash "$dir/pre-exec";
		x="$?";
		true;
	then
		echo "exit status: $x";
		if test "$x" -ne 0; then
			exit "$x";
		fi;
	fi;
fi;

xargs git checkout <"$dir/head-name" >/dev/null 2>/dev/null;
git rev-parse HEAD >"$dir/good-head";
printf '%s' 'Rebase: ';
cat "$dir/git-rebase-options" "$dir/bisect-head" \
| if xargs git rebase >/dev/null 2>/dev/null; then
	echo 'success';
else
	echo 'conflict';
	git rebase --abort >/dev/null;
	exit 1;
fi;

if test -e "$dir/post-exec"; then
	printf '%s' 'Post-rebase exec: ';
	if
		bash "$dir/post-exec";
		x="$?";
		true;
	then
		echo "exit status: $x";
		if test "$x" -ne 0; then
			xargs git reset --hard <"$dir/good-head";
			exit "$x";
		fi;
	fi;
fi;

{
	git rev-parse --abbrev-ref HEAD;
	git rev-parse HEAD;
} \
| sed '/^HEAD$/d' \
| sed '1!d' \
>"$dir/head-name";
exit 0;