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

set -Eeufo pipefail;
shopt -s lastpipe;

err()
{
	>&2 printf '%s\n' "$(basename "$0"): error: $*";
	exit 1;
}

git rev-parse --git-path bisect-rebase | read -r dir;

# Try the target first.
xargs git checkout --detach <"$dir/onto" 2>/dev/null;
if git-bisect-rebase--callback; then
	xargs git checkout <"$dir/head-name" >/dev/null 2>/dev/null;
	rm -rf "$dir";
	exit 0;
fi;

# Bisect.
xargs git bisect start <"$dir/git-bisect-options" >/dev/null;
xargs git bisect bad <"$dir/onto" >/dev/null;
cat "$dir/head-name" "$dir/onto" | xargs git merge-base | xargs git bisect good;
git bisect run git-bisect-rebase--callback;
git rev-parse bisect/bad >"$dir/bisect-bad";
git bisect reset >/dev/null 2>/dev/null;

# Perform the conflicting rebase
xargs git checkout <"$dir/head-name" >/dev/null 2>/dev/null;
cat "$dir/git-rebase-options" "$dir/bisect-bad" | xargs git rebase;
if test -e "$dir/post-exec"; then
	echo 'Running post-rebase exec.';
	bash "$dir/post-exec";
fi;