git-legacy

#!/usr/bin/env bash

app_name="$(basename "${BASH_SOURCE[0]}")"
app_dir="$(dirname "${BASH_SOURCE[0]}")"

print_help() {
	expand -t 4 << EOF
Usage:
	$app_name <revision>
		Rebase the whole history of current HEAD on top of <revision>.

	$app_name
		Continue rebase loop after an interrupt.

Options:
	-?, --help
		Show this help information and exit.
EOF
}

args=()

while [[ $# -gt 0 ]]; do
	case "$1" in
		-\?|--help)
			print_help
			exit 0
			;;
		-*)
			echo "$app_name: [Error] Unknown option: $1" >&2
			exit 1
			;;
		*)
			args+=("$1")
			shift
			;;
	esac
done

set -- "${args[@]}"

git_dir="$(git rev-parse --git-dir)" || exit $?

interrupt () {
	echo "Interrupted."
	exit 1
}

trap interrupt INT

rebase_loop () {
	while [[ -d "$git_dir/rebase-merge" ]]; do
		git add . && git -c core.editor=true rebase --continue
	done
}

if [[ $# -eq 0 ]]; then
	rebase_loop
elif [[ $# -eq 1 ]]; then
	if ! "${app_dir}/git-is-worktree-clean" -q; then
		echo "$app_name: [Error] Working tree has changes." >&2 &&
		return 1
	fi
	history_tip="$1"
	git -c rebase.instructionFormat='%s%nexec git clean -fd; comm -13 -z <(git ls-tree --name-only -r %H -z | sort -z) <(git ls-files -z | sort -z) | xargs -0 rm -rf; git checkout --quiet %H -- . && git add . && GIT_AUTHOR_DATE="%ai" GIT_AUTHOR_NAME="%an" GIT_AUTHOR_EMAIL="%ae" GIT_COMMITTER_DATE="%ci" GIT_COMMITTER_NAME="%cn" GIT_COMMITTER_EMAIL="%ce" git commit --quiet --amend --no-edit' rebase -i --rebase-merges --update-refs "$history_tip"
	rebase_loop
else
	echo "$app_name: [Error] Invalid number of arguments ($#): Pass a git revision name to start rebase or nothing to continue automatic merge loop." >&2
fi