#!/bin/sh
set -eu

usage() {
	cat <<-'EOF'
		Usage:
		  backup [-q] [-C COMMENT] [ARCHIVE_TAG]
		  backup -h
	EOF
}

help() {
	cat <<-'EOF'


		Options:
		  -q             disable verbose mode, useful for
		                 non-interactive sessions
		  -C COMMENT     the comment text to be attached to the archive
		  -h, --help     show this message

		  ARCHIVE_TAG    the tag used to create the new
		                 backup (default: "manual")


		The repository is expected to have been created with:

		  $ borg init -e repokey-blake2

		The following environment variables are expected to be exported:

		  $BORG_PASSCOMMAND
		  $BORG_REPO
		  $BORG_REMOTE_PATH

		Password-less SSH access is required, usually done via adding
		~/.ssh/id_rsa.pub to suyin:.ssh/authorized_keys.


		Examples:

		  Run backup manually:

		    $ backup

		  Create backup with comment, and verbose mode active:

		    $ backup -qC 'The backup has a comment' my-backup
	EOF
}

for flag in "$@"; do
	case "$flag" in
		--)
			break
			;;
		--help)
			usage
			help
			exit
			;;
		*)
			;;
	esac
done

VERBOSE_FLAGS='--verbose --progress'
COMMENT=''
while getopts 'qC:h' flag; do
	case "$flag" in
		q)
			VERBOSE_FLAGS=''
			;;
		C)
			COMMENT="$OPTARG"
			;;
		h)
			usage
			help
			exit
			;;
		*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))


ARCHIVE_TAG="${1:-manual}"


run() {
	set -x
	# The contents of $VERBOSE_FLAGS doesn't involve user input:
	# shellcheck disable=2086
	borg create \
		$VERBOSE_FLAGS                    \
		--comment "$COMMENT"              \
		--exclude "$XDG_CACHE_HOME"       \
		--exclude ~/Downloads/            \
		--stats                           \
		--compression lzma,9              \
		"::{hostname}-{now}-$ARCHIVE_TAG" \
		~/
	STATUS=$?
	set +x

	if [ "$STATUS" = 0 ]; then
		return 0
	elif [ "$STATUS" = 1 ]; then
		printf 'WARNING, but no ERROR.\n' >&2
		return 0
	else
		return "$STATUS"
	fi
}

run || exit $?