#!/usr/bin/env bash

# A script to perform incremental backups with rsync
# Source: https://linuxconfig.org/how-to-create-incremental-backups-using-rsync-on-linux

set -o errexit
set -o nounset
set -o pipefail

readonly BACKUP_DIR="/mnt/backup"
readonly DATETIME
DATETIME="$(date '+%Y-%m-%d_%H:%M:%S')"
readonly BACKUP_PATH="${BACKUP_DIR}/${DATETIME}"
readonly LATEST_LINK="${BACKUP_DIR}/latest"
readonly TEMP_DIR
TEMP_DIR=$(mktemp -d || echo "Failed to make temp dir"; exit 1)
chmod 700 "${TEMP_DIR}"
trap 'rm -rf "${TEMP_DIR}"; exit 0' 0 1 2 3 15

mkdir -p "${BACKUP_DIR}"

while read -r line; do
    rsync -aAX "$line" "${TEMP_DIR}";
done </etc/rsync-includes.txt

rsync -av --delete "${TEMP_DIR}/" --link-dest "${LATEST_LINK}" --exclude=".cache" "${BACKUP_PATH}"

rm -rf "${LATEST_LINK}"
ln -s "${BACKUP_PATH}" "${LATEST_LINK}"