#!/usr/bin/env bash
set -euo pipefail

timestamp=$(date -u +"%Y%m%dT%H%M%SZ")
workdir="/tmp/backup-${timestamp}"
stagedir="${workdir}/backup-${timestamp}"
data_tar="${stagedir}/data.tar.zst"
db_path="${SQLITE_DB_PATH:-/var/lib/webui/app.db}"
remote_path="${BACKUP_REMOTE_PATH:-/remote}"
compression="${BACKUP_COMPRESSION:-zstd}"

mkdir -p "${stagedir}"

tar --xattrs --acls --numeric-owner -cpf - /data | zstd -19 -o "${data_tar}"

sqlite3 "${db_path}" ".backup '${stagedir}/app.db'"

data_size=$(stat -c %s "${stagedir}/data.tar.zst")
data_sha=$(sha256sum "${stagedir}/data.tar.zst" | awk '{print $1}')
db_size=$(stat -c %s "${stagedir}/app.db")
db_sha=$(sha256sum "${stagedir}/app.db" | awk '{print $1}')

cat > "${stagedir}/manifest.json" <<EOF
{
  "timestamp": "${timestamp}",
  "data_tar": "data.tar.zst",
  "database": "app.db",
  "sizes": {
    "data_tar": ${data_size},
    "database": ${db_size}
  },
  "sha256": {
    "data_tar": "${data_sha}",
    "database": "${db_sha}"
  }
}
EOF

cd "${workdir}"
xorriso -as mkisofs -o "${workdir}/backup-${timestamp}.iso" "backup-${timestamp}"

if [ "${compression}" = "gzip" ]; then
  gzip -9 "${workdir}/backup-${timestamp}.iso"
  archive="${workdir}/backup-${timestamp}.iso.gz"
else
  zstd -19 "${workdir}/backup-${timestamp}.iso"
  archive="${workdir}/backup-${timestamp}.iso.zst"
fi

mkdir -p "${remote_path}"
mv "${archive}" "${remote_path}/"

rm -rf "${workdir}"