#!/usr/bin/env bash
#
# Retrieve migrations from the RPM and output an appropriately named tarball
set -eu -o pipefail

for opt in "$@"; do
   optarg="$(expr "${opt}" : '[^=]*=\(.*\)')"
   case "${opt}" in
      --package-dir=*) PACKAGE_DIR="${optarg}" ;;
      --output-dir=*) OUTPUT_DIR="${optarg}" ;;
   esac
done

# Store output artifacts in a versioned directory.
OUTPUT_DIR="${OUTPUT_DIR}/${VERSION_ID}-${BUILD_ID}"
mkdir -p "${OUTPUT_DIR}"

MIGRATIONS_ARCHIVE="bottlerocket-${VARIANT}-${ARCH}-${VERSION_ID}-${BUILD_ID}-migrations.tar"
MIGRATIONS_VERSIONED_SYMLINK="bottlerocket-${VARIANT}-${ARCH}-${VERSION_ID}-migrations.tar"
MIGRATIONS_FRIENDLY_VERSIONED_SYMLINK="bottlerocket-${VARIANT}-${ARCH}-v${VERSION_ID}-migrations.tar"
MIGRATIONS_SYMLINK="bottlerocket-${VARIANT}-${ARCH}-migrations.tar"
ROOT_TEMP="$(mktemp -d)"
SYS_ROOT="${ARCH}-bottlerocket-linux-gnu/sys-root"
MIGRATIONS_DIR="${ROOT_TEMP}/${SYS_ROOT}/usr/share/migrations"

# "Install" the migrations (just puts them in $MIGRATIONS_DIR)
rpm -iv --ignorearch --root "${ROOT_TEMP}" "${PACKAGE_DIR}"/*.rpm

if [ ! -d "${MIGRATIONS_DIR}" ]; then
  echo "Migrations directory does not exist: ${MIGRATIONS_DIR}"
  rm -rf "${ROOT_TEMP}"
  exit 1
fi

# lz4 compress each migration
for migration in "${MIGRATIONS_DIR}"/*; do
  [ -e "${migration}" ] || continue
  lz4 -v "${migration}" "${migration}.lz4"
done

# Tar up migrations with a .lz4 extension if they exist.
# Otherwise create an empty archive
pushd "${MIGRATIONS_DIR}"
if ls *.lz4 &> /dev/null; then
  tar -cvf "${OUTPUT_DIR}/${MIGRATIONS_ARCHIVE}" *.lz4
else
  tar -cvf "${OUTPUT_DIR}/${MIGRATIONS_ARCHIVE}" --files-from /dev/null
fi
popd

# Create friendly symlinks.
ln -s "${MIGRATIONS_ARCHIVE}" "${OUTPUT_DIR}/${MIGRATIONS_FRIENDLY_VERSIONED_SYMLINK}"
ln -s "${MIGRATIONS_ARCHIVE}" "${OUTPUT_DIR}/${MIGRATIONS_VERSIONED_SYMLINK}"
ln -s "${MIGRATIONS_ARCHIVE}" "${OUTPUT_DIR}/${MIGRATIONS_SYMLINK}"

rm -rf "${ROOT_TEMP}"