#!/bin/bash

# Copyright (c) 2023 The Flatcar Maintainers.
# Use of this source code is governed by a BSD-style license that can
# be found in the LICENSE file.
#
# Script to generate sysext. See systemd-sysext(8). Prerequisite is
# that you've run build_packages and build_image.

SCRIPT_ROOT=$(dirname "$(readlink -f "$0")")
. "${SCRIPT_ROOT}/common.sh" || exit 1

# Script must run inside the chroot
assert_inside_chroot
assert_root_user

# All these are used to set up the 'BUILD_DIR' variable
DEFINE_string board "${DEFAULT_BOARD}" \
  "The board to build a sysext for."
DEFINE_string build_dir '' \
  "Directory used for building the sysext image, must exist, but should be empty."
DEFINE_string metapkgs '' \
  "Comma-separated list of meta-packages to build from source and install into sysext image."
DEFINE_string manglefs_script '' \
  "A path to executable that will customize the rootfs of the sysext image."
DEFINE_string squashfs_base '' \
  "The path to the squashfs base image."

FLAGS_HELP="USAGE: build_sysext [flags] [sysext name] [binary packages to install into image].

This script is used to build a Flatcar sysext image.

Examples:

Builds a sysext image named interpreters in the images
directory with dev-lang/python and dev-lang/perl packages for amd64:

sudo build_sysext \
     --board=amd64-usr \
     --build_dir=images \
     interpreters dev-lang/python dev-lang/perl

Builds a sysext image named oem-azure in the oem-images directory with
metapackage coreos-base/oem-azure for arm64:

sudo build_sysext \
     --board=arm64-usr \
     --build_dir=oem-images \
     --metapkgs=coreos-base/oem-azure \
     --mangle_fs=…/coreos-base/oem-azure/files/manglefs.sh \
     oem-azure

"

show_help_if_requested "$@"

# Parse command line
FLAGS "$@" || exit 1

eval set -- "${FLAGS_ARGV}"

source "${BUILD_LIBRARY_DIR}/board_options.sh" || exit 1
source "${BUILD_LIBRARY_DIR}/reports_util.sh" || exit 1

if [[ -z "${FLAGS_build_dir}" ]]; then
  die "Need a build directory to be specified with a --build_dir option"
fi

BUILD_DIR=$(realpath "${FLAGS_build_dir}")

# Architecture values are taken from systemd.unit(5).
declare -A SYSEXT_ARCHES
SYSEXT_ARCHES['amd64-usr']='x86-64'
SYSEXT_ARCHES['arm64-usr']='arm64'

declare -r SYSEXT_ARCHES

# Usage: _get_sysext_arch board [board...]
_get_sysext_arch() {
    local board=${1}
    if [[ ${#SYSEXT_ARCHES["${board}"]} -ne 0 ]]; then
        echo "${SYSEXT_ARCHES["${board}"]}"
    else
        die "Unknown board '${board}'"
    fi
}


set -euo pipefail

cleanup() {
  local dirs=(
    "${BUILD_DIR}/fs-root"
    "${BUILD_DIR}/install-root"
    "${BUILD_DIR}/workdir"
    "${BUILD_DIR}/img-rootfs"
  )
  umount "${dirs[@]}" 2>/dev/null || true
  rm -rf "${dirs[@]}" || true
}

if [[ ${#} -lt 1 ]]; then
   show_help_if_requested -h
  die 'Expected at least one parameter for sysext image name'
fi

SYSEXTNAME="${1}"
shift

# Set up trap to execute cleanup() on script exit
trap cleanup EXIT

ARCH=$(_get_sysext_arch "${FLAGS_board}")
if [[ -z "${FLAGS_squashfs_base}" ]]; then
  FLAGS_squashfs_base="${BUILD_DIR}/flatcar_production_image_sysext.squashfs"
fi
cleanup

mkdir "${BUILD_DIR}/fs-root"
mount -rt squashfs -o loop,nodev "${FLAGS_squashfs_base}" "${BUILD_DIR}/fs-root"
mkdir "${BUILD_DIR}/install-root"
mkdir "${BUILD_DIR}/workdir"
mount -t overlay overlay -o lowerdir="${BUILD_DIR}/fs-root",upperdir="${BUILD_DIR}/install-root",workdir="${BUILD_DIR}/workdir" "${BUILD_DIR}/install-root"
VERSION_BOARD=$(grep "^VERSION=" ${BUILD_DIR}/fs-root/usr/lib/os-release | cut -d = -f 2-)
if [ "$VERSION_BOARD" != "$FLATCAR_VERSION" ]; then
  echo "$VERSION_BOARD"
  echo "$FLATCAR_VERSION"
  echo "Version mismatch between board flatcar release and SDK container flatcar release"
  exit 1
fi

if [[ -n "${FLAGS_metapkgs}" ]]; then
  mapfile -t metapkgs < <(tr ',' '\n' <<<"${FLAGS_metapkgs}")
  "emerge-${FLAGS_board}" --nodeps --buildpkgonly --usepkg n --verbose "${metapkgs[@]}"
  set -- "${metapkgs[@]}" "${@}"
fi

for package; do
  echo "Installing package into sysext image: $package"
  FEATURES="-ebuild-locks" emerge \
    --root="${BUILD_DIR}/install-root" \
    --config-root="/build/${FLAGS_board}"  \
    --sysroot="/build/${FLAGS_board}"  \
    --root-deps=rdeps \
    --usepkgonly \
    --verbose \
    "${package}"
done

# Unmount in order to get rid of the overlay
umount "${BUILD_DIR}/install-root"
umount "${BUILD_DIR}/fs-root"

if [[ -n "${FLAGS_manglefs_script}" ]]; then
  if [[ ! -x "${FLAGS_manglefs_script}" ]]; then
    die "${FLAGS_manglefs_script} is not executable"
  fi
  "${FLAGS_manglefs_script}" "${BUILD_DIR}/install-root"
fi

info "Removing non-/usr directories from sysext image"
for entry in "${BUILD_DIR}/install-root"/*; do
  if [[ "${entry}" = */usr ]]; then
    continue
  fi
  info "  Removing ${entry##*/}"
  rm -rf "${entry}"
done
mkdir -p "${BUILD_DIR}/install-root/usr/lib/extension-release.d"
version_field="${VERSION_FIELD_OVERRIDE:-VERSION_ID=${FLATCAR_VERSION_ID}}"
all_fields=(
  'ID=flatcar'
  "${version_field}"
  "ARCHITECTURE=${ARCH}"
)
printf '%s\n' "${all_fields[@]}" >"${BUILD_DIR}/install-root/usr/lib/extension-release.d/extension-release.${SYSEXTNAME}"
mksquashfs "${BUILD_DIR}/install-root" "${BUILD_DIR}/${SYSEXTNAME}.raw"
rm -rf "${BUILD_DIR}"/{fs-root,install-root,workdir}

# Generate reports
mkdir "${BUILD_DIR}/img-rootfs"
mount -rt squashfs -o loop,nodev "${BUILD_DIR}/${SYSEXTNAME}.raw" "${BUILD_DIR}/img-rootfs"
write_contents "${BUILD_DIR}/img-rootfs" "${BUILD_DIR}/${SYSEXTNAME}_contents.txt"
write_contents_with_technical_details "${BUILD_DIR}/img-rootfs" "${BUILD_DIR}/${SYSEXTNAME}_contents_wtd.txt"
write_disk_space_usage_in_paths "${BUILD_DIR}/img-rootfs" "${BUILD_DIR}/${SYSEXTNAME}_disk_usage.txt"
umount "${BUILD_DIR}/img-rootfs"