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

[[ $# -ge 3 && $# -le 4 ]] || {
  echo "usage: build-guanghu-first-boot-initramfs.sh <output> <config> <grub-snapshot> [kernel-version]" >&2
  exit 64
}

output=$(readlink -m "$1")
config=$(readlink -f "$2")
grub_snapshot=$(readlink -f "$3")
kernel_version=${4:-$(uname -r)}
source_root=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
supervisor=${source_root}/scripts/guanghu-first-boot-supervisor.sh
packaging=${source_root}/packaging/initramfs-tools

command -v mkinitramfs >/dev/null
[[ -r /etc/initramfs-tools/initramfs.conf ]] || {
  echo "host initramfs configuration is unavailable" >&2
  exit 1
}
[[ -f ${config} && ! -L ${config} ]] || {
  echo "first-boot configuration is missing or unsafe" >&2
  exit 1
}
[[ -f ${grub_snapshot} && ! -L ${grub_snapshot} ]] || {
  echo "GRUB snapshot is missing or unsafe" >&2
  exit 1
}
grep -Fqx 'schema=guanghu.first-boot-supervisor/v1' "${config}"
grep -Fq 'gnulinux-simple-' "${grub_snapshot}"

build_root=$(mktemp -d)
trap 'rm -rf "${build_root}"' EXIT
mkdir -p "${build_root}/conf.d" "${build_root}/hooks" \
  "${build_root}/scripts/local-premount" \
  "$(dirname "${output}")"
install -m 0644 /etc/initramfs-tools/initramfs.conf "${build_root}/initramfs.conf"
install -m 0644 /dev/null "${build_root}/modules"
cp "${packaging}/hooks/guanghu-first-boot-supervisor" "${build_root}/hooks/"
cp "${packaging}/scripts/local-premount/guanghu-first-boot-supervisor" \
  "${build_root}/scripts/local-premount/"
chmod 0755 "${build_root}/hooks/guanghu-first-boot-supervisor" \
  "${build_root}/scripts/local-premount/guanghu-first-boot-supervisor"

export GUANGHU_FIRST_BOOT_SUPERVISOR_SOURCE=${supervisor}
export GUANGHU_FIRST_BOOT_CONFIG_SOURCE=${config}
export GUANGHU_FIRST_BOOT_GRUB_SOURCE=${grub_snapshot}
mkinitramfs -d "${build_root}" -o "${output}" "${kernel_version}"
chmod 0600 "${output}"
sha256sum "${output}" >"${output}.sha256"
printf 'GUANGHU_FIRST_BOOT_INITRAMFS_BUILT kernel=%s output=%s\n' \
  "${kernel_version}" "${output}"