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

[[ $# -eq 4 ]] || {
  echo "usage: replace-native-recovery-beacon.sh <world-root> <candidate-image> <disk> <recovery-root>" >&2
  exit 64
}
[[ ${EUID} -eq 0 ]] || {
  echo "must run as root" >&2
  exit 77
}

world_root=$(readlink -f "$1")
candidate=$(readlink -f "$2")
disk=$(readlink -f "$3")
recovery_root=$(readlink -m "$4")
source_root=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
render_root=$(mktemp -d)
trap 'rm -rf "${render_root}"' EXIT

[[ ${disk} == /dev/vda ]]
[[ $(stat -c %s "${candidate}") -eq 14848 ]]
grep -q '^node_id: BS-SH-005$' "${world_root}/CURRENT.hldp"
/guanghu/bin/ghctl authorize "${world_root}" write_bootloader_and_system_partitions \
  >/dev/null

partition_dump=$(sfdisk -d "${disk}")
grep -q '^label: gpt$' <<<"${partition_dump}"
grep -Eq '^/dev/vda1 : start= *2048, size= *2048,' <<<"${partition_dump}"
grep -Eq '^/dev/vda2 : start= *4096, size= *104853471,' <<<"${partition_dump}"
grep -q '^GRUB_DEFAULT=guanghu-native-once$' /etc/default/grub
grep -q "menuentry 'Ubuntu'.*'gnulinux-simple-9842d3d6-a839-4127-bda7-f19137effe71'" \
  /boot/grub/grub.cfg

"${source_root}/scripts/render-native-recovery-beacon.sh" "${render_root}"
mkdir -p "${recovery_root}"
chmod 0700 "${recovery_root}"
printf '%s\n' "${partition_dump}" >"${recovery_root}/sfdisk-before.txt"
dd if="${disk}" of="${recovery_root}/first-2MiB.before.bin" \
  bs=1M count=2 status=none
dd if="${disk}" of="${recovery_root}/lba34-71.before.bin" \
  bs=512 skip=34 count=38 status=none
dd if="${disk}" of="${recovery_root}/lba70-71.before.bin" \
  bs=512 skip=70 count=2 status=none
if ! cmp -s "${recovery_root}/lba70-71.before.bin" \
  <(head -c 1024 /dev/zero); then
  if ! grep -aFq 'GHOS_GHCIP_INDEX_V1' \
    "${recovery_root}/lba70-71.before.bin" ||
    ! grep -aFq 'GHOS_GHCIP_ROOT_V1' \
      "${recovery_root}/lba70-71.before.bin"; then
    echo "native gestational index sectors 70-71 contain unknown data" >&2
    exit 65
  fi
fi
cp /boot/grub/grub.cfg "${recovery_root}/grub.cfg.before"
cp /boot/grub/grubenv "${recovery_root}/grubenv.before"
cp /etc/default/grub "${recovery_root}/default-grub.before"
tar -czf "${recovery_root}/etc-grub.d.before.tar.gz" -C /etc grub.d

dd if="${render_root}/guanghu-recovery-clear.env" of="${disk}" \
  bs=512 seek=68 count=2 conv=notrunc,fsync status=none
dd if="${candidate}" of="${disk}" \
  bs=512 seek=34 count=29 conv=notrunc,fsync status=none
install -m 0755 "${render_root}/08_guanghu_native_recovery" \
  /etc/grub.d/08_guanghu_native_recovery
install -D -m 0644 "${render_root}/guanghu-recovery-clear.env" \
  /usr/lib/guanghu-os/guanghu-recovery-clear.env
install -D -m 0755 "${source_root}/scripts/clear-native-recovery-beacon.sh" \
  /usr/local/sbin/guanghu-clear-native-recovery-beacon
install -m 0644 /dev/stdin \
  /etc/systemd/system/guanghu-native-recovery-beacon-clear.service <<'EOF'
[Unit]
Description=Verify and clear the Guanghu native recovery beacon
After=local-fs.target
Before=multi-user.target

[Service]
Type=oneshot
ExecStart=/usr/local/sbin/guanghu-clear-native-recovery-beacon /dev/vda /usr/lib/guanghu-os/guanghu-recovery-clear.env

[Install]
WantedBy=multi-user.target
EOF
systemctl enable guanghu-native-recovery-beacon-clear.service >/dev/null
update-grub >/dev/null
grub-script-check /boot/grub/grub.cfg

grep -q "load_env --file '(hd0)68+2' guanghu_recovery" /boot/grub/grub.cfg
grep -q 'set default="guanghu-native-once"' /boot/grub/grub.cfg
grep -q "menuentry 'Guanghu OS native one-time proof'.*'guanghu-native-once'" \
  /boot/grub/grub.cfg

candidate_sha=$(sha256sum "${candidate}" | awk '{print $1}')
candidate_readback_sha=$(dd if="${disk}" bs=512 skip=34 count=29 status=none |
  sha256sum | awk '{print $1}')
[[ ${candidate_sha} == "${candidate_readback_sha}" ]]
beacon_sha=$(sha256sum \
  "${render_root}/guanghu-recovery-clear.env" | awk '{print $1}')
beacon_readback_sha=$(dd if="${disk}" bs=512 skip=68 count=2 status=none |
  sha256sum | awk '{print $1}')
[[ ${beacon_sha} == "${beacon_readback_sha}" ]]

observed_at=$(date --iso-8601=seconds)
cat >"${recovery_root}/NATIVE-RECOVERY-BEACON-INSTALL-RECEIPT.hldp" <<EOF
schema: guanghu.native-recovery-beacon-install/v1
receipt_id: GH-OS-LAB-001-NATIVE-RECOVERY-BEACON-INSTALL-001
status: CONFIGURED_NOT_REBOOTED
observed_at: ${observed_at}
node_id: BS-SH-005
instance_id: lhins-14w5y3ce
candidate:
  lba_start: 34
  sector_count: 29
  sha256: ${candidate_sha}
  readback_sha256: ${candidate_readback_sha}
recovery_beacon:
  protocol: GHNRP
  lba_start: 68
  sector_count: 2
  clear_sha256: ${beacon_sha}
  readback_sha256: ${beacon_readback_sha}
grub:
  raw_blocklist: (hd0)68+2
  whitelisted_variable: guanghu_recovery
  native_default_preserved: true
  ubuntu_recovery_entry_preserved: true
hosted_fallback:
  clear_service_enabled: true
rollback:
  recovery_root: ${recovery_root}
  first_2mib_backed_up: true
  lba34_71_backed_up: true
  gestational_index_preserved_for_native_verification: true
  grub_configuration_backed_up: true
next_action: REBOOT_NATIVE_DEFAULT_THEN_PROVE_GHNRP_RECOVERS_UBUNTU
EOF
sha256sum "${recovery_root}"/* >"${recovery_root}/SHA256SUMS"
chmod 0400 "${recovery_root}"/*
sync
cat "${recovery_root}/NATIVE-RECOVERY-BEACON-INSTALL-RECEIPT.hldp"