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

[[ $# -eq 1 ]] || {
  echo "usage: render-native-recovery-beacon.sh <output-directory>" >&2
  exit 64
}

mkdir -p "$1"
output_root=$(cd "$1" && pwd)

python3 - "${output_root}" <<'PY'
import pathlib
import sys

output = pathlib.Path(sys.argv[1])
header = (
    b"# GRUB Environment Block\n"
    b"# WARNING: Do not edit this file by tools other than grub-editenv!!!\n"
)

def write_environment(name: str, variables: bytes = b"") -> None:
    prefix = header + variables
    if len(prefix) > 1024:
        raise SystemExit(f"{name} exceeds the GRUB environment-block size")
    (output / name).write_bytes(prefix + b"#" * (1024 - len(prefix)))

write_environment(
    "guanghu-recovery-active.env",
    b"guanghu_recovery=ubuntu\n",
)
write_environment("guanghu-recovery-clear.env")
PY

install -m 0755 /dev/stdin "${output_root}/08_guanghu_native_recovery" <<'EOF'
#!/bin/sh
exec tail -n +3 $0
insmod loadenv
set guanghu_recovery=
if load_env --file '(hd0)68+2' guanghu_recovery; then
    if [ "${guanghu_recovery}" = "ubuntu" ]; then
        set default="gnulinux-simple-9842d3d6-a839-4127-bda7-f19137effe71"
    fi
fi
EOF

sha256sum \
  "${output_root}/guanghu-recovery-active.env" \
  "${output_root}/guanghu-recovery-clear.env" \
  "${output_root}/08_guanghu_native_recovery" \
  >"${output_root}/SHA256SUMS"