#!/usr/bin/env bash
# Creates the Firmware Update signing key pair, once (ADR 0003).
# The private key stays in ~/.config/roro9stack/ and must never be committed; the public key is
# written into the firmware source. Losing the private key means the next update goes over USB.
set -euo pipefail
ROOT="$(cd "$(dirname "$0")/.." && pwd)"
KEY="${RORO_OTA_KEY:-$HOME/.config/roro9stack/ota-key.pem}"
PUB_PEM="$ROOT/keys/ota-public.pem"
PUB_H="$ROOT/src/platform/ota_public_key.h"

if [ -e "$KEY" ]; then
    echo "A signing key already exists at $KEY; not overwriting it." >&2
    exit 1
fi
mkdir -p "$(dirname "$KEY")" "$ROOT/keys"
( umask 077; openssl ecparam -name prime256v1 -genkey -noout -out "$KEY" )
openssl ec -in "$KEY" -pubout -out "$PUB_PEM" 2>/dev/null

{
    echo "#pragma once"
    echo ""
    echo "// Public key that Firmware Updates must be signed for (ECDSA P-256). Generated by"
    echo "// scripts/ota_keygen.sh; the private key is not in this repository (ADR 0003)."
    echo "namespace roro {"
    echo "inline constexpr char kOtaPublicKeyPem[] ="
    sed 's/^/    "/; s/$/\\n"/' "$PUB_PEM"
    echo "    ;"
    echo "}  // namespace roro"
} > "$PUB_H"
echo "Private key: $KEY (keep it safe)"
echo "Public key:  $PUB_PEM and $PUB_H (commit these)"