#!/bin/sh
set -eu

VERSION="${SYSGEN_VERSION:-0.1.3}"
BASE_URL="${SYSGEN_BASE_URL:-https://sysgen.sh}"

case "$(uname -m 2>/dev/null || true)" in
  x86_64|amd64) TARGET="x86_64-linux-musl" ;;
  *)
    echo "sysgen: unsupported architecture (v${VERSION} ships x86_64 only)" >&2
    exit 1
    ;;
esac

command -v bash >/dev/null 2>&1 || {
  echo "sysgen: bash is required" >&2
  exit 1
}
command -v tar >/dev/null 2>&1 || {
  echo "sysgen: tar is required" >&2
  exit 1
}

TMP="$(mktemp -d "${TMPDIR:-/tmp}/sysgen-install.XXXXXX")"
trap 'rm -rf "$TMP"' EXIT HUP INT TERM
ARTIFACT="sysgen-v${VERSION}-${TARGET}.tar.gz"
RELEASE_URL="${BASE_URL%/}/releases/v${VERSION}"

download() {
  url="$1"
  output="$2"
  if command -v curl >/dev/null 2>&1; then
    case "$url" in
      https://*) curl --proto '=https' --tlsv1.2 -fsSL "$url" -o "$output" ;;
      *) curl -fsSL "$url" -o "$output" ;;
    esac
  elif command -v wget >/dev/null 2>&1; then
    wget -qO "$output" "$url"
  else
    echo "sysgen: curl or wget is required" >&2
    exit 1
  fi
}

download "$RELEASE_URL/$ARTIFACT" "$TMP/$ARTIFACT"
download "$RELEASE_URL/SHA256SUMS" "$TMP/SHA256SUMS"

EXPECTED="$(awk -v file="$ARTIFACT" '$2 == file || $2 == "*" file { print $1; exit }' "$TMP/SHA256SUMS")"
[ -n "$EXPECTED" ] || {
  echo "sysgen: release checksum is missing" >&2
  exit 1
}
if command -v sha256sum >/dev/null 2>&1; then
  ACTUAL="$(sha256sum "$TMP/$ARTIFACT" | awk '{print $1}')"
elif command -v shasum >/dev/null 2>&1; then
  ACTUAL="$(shasum -a 256 "$TMP/$ARTIFACT" | awk '{print $1}')"
else
  echo "sysgen: sha256sum or shasum is required" >&2
  exit 1
fi
[ "$EXPECTED" = "$ACTUAL" ] || {
  echo "sysgen: release checksum mismatch" >&2
  exit 1
}

mkdir -p "$TMP/unpack"
tar -xzf "$TMP/$ARTIFACT" -C "$TMP/unpack"
PACKAGE="$TMP/unpack/sysgen-v${VERSION}-${TARGET}"
[ -x "$PACKAGE/boot.sh" ] && [ -x "$PACKAGE/sysgend" ] || {
  echo "sysgen: release package is incomplete" >&2
  exit 1
}

exec bash "$PACKAGE/boot.sh" --service "$@"