#!/bin/sh
set -eu

core_root=${1:?usage: checkout-active-release.sh CORE_ROOT RELEASE_REF}
active_release_ref=${2:-}

if [ -z "$active_release_ref" ]; then
  exit 0
fi
case "$active_release_ref" in
  refs/sammo/*) ;;
  *)
    echo 'GATEWAY_ACTIVE_RELEASE_GIT_REF must be below refs/sammo/' >&2
    exit 64
    ;;
esac
if ! git check-ref-format "$active_release_ref" >/dev/null 2>&1; then
  echo 'GATEWAY_ACTIVE_RELEASE_GIT_REF is not a valid Git ref' >&2
  exit 64
fi
if ! git -C "$core_root" show-ref --verify --quiet "$active_release_ref"; then
  exit 0
fi
if ! git -C "$core_root" diff --quiet || ! git -C "$core_root" diff --cached --quiet; then
  echo 'Core bootstrap checkout has tracked changes; refusing to switch the active release ref' >&2
  exit 65
fi

active_release_sha=$(git -C "$core_root" rev-parse --verify "${active_release_ref}^{commit}")
git -C "$core_root" checkout --quiet --detach "$active_release_sha"
echo "Using persistent Gateway release $active_release_sha for runtime bootstrap."