MV3DT_APP_SUBDIR="src/apps/reference_apps/deepstream-tracker-3d-multi-view"

is_mv3dt_app_dir() {
  test -f "$1/README.md" || return 1
  test -d "$1/config_templates" || return 1
  test -d "$1/scripts" || return 1
  grep -q "Multi-View 3D Tracking" "$1/README.md"
}

GIT_TOP="$(git rev-parse --show-toplevel 2>/dev/null || true)"
CANDIDATES=()
if [ -n "${MV3DT_REPO_ROOT:-}" ]; then CANDIDATES+=("${MV3DT_REPO_ROOT}"); fi
if [ -n "${DEEPSTREAM_REPO_ROOT:-}" ]; then CANDIDATES+=("${DEEPSTREAM_REPO_ROOT}/${MV3DT_APP_SUBDIR}"); fi
CANDIDATES+=("${PWD}")
if [ -n "${GIT_TOP}" ]; then
  CANDIDATES+=("${GIT_TOP}" "${GIT_TOP}/${MV3DT_APP_SUBDIR}")
fi
CANDIDATES+=("${HOME}/DeepStream/${MV3DT_APP_SUBDIR}" "${HOME}/deepstream/${MV3DT_APP_SUBDIR}")

REPO_ROOT=""
for candidate in "${CANDIDATES[@]}"; do
  if [ -n "$candidate" ] && is_mv3dt_app_dir "$candidate"; then
    REPO_ROOT="$(cd "$candidate" && pwd)"
    break
  fi
done

if [ -z "${REPO_ROOT}" ]; then
  cat <<'EOF'
ERROR: MV3DT reference app directory was not found.
Set MV3DT_REPO_ROOT to an existing deepstream-tracker-3d-multi-view app directory, or ask the user to approve cloning the public DeepStream repo and then run:

  DEEPSTREAM_REPO_ROOT="${DEEPSTREAM_REPO_ROOT:-$HOME/DeepStream}"
  git clone https://github.com/NVIDIA/DeepStream.git "$DEEPSTREAM_REPO_ROOT"
  export MV3DT_REPO_ROOT="$DEEPSTREAM_REPO_ROOT/src/apps/reference_apps/deepstream-tracker-3d-multi-view"

Do not clone silently.
EOF
  exit 1
fi

cd "${REPO_ROOT}"
export REPO_ROOT MV3DT_REPO_ROOT="${REPO_ROOT}"