if ! is-true "$(command git rev-parse --is-inside-work-tree 2> /dev/null)"; then
  print "${0}: not a repository work tree: ${PWD}" >&2
  return 1
elif [[ "${PWD}" != "$(git-root)" ]]; then
  print "${0}: must be run from the root of the work tree" >&2
  return 1
fi

local src="${1}"
local dst="${2}"
local url

url="$(command git config --file "$(git-root)/.gitmodules" --get "submodule.${src}.url")"

if [[ -z "${url}" ]]; then
  print "${0}: submodule not found: ${src}" >&2
  return 1
fi

mkdir -p "${dst:h}"

git-submodule-remove "${src}"
git submodule add "${url}" "${dst}"

return 0