#!/bin/bash

pkgSrcDir="$1"
submoduleDir="$2"
url="$3"
path="${url%% *}"
url="${url#${path} }"

if [ -d "${path}" ] && [ -n "$(ls -A "${path}")" ]; then
  git -C "${pkgSrcDir}" submodule update 2>/dev/null || true
  exit
fi

if [ ! -f "${path}" ]; then
  >&2 echo 'update-submodule needs a commit'
  >&2 printf '"%s" ' "$@"
  >&2 printf '\n'
  exit 1
fi

commit=$(cat "${path}")
rm "${path}"
mkdir -p "${path}"
if [ -d "${submoduleDir}" ]; then
  upstream="${submoduleDir}/${path}"
  if [ ! -d "${upstream}" ]; then
    git clone -q "${url}" "${upstream}"
  fi
else
  upstream="${pkgSrcDir}/${path}"
fi
git -C "${upstream}" pull -q --ff-only
git -C "${upstream}" archive "${commit}" \
| tar -C "${path}" -x