{ lib
, runCommandLocal
, gfal2-util
}:

# `url` and `urls` should only be overriden via `<pkg>.override`, but not `<pkg>.overrideAttrs`.
{ name ? ""
, pname ? ""
, version ? ""
, urls ? [ ]
, url ? if urls == [ ] then abort "Expect either non-empty `urls` or `url`" else lib.head urls
, hash ? lib.fakeHash
, recursive ? false
, intermediateDestUrls ? [ ]
, extraGfalCopyFlags ? [ ]
, allowSubstitutes ? true
}:

(runCommandLocal name { } ''
  for u in "''${urls[@]}"; do
    gfal-copy "''${gfalCopyFlags[@]}" "$u" "''${intermediateDestUrls[@]}" "$out"
    ret="$?"
    (( ret )) && break
  done
  if (( ret )); then
    echo "gfal-copy failed trying to download from any of the urls" >&2
    exit "$ret"
  fi
'').overrideAttrs (finalAttrs: previousAttrs:
{
  __structuredAttrs = true;
  inherit allowSubstitutes;
  nativeBuildInputs = [ gfal2-util ];
  outputHashAlgo = null;
  outputHashMode = if finalAttrs.recursive then "recursive" else "flat";
  outputHash = hash;
  inherit url;
  urls = if urls == [ ] then lib.singleton url else urls;
  gfalCopyFlags = extraGfalCopyFlags
  ++ lib.optional finalAttrs.recursive "--recursive"
  ;
  inherit recursive intermediateDestUrls;
} // (if (pname != "" && version != "") then {
  inherit pname version;
  name = "${finalAttrs.pname}-${finalAttrs.version}";
} else {
  name = if (name != "") then name else (baseNameOf url);
}))