{ stdenv, curl }:

{
  ipfs,
  url ? "",
  curlOpts ? "",
  outputHash ? "",
  outputHashAlgo ? "",
  md5 ? "",
  sha1 ? "",
  sha256 ? "",
  sha512 ? "",
  meta ? { },
  port ? "8080",
  postFetch ? "",
  preferLocalBuild ? true,
}:

let

  hasHash =
    (outputHash != "" && outputHashAlgo != "")
    || md5 != ""
    || sha1 != ""
    || sha256 != ""
    || sha512 != "";

in

if (!hasHash) then
  throw "Specify sha for fetchipfs fixed-output derivation"
else
  stdenv.mkDerivation {
    name = ipfs;
    builder = ./builder.sh;
    nativeBuildInputs = [ curl ];

    # New-style output content requirements.
    outputHashAlgo =
      if outputHashAlgo != "" then
        outputHashAlgo
      else if sha512 != "" then
        "sha512"
      else if sha256 != "" then
        "sha256"
      else if sha1 != "" then
        "sha1"
      else
        "md5";
    outputHash =
      if outputHash != "" then
        outputHash
      else if sha512 != "" then
        sha512
      else if sha256 != "" then
        sha256
      else if sha1 != "" then
        sha1
      else
        md5;

    outputHashMode = "recursive";

    inherit
      curlOpts
      postFetch
      ipfs
      url
      port
      meta
      ;

    # Doing the download on a remote machine just duplicates network
    # traffic, so don't do that.
    inherit preferLocalBuild;
  }