{ lib
, stdenv
, fetchurl
, unzip
}:

let
  platforms = {
    aarch64-linux = { folder = "aarch64"; ld-linux = "ld-linux-aarch64.so.1"; };
    armv7l-linux = { folder = "armv7"; ld-linux = "ld-linux-armhf.so.3"; };
    i686-linux = { folder = "i686"; ld-linux = "ld-linux.so.2"; };
    x86_64-darwin = { folder = "."; };
    x86_64-linux = { folder = "amd64"; ld-linux = "ld-linux-x86-64.so.2"; };
  };
  platform = platforms."${stdenv.hostPlatform.system}"
    or (throw "Unsupported system: ${stdenv.hostPlatform.system}");
  download = if stdenv.isDarwin
    then { extension = "macos.zip"; hash = "sha256-MnL6lH7q/BrACG4fFJNfnvoh0JClVeaJIlX+XIj2aG4="; }
    else { extension = "linux.tar.gz"; hash = "sha256-rDi7pvDeKQM96GZTjDr6ZDQTGbaVu+OI77xf2egw6Sg="; };
in
stdenv.mkDerivation rec {
  pname = "pngout";
  version = "20200115";

  src = fetchurl {
    inherit (download) hash;
    url = "http://static.jonof.id.au/dl/kenutils/pngout-${version}-${download.extension}";
  };

  nativeBuildInputs = lib.optionals stdenv.isDarwin [ unzip ];

  # pngout is code-signed on Darwin, so don’t alter the binary to avoid breaking the signature.
  dontFixup = stdenv.isDarwin;

  installPhase = ''
    mkdir -p $out/bin
    cp ${platform.folder}/pngout $out/bin
  '' + lib.optionalString stdenv.isLinux ''
    patchelf --set-interpreter ${stdenv.cc.libc}/lib/${platform.ld-linux} $out/bin/pngout
  '';

  meta = {
    description = "A tool that aggressively optimizes the sizes of PNG images";
    license = lib.licenses.unfreeRedistributable;
    homepage = "http://advsys.net/ken/utils.htm";
    platforms = lib.attrNames platforms;
    maintainers = [ lib.maintainers.sander ];
  };
}