{ lib
, stdenv
, fetchurl
, fetchpatch
, ncurses
, pkg-config

  # `ps` with systemd support is able to properly report different
  # attributes like unit name, so we want to have it on linux.
, withSystemd ? stdenv.isLinux
, systemd

  # procps is mostly Linux-only. Most commands require a running Linux
  # system (or very similar like that found in Cygwin). The one
  # exception is ‘watch’ which is portable enough to run on pretty much
  # any UNIX-compatible system.
, watchOnly ? !(stdenv.isLinux || stdenv.isCygwin)
}:

stdenv.mkDerivation rec {
  pname = "procps";
  version = "3.3.16";

  # The project's releases are on SF, but git repo on gitlab.
  src = fetchurl {
    url = "mirror://sourceforge/procps-ng/procps-ng-${version}.tar.xz";
    sha256 = "1br0g93ysqhlv13i1k4lfbimsgxnpy5rgs4lxfc9rkzdbpbaqplj";
  };

  patches = [
    (fetchpatch {
      url = "https://gitlab.com/procps-ng/procps/-/commit/bb96fc42956c9ed926a1b958ab715f8b4a663dec.diff";
      sha256 = "0fzsb6ns3fvrszyzsz28qvbmcn135ilr4nwh2z1a0vlpl2fw961z";
      name = "sysconf-argmax-sanity.patch";
    })
  ];

  buildInputs = [ ncurses ]
    ++ lib.optional withSystemd systemd;
  nativeBuildInputs = [ pkg-config ];

  makeFlags = [ "usrbin_execdir=$(out)/bin" ]
    ++ lib.optionals watchOnly [ "watch" "PKG_LDFLAGS=" ];

  enableParallelBuilding = true;

  # Too red
  configureFlags = [ "--disable-modern-top" ]
    ++ lib.optional withSystemd "--with-systemd"
    ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
    "ac_cv_func_malloc_0_nonnull=yes"
    "ac_cv_func_realloc_0_nonnull=yes"
  ];

  installPhase = lib.optionalString watchOnly ''
    install -m 0755 -D watch $out/bin/watch
    install -m 0644 -D watch.1 $out/share/man/man1/watch.1
  '';

  meta = with lib; {
    homepage = "https://gitlab.com/procps-ng/procps";
    description = "Utilities that give information about processes using the /proc filesystem";
    priority = 11; # less than coreutils, which also provides "kill" and "uptime"
    license = licenses.gpl2;
    platforms = platforms.unix;
    maintainers = [ maintainers.typetetris ];
  };
}