{ stdenv, fetchFromGitHub, emacs }:

let version = "0.2";

in stdenv.mkDerivation {
  name = "spacemacs-funcs-${version}";

  srcs = [
    (fetchFromGitHub {
      owner = "syl20bnr";
      repo = "spacemacs";
      rev = "200.9";
      sha256 = "81e8fc56421e00405cba2d78f8b5e14b1d9e8e23803dcf43eb8e89b72273ea1b";
     })
    (fetchFromGitHub {
      owner = "WhittlesJr";
      repo = "spacemacs-functions";
      rev = "0.2";
      sha256 = "e653e96a7aea92762841bc5eed968ce514e2e4e8ee1a919abb85e427f04bd27c";
     })
  ];

  buildInputs = [ emacs ];

  # The following is ported from https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=emacs-spacemacs-funcs.
  buildPhase = ''
    emacs -q --no-splash -batch -L . -f batch-byte-compile spacemacs-funcs.el

    cd "spacemacs-$version"
    shopt -s globstar
    shopt -s extglob
    emacs -q --no-splash -batch -L . -f batch-byte-compile {core,layers}/**/*funcs*.el
  '';

  installPhase = ''
    dest="$out/share/emacs/site-lisp"

    install -d $dest

    install -m644 spacemacs-funcs.el{c,} $dest

    cd "spacemacs-$version"
    shopt -s globstar
    shopt -s extglob
    find {core,layers}/ -name *funcs.el* -exec bash -c 'file=${1#./}; install -m644 "$file" "$dest${file//\//_}"' _ '{}' \;
  '';

  meta = {
    description = "Useful functions from the Spacemacs project";
    homepage = https://github.com/WhittlesJr/spacemacs-functions;
    license = stdenv.lib.licenses.gpl3;
    platforms = stdenv.lib.platforms.all;
  };
}