xin/configs/emacs.nix

{
  runCommand,
  emacsWithPackagesFromUsePackage,
  pkgs,
  makeWrapper,
  writeTextDir,
  emacs,
  emacsPkg ? pkgs.emacs-gtk,
  ...
}:
let
  # Generate a .el file from our emacs.org.
  emacsConfig = runCommand "emacsConfig" { } ''
    mkdir -p $out
    cp -v ${./emacs.org} $out/emacs.org
    cd $out
    ${emacs}/bin/emacs --batch -Q -q \
                       --debug-init \
                       -l org emacs.org \
                       -f org-babel-tangle
    if [ $? != 0 ]; then
      echo "Generating failed!"
      exit 1;
    else
      echo "Generated org config!"
    fi
  '';

  # init.el to load my config and other dependencies.
  emacsInit = writeTextDir "share/emacs/site-lisp/init.el" ''
    (message "Loading my 'emacs.org' config from: ${emacsConfig}")
    (load "${emacsConfig}/emacs.el")
  '';
  emacsInitDir = "${emacsInit}/share/emacs/site-lisp";

  # Binaries that are needed in emacs
  emacsDepList = with pkgs; [
    go-font
    graphviz
    ispell
    texlive.combined.scheme-full
  ];
in
emacsWithPackagesFromUsePackage {
  config = ./emacs.org;

  alwaysEnsure = true;
  alwaysTangle = true;

  package = emacsPkg.overrideAttrs (
    oa: {
      nativeBuildInputs = oa.nativeBuildInputs ++ [
        makeWrapper
        emacsConfig
      ];
      postInstall = ''
        ${oa.postInstall}
        wrapProgram $out/bin/emacs \
          --prefix PATH : ${pkgs.lib.makeBinPath emacsDepList} \
          --add-flags '--init-directory ${emacsInitDir}'
      '';
    }
  );
}