# builder for Emacs packages built for packages.el
# using MELPA package-build.el

{
  lib,
  stdenv,
  fetchFromGitHub,
  emacs,
  texinfo,
  writeText,
  gcc,
}:

let
  genericBuild = import ./generic.nix {
    inherit
      lib
      stdenv
      emacs
      texinfo
      writeText
      gcc
      ;
  };

  packageBuild = stdenv.mkDerivation {
    name = "package-build";
    src = fetchFromGitHub {
      owner = "melpa";
      repo = "package-build";
      rev = "c48aa078c01b4f07b804270c4583a0a58ffea1c0";
      sha256 = "sha256-MzPj375upIiYXdQR+wWXv3A1zMqbSrZlH0taLuxx/1M=";
    };

    patches = [ ./package-build-dont-use-mtime.patch ];

    dontConfigure = true;
    dontBuild = true;

    installPhase = "
      mkdir -p $out
      cp -r * $out
    ";
  };

in

{
  /*
    pname: Nix package name without special symbols and without version or
    "emacs-" prefix.
  */
  pname,
  # ename: Original Emacs package name, possibly containing special symbols.
  ename ? null,
  version,
  recipe,
  meta ? { },
  ...
}@args:

genericBuild (
  {

    ename = if ename == null then pname else ename;

    elpa2nix = ./elpa2nix.el;
    melpa2nix = ./melpa2nix.el;

    inherit packageBuild;

    preUnpack = ''
      mkdir -p "$NIX_BUILD_TOP/recipes"
      if [ -n "$recipe" ]; then
        cp "$recipe" "$NIX_BUILD_TOP/recipes/$ename"
      fi

      ln -s "$packageBuild" "$NIX_BUILD_TOP/package-build"

      mkdir -p "$NIX_BUILD_TOP/packages"
    '';

    postUnpack = ''
      mkdir -p "$NIX_BUILD_TOP/working"
      ln -s "$NIX_BUILD_TOP/$sourceRoot" "$NIX_BUILD_TOP/working/$ename"
    '';

    buildPhase = ''
      runHook preBuild

      cd "$NIX_BUILD_TOP"

      emacs --batch -Q \
          -L "$NIX_BUILD_TOP/package-build" \
          -l "$melpa2nix" \
          -f melpa2nix-build-package \
          $ename $version $commit

      runHook postBuild
    '';

    installPhase = ''
      runHook preInstall

      archive="$NIX_BUILD_TOP/packages/$ename-$version.el"
      if [ ! -f "$archive" ]; then
          archive="$NIX_BUILD_TOP/packages/$ename-$version.tar"
      fi

      emacs --batch -Q \
          -l "$elpa2nix" \
          -f elpa2nix-install-package \
          "$archive" "$out/share/emacs/site-lisp/elpa"

      runHook postInstall
    '';

    meta = {
      homepage = args.src.meta.homepage or "https://melpa.org/#/${pname}";
    } // meta;
  }

  // removeAttrs args [ "meta" ]
)