nixpkgs/pkgs/development/ruby-modules/with-packages/default.nix

{ stdenv, lib, buildEnv, buildRubyGem, ruby, gemConfig, makeBinaryWrapper }:

/*
Example usage:
nix-shell -E "(import <nixpkgs> {}).ruby.withPackages (pkgs: with pkgs; [ pry nokogiri ])"

You can also use this for writing ruby scripts that run anywhere that has nix
using a nix-shell shebang:
  #!/usr/bin/env nix-shell
  #!nix-shell -i ruby -p "ruby.withPackages (pkgs: with pkgs; [ pry nokogiri ])"


Run the following in the nixpkgs root directory to update the ruby-packages.nix:
./maintainers/scripts/update-ruby-packages
*/

let
  functions = import ../bundled-common/functions.nix { inherit lib gemConfig; };

  buildGems = gemset:
    let
      realGemset = if builtins.isAttrs gemset then gemset else import gemset;
      builtGems =
        lib.mapAttrs (name: initialAttrs:
          let
            attrs = functions.applyGemConfigs ({ inherit ruby; gemName = name; } // initialAttrs);
          in
            buildRubyGem (functions.composeGemAttrs ruby builtGems name attrs)
        ) realGemset;
    in builtGems;

  gems = buildGems (import ../../../top-level/ruby-packages.nix);

  withPackages = selector:
    let
      selected = selector gems;

      gemEnv = buildEnv {
        name = "ruby-gems";
        paths = selected;
        pathsToLink = [ "/lib" "/bin" "/nix-support" ];
      };

      wrappedRuby = stdenv.mkDerivation {
        name = "wrapped-${ruby.name}";
        nativeBuildInputs = [ makeBinaryWrapper ];
        buildCommand = ''
          mkdir -p $out/bin
          for i in ${ruby}/bin/*; do
            makeWrapper "$i" $out/bin/$(basename "$i") --set GEM_PATH ${gemEnv}/${ruby.gemPath}
          done
        '';
      };

    in stdenv.mkDerivation {
      name = "${ruby.name}-with-packages";
      nativeBuildInputs = [ makeBinaryWrapper ];
      buildInputs = [ selected ruby ];

      dontUnpack = true;

      installPhase = ''
        for i in ${ruby}/bin/* ${gemEnv}/bin/*; do
          rm -f $out/bin/$(basename "$i")
          makeWrapper "$i" $out/bin/$(basename "$i") --set GEM_PATH ${gemEnv}/${ruby.gemPath}
        done

        ln -s ${ruby}/nix-support $out/nix-support
      '';

      passthru = {
        inherit wrappedRuby;
        gems = selected;
      };
    };

in { inherit withPackages gems buildGems; }