{ pkgs, stdenv, lib, bundler, fetchurl, fetchFromGitHub, bundlerEnv, libiconv
, ruby, tzdata, git, nodejs, procps, dpkg, yarn
}:

/* When updating the Gemfile add `gem "activerecord-nulldb-adapter"`
   to allow building the assets without a database */

let
  # Taken from yarn2nix
  buildYarnPackageDeps = {
    name,
    packageJson,
    yarnLock,
    yarnNix,
    pkgConfig ? {},
    yarnFlags ? []
  }:
    let
      offlineCache = (pkgs.callPackage yarnNix {}).offline_cache;
      extraBuildInputs = (lib.flatten (builtins.map (key:
        pkgConfig.${key} . buildInputs or []
      ) (builtins.attrNames pkgConfig)));
      postInstall = (builtins.map (key:
        if (pkgConfig.${key} ? postInstall) then
          ''
            for f in $(find -L -path '*/node_modules/${key}' -type d); do
              (cd "$f" && (${pkgConfig.${key}.postInstall}))
            done
          ''
        else
          ""
      ) (builtins.attrNames pkgConfig));
    in
    stdenv.mkDerivation {
      name = "${name}-modules";

      phases = ["buildPhase"];
      buildInputs = [ yarn nodejs ] ++ extraBuildInputs;

      buildPhase = ''
        # Yarn writes cache directories etc to $HOME.
        export HOME=`pwd`/yarn_home
        cp ${packageJson} ./package.json
        cp ${yarnLock} ./yarn.lock
        chmod +w ./yarn.lock
        yarn config --offline set yarn-offline-mirror ${offlineCache}
        # Do not look up in the registry, but in the offline cache.
        # TODO: Ask upstream to fix this mess.
        sed -i -E 's|^(\s*resolved\s*")https?://.*/|\1|' yarn.lock
        yarn install ${lib.escapeShellArgs yarnFlags}
        ${lib.concatStringsSep "\n" postInstall}
        mkdir $out
        mv node_modules $out/
        patchShebangs $out
      '';
    };
  node-env = buildYarnPackageDeps {
    name = "gitlab";
    packageJson = ./package.json;
    yarnLock = ./yarn.lock;
    yarnNix = ./yarn.nix;
    yarnFlags = [
      "--offline"
      "--frozen-lockfile"
      "--ignore-engines"
      "--ignore-scripts"
    ];
    # pkgConfig might need to come from node-packages ?
  };
  ruby-env = bundlerEnv {
    name = "gitlab-env-0.2";
    inherit ruby;
    gemdir = ./.;
    meta = with lib; {
      homepage = http://www.gitlab.com/;
      platforms = platforms.linux;
      maintainers = with maintainers; [ fpletz globin ];
      license = licenses.mit;
    };
  };

  version = "9.4.5";

in

stdenv.mkDerivation rec {
  name = "gitlab-${version}";

  buildInputs = [
    ruby-env ruby bundler tzdata git nodejs procps dpkg yarn
  ];

  src = fetchFromGitHub {
    owner = "gitlabhq";
    repo = "gitlabhq";
    rev = "v${version}";
    sha256 = "1jdvgpzkrap9n9pclyi5ln5l5qfhj4y8ygb1w90jkgrd785bg573";
  };

  patches = [
    ./remove-hardcoded-locations.patch
    ./nulladapter.patch
  ];

  postPatch = ''
    # For reasons I don't understand "bundle exec" ignores the
    # RAILS_ENV causing tests to be executed that fail because we're
    # not installing development and test gems above. Deleting the
    # tests works though.:
    rm lib/tasks/test.rake

    rm config/initializers/gitlab_shell_secret_token.rb

    substituteInPlace app/controllers/admin/background_jobs_controller.rb \
        --replace "ps -U" "${procps}/bin/ps -U"

    # required for some gems:
    cat > config/database.yml <<EOF
      production:
        adapter: <%= ENV["GITLAB_DATABASE_ADAPTER"] || sqlite %>
        database: gitlab
        host: <%= ENV["GITLAB_DATABASE_HOST"] || "127.0.0.1" %>
        password: <%= ENV["GITLAB_DATABASE_PASSWORD"] || "blerg" %>
        username: gitlab
        encoding: utf8
    EOF
  '';

  buildPhase = ''
    mv config/gitlab.yml.example config/gitlab.yml

    # Emulate yarn install --production --pure-lockfile
    mkdir -p node_modules/
    ln -s ${node-env}/node_modules/* node_modules/
    ln -s ${node-env}/node_modules/.bin node_modules/

    # Compile assets. We skip the yarn check because it fails
    export GITLAB_DATABASE_ADAPTER=nulldb
    export SKIP_STORAGE_VALIDATION=true
    rake gettext:compile RAILS_ENV=production
    rake rake:assets:precompile RAILS_ENV=production NODE_ENV=production
    rake webpack:compile RAILS_ENV=production NODE_ENV=production
    rake gitlab:assets:fix_urls RAILS_ENV=production NODE_ENV=production

    mv config/gitlab.yml config/gitlab.yml.example
    rm config/secrets.yml
    mv config config.dist
  '';

  installPhase = ''
    mkdir -p $out/share
    cp -r . $out/share/gitlab
    ln -sf /run/gitlab/uploads $out/share/gitlab/public/uploads
    ln -sf /run/gitlab/config $out/share/gitlab/config

    # rake tasks to mitigate CVE-2017-0882
    # see https://about.gitlab.com/2017/03/20/gitlab-8-dot-17-dot-4-security-release/
    cp ${./reset_token.rake} $out/share/gitlab/lib/tasks/reset_token.rake
  '';

  passthru = {
    inherit ruby-env;
    inherit ruby;
  };
}