{ config, pkgs, lib, ... }:

{
  options.genode = with lib;
    let
      genodeOpts = { ... }: {
        options = {

          name = mkOption {
            example = "webserver";
            type = types.str;
            description = "Name of the Genode subsystem.";
          };

          depot = mkOption {
            type = with types; attrsOf package;
            description = ''
              Attribute set of Genode depot binaries.
            '';
          };

          pkgs = mkOption {
            type = with types; attrsOf package;
            description = ''
              Attribute set of Genode packages.
            '';
          };

          config = mkOption {
            type = types.str;
            default = "<config/>";
            description = ''
              Configuration of the Genode subsystem.
              Must be rendering in the Genode XML format.
            '';
          };

          rom = mkOption {
            type = with types; attrs;
            example = literalExample {
              nic_drv = "${depot.ipxe_nic_drv}/bin/ipxe_nic_drv";
            };
          };
        };
      };

    in mkOption {
      type = with lib.types; loaOf (submodule genodeOpts);
      default = { };
      example = {
        foobar = {
          config = "<empty/>";
          rom = { };
        };
      };
      description = ''
        Configurations of Genode subsystems
      '';
    };

  config = {

    systemd.services = let
      toService = name: cfg: {
        description = "Genode subsystem";
        wantedBy = [ "multi-user.target" ];

        preStart = let
          rom' = with cfg.pkgs;
            {
              core = "${base-linux}/bin/core-linux";
              init = "${os}/bin/init";
              "ld.lib.so" = "${cfg.depot.base-linux}/lib/ld.lib.so";
              timer = "${base-linux}/bin/linux_timer_drv";
              config = builtins.toFile "${name}.config.xml" cfg.config;
            } // cfg.rom;
        in builtins.concatStringsSep "\n"
        (lib.mapAttrsToList (name: value: "ln -s ${value} ${name}") rom');

        serviceConfig = {
          DynamicUser = true;
          RuntimeDirectory = "genode/" + name;
          WorkingDirectory = "/run/genode/" + name;
          ExecStart = "${cfg.pkgs.base-linux}/bin/core-linux";
        };
      };
    in lib.mapAttrs toService config.genode;

  };

}