{
  home ? throw "home argument is required",
}:
{ config, lib, ... }:
let
  cfg = config.xdg;
in
{
  options.xdg =
    with lib;
    with types;
    {
      relativeCacheHome = mkOption {
        type = str;
        readOnly = true;
        default = ".cache";
        description = "Relative path to directory holding application caches.";
      };

      relativeConfigHome = mkOption {
        type = str;
        readOnly = true;
        default = ".config";
        description = "Relative path to directory holding application configurations.";
      };

      relativeDataHome = mkOption {
        type = str;
        readOnly = true;
        default = ".local/share";
        description = "Relative path to directory holding application data.";
      };

      relativeStateHome = mkOption {
        type = str;
        readOnly = true;
        default = ".local/state";
        description = "Relative path to directory holding application states.";
      };

      userDirs = {
        relativeDesktop = mkOption {
          type = str;
          readOnly = true;
          default = "Desktop";
          description = "Relative path to the Desktop directory.";
        };

        relativeDocuments = mkOption {
          type = str;
          readOnly = true;
          default = "Documents";
          description = "Relative path to the Documents directory.";
        };

        relativeDownload = mkOption {
          type = str;
          readOnly = true;
          default = "Downloads";
          description = "Relative path to the Downloads directory.";
        };

        relativeMusic = mkOption {
          type = str;
          readOnly = true;
          default = "Music";
          description = "Relative path to the Music directory.";
        };

        relativePictures = mkOption {
          type = str;
          readOnly = true;
          default = "Pictures";
          description = "Relative path to the Pictures directory.";
        };

        relativeTemplates = mkOption {
          type = str;
          readOnly = true;
          default = "Templates";
          description = "Relative path to the Templates directory.";
        };

        relativeVideos = mkOption {
          type = str;
          readOnly = true;
          default = "Videos";
          description = "Relative path to the Videos directory.";
        };
      };
    };

  config.xdg =
    with lib;
    with cfg;
    {
      cacheHome = mkDefault "${home}/${relativeCacheHome}";
      configHome = mkDefault "${home}/${relativeConfigHome}";
      dataHome = mkDefault "${home}/${relativeDataHome}";
      stateHome = mkDefault "${home}/${relativeStateHome}";

      userDirs = with userDirs; {
        desktop = mkDefault "${home}/${relativeDesktop}";
        documents = mkDefault "${home}/${relativeDocuments}";
        download = mkDefault "${home}/${relativeDownload}";
        music = mkDefault "${home}/${relativeMusic}";
        pictures = mkDefault "${home}/${relativePictures}";
        templates = mkDefault "${home}/${relativeTemplates}";
        videos = mkDefault "${home}/${relativeVideos}";
      };
    };
}