{ config, lib, ... }:
let
  cfg = config.xdg;
in
{
  options.xdg =
    with lib;
    with types;
    {
      relativeCacheHome = mkOption {
        type = str;
        default = ".cache";
        description = "Relative path to directory holding application caches.";
      };

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

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

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

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

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

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

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

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

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

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

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

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