{ lib, config, options, ... }:
let

  driveModule = lib.types.submodule {
    options = {
      name = lib.mkOption {
        type = lib.types.str;
        description = ''
          The path of the drive.
          Note that a / is already added at the beginning.
        '';
        default = "";
        example = "drive2";
      };
      drive = lib.mkOption {
        type = lib.types.attrsOf lib.types.anything;
        description = "The attrs of the drive";
        default = { };
        example = {
          device = "/dev/disk/by-label/DRIVE2";
          fsType = "ext4";
          options = [ "noatime" "nodiratime" "discard" ];
        };
      };
    };
  };
in {
  options.mods = {
    useSwap = {
      enable = lib.mkOption {
        default = true;
        example = false;
        type = lib.types.bool;
        description = ''
          Use default drive config
        '';
      };
    };
    defaultDrives = {
      enable = lib.mkOption {
        default = true;
        example = false;
        type = lib.types.bool;
        description = ''
          Use default drive config
        '';
      };
    };
    extraDrives = lib.mkOption {
      default = [

      ];
      example = [{
        name = "drive2";
        drive = {
          device = "/dev/disk/by-label/DRIVE2";
          fsType = "ext4";
          options = [ "noatime" "nodiratime" "discard" ];
        };
      }];
      #  TODO:  how to make this work
      # type = with lib.types; listOf (attrsOf driveModule);
      type = with lib.types; listOf (attrsOf anything);
      description = ''
        Extra drives to add.
      '';
    };
  };

  config = (lib.optionalAttrs (options ? fileSystems) {
    fileSystems = builtins.listToAttrs (map ({ name, drive }: {
      name = "/" + name;
      value = drive;
    }) config.mods.extraDrives)
      // (lib.optionalAttrs config.mods.defaultDrives.enable) {
        "/" = {
          device = "/dev/disk/by-label/ROOT";
          fsType = "btrfs";
          options = [ "noatime" "nodiratime" "discard" ];
        };

        "/boot" = {
          device = "/dev/disk/by-label/BOOT";
          fsType = "vfat";
          options = [ "rw" "fmask=0022" "dmask=0022" "noatime" ];
        };

        "/home" = {
          device = "/dev/disk/by-label/HOME";
          fsType = "btrfs";
          options = [ "noatime" "nodiratime" "discard" ];
        };
      };
    # TODO make this convert to choice of drives -> thanks to funny types this doesn't work...
    swapDevices = lib.mkIf config.mods.useSwap.enable [{
      device = "/dev/disk/by-label/SWAP";
    }];
  });
}