ludusavi: create Ludusavi module

modules/lib/maintainers.nix

@@ -551,6 +551,11 @@
     github = "pedorich-n";
     githubId = 15573098;
   };
+  PopeRigby = {
+    name = "PopeRigby";
+    github = "poperigby";
+    githubId = 20866468;
+  };
   liyangau = {
     name = "Li Yang";
     email = "d@aufomm.com";

modules/services/ludusavi.nix

@@ -0,0 +1,86 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.services.ludusavi;
+  settingsFormat = pkgs.formats.yaml { };
+
+  configFile =
+    if cfg.configFile == null then
+      settingsFormat.generate "config.yaml" cfg.settings
+    else
+      cfg.configFile;
+in
+{
+  meta.maintainers = [ lib.maintainers.PopeRigby ];
+
+  options.services.ludusavi = {
+    enable = lib.mkEnableOption "Ludusavi game backup tool";
+    configFile = lib.mkOption {
+      type = with lib.types; nullOr path;
+      default = null;
+      description = ''
+        Path to a Ludusavi `config.yaml`. Mutually exclusive with the `settings` option.
+        See https://github.com/mtkennerly/ludusavi#configuration-file for available options.
+      '';
+    };
+    settings = lib.mkOption {
+      type = settingsFormat.type;
+      default = {
+        manifest.url = "https://raw.githubusercontent.com/mtkennerly/ludusavi-manifest/master/data/manifest.yaml";
+        roots = [ ];
+        backup.path = "~/.local/state/backups/ludusavi";
+        restore.path = "~/.local/state/backups/ludusavi";
+      };
+      example = {
+        language = "en-US";
+        theme = "light";
+        roots = [
+          {
+            path = "~/.local/share/Steam";
+            store = "steam";
+          }
+        ];
+        backup.path = "~/.local/state/backups/ludusavi";
+        restore.path = "~/.local/state/backups/ludusavi";
+      };
+      description = ''
+        Ludusavi configuration as an attribute set. See
+        https://github.com/mtkennerly/ludusavi#configuration-file
+        for available options.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = (cfg.settings != { }) != (cfg.configFile != null);
+        message = "The `settings` and `configFile` options are mutually exclusive.";
+      }
+    ];
+
+    systemd.user = {
+      services.ludusavi = {
+        Unit.Description = "Run a game save backup with Ludusavi";
+        Service = {
+          Type = "oneshot";
+          ExecStart = "${pkgs.ludusavi}/bin/ludusavi backup --force";
+        };
+      };
+      timers.ludusavi = {
+        Unit.Description = "Run a game save backup with Ludusavi, daily";
+        Timer.OnCalendar = "daily";
+        Install.WantedBy = [ "timers.target" ];
+      };
+    };
+
+    xdg.configFile."ludusavi/config.yaml".source = configFile;
+
+    home.packages = [ pkgs.ludusavi ];
+  };
+}