Create NixOS module

flake.nix

@@ -20,6 +20,9 @@
       };
     })
     // {
-      nixosModules = rec {};
+      nixosModules = rec {
+        actual-importer = import ./module.nix self;
+        default = actual-importer;
+      };
     };
 }

module.nix

@@ -0,0 +1,52 @@
+self: {
+  config,
+  pkgs,
+  lib,
+  system,
+  ...
+}: let
+  cfg = config.programs.actual-importer;
+
+  appConfig = (pkgs.formats.yaml {}).generate "actual-importer.config.yaml" cfg.config;
+
+  app = pkgs.writeShellApplication {
+    name = "actual-importer";
+    runtimeInputs = [self.packages.${system}.default];
+    text = ''
+      actual-importer -c "${appConfig}" "$@";
+    '';
+  };
+in
+  with lib; {
+    options.programs.actual-importer = {
+      enable = mkEnableOption "actual-importer";
+
+      config = mkOption {
+        type = types.attrs;
+        description = "The actual-importer config which will be eventually converted to yaml";
+        example = {
+          defaultProfile = "my-bank";
+          profiles = {
+            my-bank = {
+              parser = "pl.ing";
+            };
+          };
+
+          defaultServer = "main-server";
+          servers = {
+            mainServer = {
+              url = "https://my-server.com";
+              budget = "db353760-33d5-4a2a-ab73-5070a6863fe5";
+              account = "60b953ad-ce6c-4427-b727-bf37b4b6dd1b";
+              password = "$__file:/etc/passwords/actual.key";
+              data = "/tmp/actual";
+            };
+          };
+        };
+      };
+    };
+
+    config = mkIf cfg.enable {
+      environment.systemPackages = [app];
+    };
+  }