arrpc: add module

modules/services/arrpc.nix

@@ -0,0 +1,39 @@
+{ config, pkgs, lib, ... }:
+let
+  inherit (lib) mkIf mkOption mkPackageOption mkEnableOption types;
+
+  cfg = config.services.arrpc;
+in {
+  meta.maintainers = [ lib.maintainers.NotAShelf ];
+
+  options.services.arrpc = {
+    enable = mkEnableOption "arrpc";
+    package = mkPackageOption pkgs "arrpc" { };
+
+    systemdTarget = mkOption {
+      type = types.str;
+      default = "graphical-session.target";
+      example = "sway-session.target";
+      description = ''
+        Systemd target to bind to.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.user.services.arRPC = {
+      Unit = {
+        Description =
+          "Discord Rich Presence for browsers, and some custom clients";
+        PartOf = [ "graphical-session.target" ];
+      };
+
+      Service = {
+        ExecStart = lib.getExe cfg.package;
+        Restart = "always";
+      };
+
+      Install.WantedBy = [ cfg.systemdTarget ];
+    };
+  };
+}