Add nixos module and overlay

flake.nix

@@ -51,9 +51,18 @@
       };
     });
 
+    overlays = {
+      default = self.overlays.greg-ng;
+      greg-ng = final: prev: {
+        inherit (self.packages.${prev.system}) greg-ng;
+      };
+    };
+
     packages = forAllSystems (system: pkgs: _: {
       default = self.packages.${system}.greg-ng;
       greg-ng = pkgs.callPackage ./default.nix { };
     });
+  } // {
+    nixosModules.default = ./module.nix;
   };
 }

module.nix

@@ -0,0 +1,98 @@
+{ config, pkgs, lib, ... }:
+let
+  cfg = config.services.greg-ng;
+in
+{
+  options.services.greg-ng = {
+    enable = lib.mkEnableOption "greg-ng, an mpv based media player";
+
+    package = lib.mkPackageOption pkgs "greg-ng" { };
+
+    mpvPackage = lib.mkPackageOption pkgs "mpv" { };
+
+    # TODO: create some better descriptions
+    settings = {
+      host = lib.mkOption {
+        type = lib.types.str;
+        default = "localhost";
+        example = "0.0.0.0";
+        description = ''
+          Which host to bind to.
+        '';
+      };
+
+      port = lib.mkOption {
+        type = lib.types.port;
+        default = 8008;
+        example = 10008;
+        description = ''
+          Which port to bind to.
+        '';
+      };
+
+      mpv-socket-path = lib.mkOption {
+        type = lib.types.str;
+        default = "%t/greg-ng-mpv.sock";
+        description = ''
+          Path to the mpv socket.
+        '';
+      };
+
+      mpv-executable-path = lib.mkOption {
+        type = lib.types.str;
+        default = lib.getExe cfg.mpvPackage;
+        defaultText = lib.literalExpression ''
+          lib.getExe config.services.greg-ng.mpvPackage
+        '';
+        description = ''
+          Path to the mpv executable.
+        '';
+      };
+
+      mpv-config-file = lib.mkOption {
+        type = with lib.types; nullOr str;
+        default = null;
+        description = ''
+          Path to the mpv config file.
+        '';
+      };
+
+      auto-start-mpv = lib.mkOption {
+        type = lib.types.bool;
+        default = true;
+        description = ''
+          Whether to automatically start mpv.
+        '';
+      };
+
+      force-auto-start = lib.mkOption {
+        type = lib.types.bool;
+        default = true;
+        description = ''
+          Whether to force auto starting mpv.
+        '';
+      };
+    };
+  };
+
+  config = {
+    services.cage.enable = true;
+    services.cage.program =let
+      flags = lib.cli.toGNUCommandLineShell { } cfg.settings;
+    in pkgs.writeShellScript "greg-kiosk" ''
+      cd $(mktemp -d)
+
+      ${lib.getExe cfg.package} ${flags}
+    '';
+    services.cage.user = "greg";
+    users.users."greg".isNormalUser = true;
+    system.activationScripts = {
+      base-dirs = {
+        text = ''
+          mkdir -p /nix/var/nix/profiles/per-user/greg
+        '';
+        deps = [];
+      };
+    };
+  };
+}