flake: Add nixos module

flake.nix

@@ -52,5 +52,45 @@
           packages = with pkgs; [rust rust-analyzer];
         };
       formatter = pkgs.alejandra;
-    });
+    }) // {
+      overlays.default = final: prev: {
+        iso7010-a-day = self.packages.${prev.system}.default;
+      };
+
+      nixosModules.default = {
+        config,
+        lib,
+        pkgs,
+        ...
+      }:
+        with lib; let
+          cfg = config.services.iso7010-a-day;
+        in {
+          options.services.iso7010-a-day = {
+            enable = mkEnableOption "Enable the iso7010 bot";
+            environmentFile = mkOption {
+              type = types.path;
+              description = "Path to the environment file";
+            };
+          };
+          config = mkIf cfg.enable {
+            nixpkgs.overlays = [self.overlays.default];
+            systemd.services.iso7010-a-day = {
+              description = "Samw's ISO7010 bot";
+              serviceConfig = {
+                Type = "oneshot";
+                DynamicUser = true;
+                User = "iso7010";
+                ExecStart = "${pkgs.iso7010-a-day}/bin/iso7010_a_day run-bot";
+                EnvironmentFile = cfg.environmentFile;
+              };
+            };
+            systemd.timers.iso7010-a-day = {
+              wantedBy = [ "timers.target" ];
+              partOf = [ "iso7010-a-day.service" ];
+              timerConfig.OnCalendar = [ "*-*-* 12:00:00" ];
+            };
+          };
+        };
+    };
 }