nix: break out appview module into separate file

Signed-off-by: oppiliappan <[e-mail]>

flake.nix

···
       };
     });
 
-    nixosModules.appview = {
-      config,
-      pkgs,
-      lib,
-      ...
-    }:
-      with lib; {
-        options = {
-          services.tangled-appview = {
-            enable = mkOption {
-              type = types.bool;
-              default = false;
-              description = "Enable tangled appview";
-            };
-            port = mkOption {
-              type = types.int;
-              default = 3000;
-              description = "Port to run the appview on";
-            };
-            cookie_secret = mkOption {
-              type = types.str;
-              default = "00000000000000000000000000000000";
-              description = "Cookie secret";
-            };
-          };
-        };
-
-        config = mkIf config.services.tangled-appview.enable {
-          systemd.services.tangled-appview = {
-            description = "tangled appview service";
-            wantedBy = ["multi-user.target"];
-
-            serviceConfig = {
-              ListenStream = "0.0.0.0:${toString config.services.tangled-appview.port}";
-              ExecStart = "${self.packages.${pkgs.system}.appview}/bin/appview";
-              Restart = "always";
-            };
-
-            environment = {
-              TANGLED_DB_PATH = "appview.db";
-              TANGLED_COOKIE_SECRET = config.services.tangled-appview.cookie_secret;
-            };
-          };
-        };
-      };
-
     nixosModules.knot = {
       config,
       pkgs,
···
         })
       ];
     };
+    nixosModules.appview = import ./nix/modules/appview.nix {inherit self;};
   };
 }

nix/modules/appview.nix

···
+{self}: {
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+with lib; {
+  options = {
+    services.tangled-appview = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = "Enable tangled appview";
+      };
+      port = mkOption {
+        type = types.int;
+        default = 3000;
+        description = "Port to run the appview on";
+      };
+      cookie_secret = mkOption {
+        type = types.str;
+        default = "00000000000000000000000000000000";
+        description = "Cookie secret";
+      };
+    };
+  };
+
+  config = mkIf config.services.tangled-appview.enable {
+    systemd.services.tangled-appview = {
+      description = "tangled appview service";
+      wantedBy = ["multi-user.target"];
+
+      serviceConfig = {
+        ListenStream = "0.0.0.0:${toString config.services.tangled-appview.port}";
+        ExecStart = "${self.packages.${pkgs.system}.appview}/bin/appview";
+        Restart = "always";
+      };
+
+      environment = {
+        TANGLED_DB_PATH = "appview.db";
+        TANGLED_COOKIE_SECRET = config.services.tangled-appview.cookie_secret;
+      };
+    };
+  };
+}