refactor(copyparty): derive effective volume defaults

configs/nixos/modules/services/copyparty.nix

@@ -19,6 +19,15 @@ let
   writableVolumes = lib.filter (volume: !volume.readOnly) (lib.attrValues cfg.volumes);
 
   port = 3923;
+  defaultAccess = {
+    A = [ accountName ];
+  };
+
+  defaultWritableFlags = {
+    d2d = true;
+    d2t = true;
+    dthumb = true;
+  };
 
   credentialHash = builtins.substring 0 16 (builtins.hashString "sha256" accountName);
 
@@ -58,11 +67,9 @@ let
     );
 
   renderedVolumes = lib.mapAttrs (_urlPath: volume: {
-    inherit (volume)
-      access
-      path
-      ;
-    flags = volumeFlags volume.flags;
+    inherit (volume) path;
+    access = if volume.readOnly then { r = [ accountName ]; } else defaultAccess // volume.access;
+    flags = volumeFlags (lib.optionalAttrs (!volume.readOnly) defaultWritableFlags // volume.flags);
   }) cfg.volumes;
 
   configText = util.formats.copyparty.render {
@@ -89,49 +96,38 @@ in
 
     volumes = lib.mkOption {
       type = lib.types.attrsOf (
-        lib.types.submodule (
-          { config, ... }:
-          {
-            options = {
-              path = lib.mkOption {
-                type = lib.types.externalPath;
-                description = "Sets the filesystem path served by this volume.";
-              };
-
-              access = lib.mkOption {
-                type = lib.types.attrsOf (lib.types.listOf lib.types.str);
-                default = if config.readOnly then { r = [ accountName ]; } else { A = [ accountName ]; };
-                example = {
-                  A = [ "alexion" ];
-                };
-                description = "Maps Copyparty permission strings to account names.";
-              };
-
-              readOnly = lib.mkOption {
-                type = lib.types.bool;
-                default = false;
-                description = "Serves this volume read-only.";
-              };
-
-              flags = lib.mkOption {
-                type = lib.types.attrs;
-                default =
-                  if config.readOnly then
-                    { }
-                  else
-                    {
-                      d2d = true;
-                      d2t = true;
-                      dthumb = true;
-                    };
-                example = {
-                  dthumb = true;
-                };
-                description = "Sets Copyparty volume flags.";
-              };
+        lib.types.submodule {
+          options = {
+            path = lib.mkOption {
+              type = lib.types.externalPath;
+              description = "Sets the filesystem path served by this volume.";
             };
-          }
-        )
+
+            access = lib.mkOption {
+              type = lib.types.attrsOf (lib.types.listOf lib.types.str);
+              default = { };
+              example = {
+                A = [ "alexion" ];
+              };
+              description = "Maps Copyparty permission strings to account names.";
+            };
+
+            readOnly = lib.mkOption {
+              type = lib.types.bool;
+              default = false;
+              description = "Serves this volume read-only.";
+            };
+
+            flags = lib.mkOption {
+              type = lib.types.attrs;
+              default = { };
+              example = {
+                dthumb = true;
+              };
+              description = "Sets Copyparty volume flags.";
+            };
+          };
+        }
       );
       default = { };
       description = "Defines Copyparty volumes by URL path.";