refactor: shared config metadata

modules/features/meta.nix

@@ -25,16 +25,20 @@ let
       user.sourceControl.projectScope
     ];
 
-  hasRequiredScopedEmail =
-    scope: user: scopeEmailCount scope user == 1;
+  hasRequiredScopedEmail = scope: user: scopeEmailCount scope user == 1;
 
   primaryEmailFallback = {
     address = "";
     primary = false;
     scope = null;
-    type = "";
+    type = "mxrouting";
   };
 
+  emailProviderType = lib.types.enum [
+    "mxrouting"
+    "office365"
+  ];
+
   sourceControlScopeType = lib.types.enum [
     "personal"
     "work"
@@ -67,10 +71,11 @@ let
 
         primary = lib.mkOption {
           type = lib.types.bool;
+          default = false;
         };
 
         type = lib.mkOption {
-          type = lib.types.str;
+          type = emailProviderType;
         };
 
         scope = mkNullableOption sourceControlScopeType;
@@ -300,6 +305,29 @@ let
       };
     }
   );
+
+  mkUserEmailAssertions =
+    userName: user:
+    [
+      {
+        assertion = hasSinglePrimaryEmail user;
+        message = "User `${userName}` must define exactly one primary email entry.";
+      }
+    ]
+    ++ (map
+      (scope: {
+        assertion = hasAtMostOneScopedEmail scope user;
+        message = "User `${userName}` may define at most one `${scope}` scoped email entry.";
+      })
+      [
+        "personal"
+        "work"
+      ]
+    )
+    ++ map (scope: {
+      assertion = hasRequiredScopedEmail scope user;
+      message = "User `${userName}` must define exactly one `${scope}` scoped email entry.";
+    }) (requiredSourceControlScopes user);
 in
 {
   flake.modules.nixos.meta =
@@ -309,25 +337,7 @@ in
         type = hostType;
       };
 
-      config.assertions = lib.mapAttrsToList (userName: user: {
-        assertion = hasSinglePrimaryEmail user;
-        message = "User `${userName}` must define exactly one primary email entry.";
-      }) config.meta.host.users
-      ++ lib.flatten (
-        lib.mapAttrsToList (userName: user:
-          (map (scope: {
-            assertion = hasAtMostOneScopedEmail scope user;
-            message = "User `${userName}` may define at most one `${scope}` scoped email entry.";
-          }) [
-            "personal"
-            "work"
-          ])
-          ++ map (scope: {
-            assertion = hasRequiredScopedEmail scope user;
-            message = "User `${userName}` must define exactly one `${scope}` scoped email entry.";
-          }) (requiredSourceControlScopes user)
-        ) config.meta.host.users
-      );
+      config.assertions = lib.flatten (lib.mapAttrsToList mkUserEmailAssertions config.meta.host.users);
     };
 
   flake.modules.homeManager.meta =
@@ -345,22 +355,8 @@ in
         };
       };
 
-      config.assertions = lib.optional (config.meta.user != null) {
-        assertion = hasSinglePrimaryEmail config.meta.user;
-        message = "User `${config.meta.user.name}` must define exactly one primary email entry.";
-      }
-      ++ lib.optionals (config.meta.user != null) (
-        (map (scope: {
-          assertion = hasAtMostOneScopedEmail scope config.meta.user;
-          message = "User `${config.meta.user.name}` may define at most one `${scope}` scoped email entry.";
-        }) [
-          "personal"
-          "work"
-        ])
-        ++ map (scope: {
-          assertion = hasRequiredScopedEmail scope config.meta.user;
-          message = "User `${config.meta.user.name}` must define exactly one `${scope}` scoped email entry.";
-        }) (requiredSourceControlScopes config.meta.user)
+      config.assertions = lib.optionals (config.meta.user != null) (
+        mkUserEmailAssertions config.meta.user.name config.meta.user
       );
     };
 }