fix: issue with color scheme in layout (#1168)

* fix: issue with color scheme in layout

* test: add and adjust unit tests for sign-in-callback

packages/auth/callbacks.ts

@@ -1,5 +1,6 @@
 import { cookies } from "next/headers";
 import type { Adapter } from "@auth/core/adapters";
+import dayjs from "dayjs";
 import type { NextAuthConfig } from "next-auth";
 
 import type { Database } from "@homarr/db";
@@ -52,12 +53,12 @@ export const createSessionCallback = (db: Database): NextAuthCallbackOf<"session
 };
 
 export const createSignInCallback =
-  (adapter: Adapter, isCredentialsRequest: boolean): NextAuthCallbackOf<"signIn"> =>
+  (adapter: Adapter, db: Database, isCredentialsRequest: boolean): NextAuthCallbackOf<"signIn"> =>
   async ({ user }) => {
     if (!isCredentialsRequest) return true;
 
     // https://github.com/nextauthjs/next-auth/issues/6106
-    if (!adapter.createSession) {
+    if (!adapter.createSession || !user.id) {
       return false;
     }
 
@@ -66,8 +67,7 @@ export const createSignInCallback =
 
     await adapter.createSession({
       sessionToken,
-      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      userId: user.id!,
+      userId: user.id,
       expires: sessionExpires,
     });
 
@@ -79,6 +79,21 @@ export const createSignInCallback =
       secure: true,
     });
 
+    const dbUser = await db.query.users.findFirst({
+      where: eq(users.id, user.id),
+      columns: {
+        colorScheme: true,
+      },
+    });
+
+    if (!dbUser) return false;
+
+    // We use a cookie as localStorage is not shared with server (otherwise flickering would occur)
+    cookies().set("homarr-color-scheme", dbUser.colorScheme, {
+      path: "/",
+      expires: dayjs().add(1, "year").toDate(),
+    });
+
     return true;
   };