fixed oauth login bug

src/app/api/auth/[...nextauth]/route.ts

@@ -11,7 +11,7 @@ import {
   accounts,
   verificationTokens,
 } from "@/app/db/schema/users";
-import { eq } from "drizzle-orm";
+import { eq, and } from "drizzle-orm";
 
 // ------------------------------------------------------------------
 // Environment variables
@@ -102,7 +102,7 @@ export const AuthOptions: NextAuthOptions = {
     /**
      * Sign in callback — ensures user exists and links OAuth provider if needed
      */
-    async signIn({ user, account }) {
+    async signIn({ user, account, profile }) {
       try {
         if (!user?.email) return false;
         const normalisedEmail = user.email.toLowerCase();
@@ -113,11 +113,50 @@ export const AuthOptions: NextAuthOptions = {
           .from(users)
           .where(eq(users.email, normalisedEmail));
 
+        // New user - next auth will handle
         if (!dbUser) {
           console.log("New user sign up for email:", normalisedEmail);
           return true;
         }
 
+        // Auto-link provider if same verified email but account not linked yet
+        if (account?.provider && account.type === "oauth") {
+          const existingLink = await db
+            .select()
+            .from(accounts)
+            .where(
+              and(
+                eq(accounts.userId, dbUser.id),
+                eq(accounts.provider, account.provider)
+              )
+            );
+
+          const emailVerified =
+            (profile as any)?.email_verified ?? account.provider === "google";
+
+          if (existingLink.length === 0 && emailVerified) {
+            // This handles the case where we had not set up accounts but
+            // signed up users with oauth
+            console.log(
+              `Linking ${account.provider} account for user ${normalisedEmail}`
+            );
+
+            await db
+              .insert(accounts)
+              .values({
+                userId: dbUser.id,
+                type: account.type,
+                provider: account.provider,
+                providerAccountId: account.providerAccountId,
+                access_token: account.access_token,
+                id_token: account.id_token,
+                refresh_token: account.refresh_token,
+                expires_at: account.expires_at,
+              })
+              .onConflictDoNothing();
+          }
+        }
+
         // Link OAuth ID if missing (helps for older accounts)
         if (account && !dbUser.oauthId) {
           console.log("Linking OAuth ID for user:", normalisedEmail);