feat(auth): fallback to redirect when popup login fails

Author: shadowdevcode

src/firebase.ts

@@ -1,5 +1,5 @@
 import { initializeApp } from 'firebase/app';
-import { getAuth, GoogleAuthProvider, signInWithPopup, signOut } from 'firebase/auth';
+import { AuthError, getAuth, GoogleAuthProvider, signInWithPopup, signInWithRedirect, signOut } from 'firebase/auth';
 import { getFirestore } from 'firebase/firestore';
 import firebaseConfig from '../firebase-applet-config.json';
 
@@ -8,7 +8,53 @@ export const db = getFirestore(app, firebaseConfig.firestoreDatabaseId);
 export const auth = getAuth(app);
 export const googleProvider = new GoogleAuthProvider();
 
-export const loginWithGoogle = () => signInWithPopup(auth, googleProvider);
+const REDIRECT_ELIGIBLE_POPUP_ERROR_CODES: ReadonlySet<string> = new Set([
+  'auth/popup-blocked',
+  'auth/popup-closed-by-user',
+  'auth/cancelled-popup-request',
+  'auth/operation-not-supported-in-this-environment',
+]);
+
+function isAuthError(error: unknown): error is AuthError {
+  if (!error || typeof error !== 'object') {
+    return false;
+  }
+
+  const candidate = error as Partial<AuthError>;
+  return typeof candidate.code === 'string';
+}
+
+function shouldFallbackToRedirect(error: AuthError): boolean {
+  return REDIRECT_ELIGIBLE_POPUP_ERROR_CODES.has(error.code);
+}
+
+export const loginWithGoogle = async (): Promise<void> => {
+  try {
+    await signInWithPopup(auth, googleProvider);
+  } catch (error) {
+    if (isAuthError(error) && shouldFallbackToRedirect(error)) {
+      // COOP/preview-related popup constraints can be non-fatal; redirect login remains valid.
+      console.warn('google_login_popup_failed_redirect_fallback', {
+        code: error.code,
+        message: error.message,
+      });
+      await signInWithRedirect(auth, googleProvider);
+      return;
+    }
+
+    if (isAuthError(error)) {
+      console.error('google_login_failed', {
+        code: error.code,
+        message: error.message,
+      });
+      throw error;
+    }
+
+    console.error('google_login_failed_unknown_error', { error });
+    throw error;
+  }
+};
+
 export const logout = () => signOut(auth);
 
 export enum OperationType {