What is the best way to use Google 0Auth - reactjs

Question

I'm trying to use Google OAuth in my App, on the Log In page and the Sign Up page, I'm looking for the best way and the easiest! I tried Passport Js, but I'm stuck right now.
I'm using Mongoose right now and I'm signing up and in users perfectly, but now i want to add a feature where the user can sign in using his google account, I'm looking for a way where the app can get the Email the user is using for his google account and then look if the email is already registered if so redirect him to the home page and if not sign his email up, save it to database, and then redirect to the home page.
This is how my Auth.js looks like
//REGISTER
router.post("/register", async (req, res) => {
try {
//generate new password
const salt = await bcrypt.genSalt(10);
const hashedPass = await bcrypt.hash(req.body.password, salt);
//create new user
const newUser = new User ({
username: req.body.username,
firstName: req.body.firstName,
lastName: req.body.lastName,
email: req.body.email,
password: hashedPass,
repeatPassword: hashedPass,
birthday: req.body.birthday,
});
//save user and respond
const user = await newUser.save();
res.status(200).json(user);
} catch (err) {
res.status(500).json(err);
}
});
//LOGIN
router.post("/login", async (req, res) => {
try {
const user = await User.findOne({ email: req.body.email });
// if(!user) return res.status(400).json("Wrong credentials!");
!user && res.status(400).json("Wrong credentials!");
const validated = await bcrypt.compare(req.body.password, user.password);
// if(!validated) return res.status(400).json("Wrong credentials!");
!validated && res.status(400).json("Wrong credentials!");
const { password, ...others } = user._doc;
return res.status(200).json(others);
} catch (err) {
return res.status(500).json(err);
}
});
PassportJs configuration I used: but didn't work
passport.use(
new GoogleStrategy(
{
clientID: "MyClientId",
clientSecret: "Myclientsecret",
callbackURL: "/api/auth/google/callback",
},
function (accessToken, refreshToken, profile, done) {
User.find(
{
social: profile.provider,
social_id: profile.id,
},
(err, user) => {
if (user.length === 0) {
const user = new User({
email: profile.email,
username: profile.displayName,
profilePic: profile.photos[0],
social: profile.provider,
social_id: profile.id,
});
const userModel = new User(data);
userModel.save();
done(null, profile);
}
if (err) {
return done(err);
}
},
);
return done(null, profile);
}
)
);
passport.serializeUser((user, done) => {
done(null, user);
});
passport.deserializeUser((user, done) => {
done(null, user);
});
router.get("/login/success", (req, res) => {
if (req.user) {
res.status(200).json({
success: true,
message: "successfull",
user: req.user,
// cookies: req.cookies
});
}
});
router.get("/login/failed", (req, res) => {
res.status(401).json({
success: false,
message: "failure",
});
});
router.get("/google", passport.authenticate("google", { scope: ["profile"] }));
router.get(
"/google/callback",
passport.authenticate("google", {
successRedirect: CLIENT_URL,
failureRedirect: "/login/failed",
})
);