app/Http/Controllers/Auth/GoogleAuthController.php

<?php

namespace App\Http\Controllers\Auth;

use App\Http\Controllers\Controller;
use App\Models\User;
use App\Providers\RouteServiceProvider;
use Illuminate\Http\RedirectResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Carbon;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Str;

class GoogleAuthController extends Controller
{
    public function redirect(Request $request): RedirectResponse
    {
        if (! $this->isGoogleLoginConfigured()) {
            return redirect()->route('login')->withErrors([
                'google' => 'Login Google belum dikonfigurasi. Isi GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET, dan GOOGLE_REDIRECT_URI terlebih dulu.',
            ]);
        }

        $state = Str::random(40);

        $request->session()->put('google_oauth_state', $state);

        $query = http_build_query([
            'client_id' => (string) config('services.google.client_id'),
            'redirect_uri' => (string) config('services.google.redirect'),
            'response_type' => 'code',
            'scope' => 'openid profile email',
            'prompt' => 'select_account',
            'access_type' => 'offline',
            'state' => $state,
        ]);

        return redirect()->away('https://accounts.google.com/o/oauth2/v2/auth?'.$query);
    }

    public function callback(Request $request): RedirectResponse
    {
        $storedState = (string) $request->session()->pull('google_oauth_state', '');
        $returnedState = (string) $request->string('state');

        if ($request->filled('error')) {
            return redirect()->route('login')->withErrors([
                'google' => 'Login Google dibatalkan atau ditolak oleh pengguna.',
            ]);
        }

        if ($storedState === '' || ! hash_equals($storedState, $returnedState)) {
            return redirect()->route('login')->withErrors([
                'google' => 'Sesi login Google tidak valid. Coba ulangi lagi.',
            ]);
        }

        if (! $this->isGoogleLoginConfigured()) {
            return redirect()->route('login')->withErrors([
                'google' => 'Login Google belum dikonfigurasi di server.',
            ]);
        }

        $tokenResponse = Http::asForm()
            ->timeout(20)
            ->post('https://oauth2.googleapis.com/token', [
                'code' => (string) $request->string('code'),
                'client_id' => (string) config('services.google.client_id'),
                'client_secret' => (string) config('services.google.client_secret'),
                'redirect_uri' => (string) config('services.google.redirect'),
                'grant_type' => 'authorization_code',
            ]);

        if (! $tokenResponse->ok() || ! $tokenResponse->json('access_token')) {
            return redirect()->route('login')->withErrors([
                'google' => 'Google tidak mengembalikan access token yang valid.',
            ]);
        }

        $googleProfile = Http::withToken((string) $tokenResponse->json('access_token'))
            ->timeout(20)
            ->get('https://openidconnect.googleapis.com/v1/userinfo');

        if (! $googleProfile->ok()) {
            return redirect()->route('login')->withErrors([
                'google' => 'Profil akun Google tidak bisa diambil saat ini.',
            ]);
        }

        $profile = $googleProfile->json();
        $googleId = trim((string) data_get($profile, 'sub', ''));
        $email = Str::lower(trim((string) data_get($profile, 'email', '')));

        if ($googleId === '' || $email === '') {
            return redirect()->route('login')->withErrors([
                'google' => 'Data akun Google tidak lengkap. Pastikan email tersedia di akun Google Anda.',
            ]);
        }

        $user = User::query()
            ->where('google_id', $googleId)
            ->orWhere('email', $email)
            ->first();

        if (! $user) {
            $user = User::create([
                'name' => trim((string) data_get($profile, 'name', Str::before($email, '@'))),
                'email' => $email,
                'google_id' => $googleId,
                'email_verified_at' => data_get($profile, 'email_verified') ? Carbon::now() : null,
                'password' => Hash::make(Str::random(40)),
            ]);
        } else {
            $user->forceFill([
                'name' => $user->name ?: trim((string) data_get($profile, 'name', Str::before($email, '@'))),
                'google_id' => $user->google_id ?: $googleId,
            ]);

            if (! $user->email_verified_at && data_get($profile, 'email_verified')) {
                $user->email_verified_at = Carbon::now();
            }

            $user->save();
        }

        Auth::login($user, true);
        $request->session()->regenerate();

        return redirect()->intended(RouteServiceProvider::HOME);
    }

    private function isGoogleLoginConfigured(): bool
    {
        return filled(config('services.google.client_id'))
            && filled(config('services.google.client_secret'))
            && filled(config('services.google.redirect'));
    }
}