routes.php

<?php

// http://home.flynsarmy.com/flynsarmy/sociallogin/Google?s=/&f=/login
Route::get(
    'flynsarmy/sociallogin/{provider}',
    [
        "as" => "flynsarmy_sociallogin_provider",
        'middleware' => ['web'],
        function ($provider_name, $action = "") {
            $success_redirect = Input::get('s', '/');
            $error_redirect = Input::get('f', '/login');
            Session::flash('flynsarmy_sociallogin_successredirect', $success_redirect);
            Session::flash('flynsarmy_sociallogin_errorredirect', $error_redirect);

            $provider_class = Flynsarmy\SocialLogin\Classes\ProviderManager::instance()
                ->resolveProvider($provider_name);

            if (!$provider_class) {
                return Redirect::to($error_redirect)->withErrors("Unknown login provider: $provider_name.");
            }

            $provider = $provider_class::instance();

            return $provider->redirectToProvider();
        }
    ]
)->where(['provider' => '[A-Z][a-zA-Z ]+']);

Route::any(
    'flynsarmy/sociallogin/{provider}/callback',
    [
        'as' => 'flynsarmy_sociallogin_provider_callback',
        'middleware' => ['web'],
        function ($provider_name) {
            $success_redirect = Session::get('flynsarmy_sociallogin_successredirect', '/');
            $error_redirect = Session::get('flynsarmy_sociallogin_errorredirect', '/login');

            $provider_class = Flynsarmy\SocialLogin\Classes\ProviderManager::instance()
                ->resolveProvider($provider_name);

            if (!$provider_class) {
                return Redirect::to($error_redirect)->withErrors("Unknown login provider: $provider_name.");
            }

            $provider = $provider_class::instance();

            try {
                // This will contain [token => ..., email => ..., ...]
                $provider_response = $provider->handleProviderCallback($provider_name);

                if (!is_array($provider_response)) {
                    return Redirect::to($error_redirect);
                }
            } catch (Exception $e) {
                // Log the error
                Log::error($e->getMessage() . ' in ' . $e->getFile() . ' on line ' . $e->getLine());

                return Redirect::to($error_redirect)->withErrors([$e->getMessage()]);
            }

            ksort($provider_response['token']);

            $provider_details = [
                'provider_id' => $provider_name,
                'provider_token' => $provider_response['token'],
            ];
            $user_details = $provider_response['profile'];

            // Backend logins
            if ($success_redirect == Backend::url()) {
                $user = Flynsarmy\SocialLogin\Classes\UserManager::instance()
                    ->findBackendUserByEmail($user_details->email);

                if (!$user) {
                    throw new October\Rain\Auth\AuthException(sprintf(
                        'Administrator with email address "%s" not found.',
                        $user_details['email']
                    ));
                }

                // Support custom login handling
                $result = Event::fire('flynsarmy.sociallogin.handleBackendLogin', [
                    $provider_details, $provider_response, $user
                ], true);
                if ($result) {
                    return $result;
                }

                BackendAuth::login($user, true);

                // Load version updates
                System\Classes\UpdateManager::instance()->update();

                // Log the sign in event
                Backend\Models\AccessLog::add($user);

            // Frontend Logins
            } else {
                // Grab the user associated with this provider. Creates or attach one if need be.
                $user = \Flynsarmy\SocialLogin\Classes\UserManager::instance()->find(
                    $provider_details,
                    $user_details
                );

                // Support custom login handling
                $result = Event::fire('flynsarmy.sociallogin.handleLogin', [
                    $provider_details, $provider_response, $user
                ], true);
                if ($result) {
                    return $result;
                }

                Auth::login($user);
            }

            return Redirect::to($success_redirect);
        }
    ]
);