improve registration and add oauth

app/controllers/omniauth_callbacks_controller.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class OmniauthCallbacksController < Devise::OmniauthCallbacksController
+  def google_oauth2
+    @user = Users.from_omniauth(request.env['omniauth.auth'])
+
+    if @user.persisted?
+      flash[:notice] = I18n.t('devise.omniauth_callbacks.success', kind: 'Google')
+
+      sign_in_and_redirect @user, event: :authentication
+    else
+      redirect_to new_registration_path(oauth_callback: true, user: @user.slice(:email, :first_name, :last_name)),
+                  notice: 'Please complete registration with Google auth'
+    end
+  end
+end