def self.find_for_oauth(auth, signed_in_resource = nil)

  # Get the identity or create it if it does not exist
  identity = Identity.find_for_oauth(auth)

  user = signed_in_resource ? signed_in_resource : identity.user

  # Create the user if needed (if no logged in user and the identity has no user associated)
  if user.nil?

    # Get the existing user by email if the provider gives us an email.
    # If no email was provided we assign a temporary email and ask the
    # user to verify it on the next step via UsersController.finish_signup
    # email_is_verified = auth.info.email && (auth.info.verified || auth.info.verified_email)
    email = auth.info.email
    user = User.find_by(:email => email) if email

    email ||= "#{TEMP_EMAIL_PREFIX}-#{auth.uid}-#{auth.provider}.com"
    username = auth.info.nickname ? auth.info.nickname :
         ( auth.extra.raw_info.nickname ? auth.extra.raw_info.nickname :
         ( auth.extra.raw_info.username ? auth.extra.raw_info.username : "nickname: " + auth.uid) )
    new_username = username

    # Create the user if it's a new registration.
    # Use default values that will be updated later
    if user.nil?
      # Control if username is taken
      user_same_name = User.find_by(:username => new_username)
      while user_same_name
        rnd = SecureRandom.random_number(10000).to_s
        new_username = username + " (" + rnd + ")"
        user_same_name = User.find_by(:username => new_username)
      end
      user = User.new(
        name: auth.extra.raw_info.name,
        username: new_username,
        email: email,
        password: Devise.friendly_token[0,20],
      )
      user.skip_confirmation!
      user.save!
    end
  end

  # Associate the identity with the user if needed
  if identity.user != user
    identity.user = user
    identity.save!
  end
  user
end