##
# If OPENPROJECT_AUTH__SOURCE__SSO_HEADER and OPENPROJECT_AUTH__SOURCE__SSO_SECRET are
# configured OpenProject will login the user given in the HTTP header with the given name
# together with the secret in the form of `login:$secret`.
module AuthSourceSSO
  def find_current_user
    user = super

    return user if user || sso_in_progress!

    if login = read_sso_login
      user = find_user_from_auth_source(login) || create_user_from_auth_source(login)

      handle_sso_for! user, login
    end
  end

  def read_sso_login
    return nil unless header_name && secret

    login, given_secret = String(request.headers[header_name]).split(":")

    login if valid_credentials? login, given_secret
  end

  def sso_config
    @sso_config ||= OpenProject::Configuration.auth_source_sso.try(:with_indifferent_access)
  end

  def header_name
    sso_config && sso_config[:header]
  end

  def secret
    sso_config && sso_config[:secret]
  end

  def valid_credentials?(login, secret)
    !invalid_credentials?(login, secret)
  end

  def invalid_credentials?(login, secret)
    if secret != self.secret.to_s
      Rails.logger.error(
        "Secret contained in auth source SSO header not valid. " +
        "(#{header_name}: #{request.headers[header_name]})"
      )

      true
    elsif login.nil?
      Rails.logger.error(
        "No login contained in auth source SSO header. " +
        "(#{header_name}: #{request.headers[header_name]})"
      )

      true
    end
  end

  def find_user_from_auth_source(login)
    User.where(login: login).where.not(auth_source_id: nil).first
  end

  def create_user_from_auth_source(login)
    if attrs = AuthSource.find_user(login)
      # login is both safe and protected in chilis core code
      # in case it's intentional we keep it that way
      user = User.new attrs.except(:login)
      user.login = login
      user.language = Setting.default_language

      save_user! user

      user
    end
  end

  def save_user!(user)
    if user.save
      user.reload

      if logger && user.auth_source
        logger.info(
          "User '#{user.login}' created from external auth source: " +
          "#{user.auth_source.type} - #{user.auth_source.name}"
        )
      end
    end
  end

  def sso_in_progress!
    sso_failure_in_progress! || session[:auth_source_registration]
  end

  def sso_failure_in_progress!
    failure = session[:auth_source_sso_failure]

    if failure
      if failure[:ttl] > 0
        session[:auth_source_sso_failure] = failure.merge(ttl: failure[:ttl] - 1)
      else
        session.delete :auth_source_sso_failure

        nil
      end
    end
  end

  def sso_login_failed?(user)
    user.nil? || user.new_record? || !user.active?
  end

  def handle_sso_for!(user, login)
    if sso_login_failed?(user)
      handle_sso_failure! user, login
    else # valid user
      handle_sso_success user
    end
  end

  def handle_sso_success(user)
    session[:user_id] = user.id

    user
  end

  def handle_sso_failure!(user, login)
    session[:auth_source_sso_failure] = {
      user: user,
      login: login,
      back_url: request.base_url + request.original_fullpath,
      ttl: 1
    }

    redirect_to sso_failure_path
  end
end