fetch.rb

  def fresh_access_token
    client = OAuth2::Client.new(strategy[:client_id], strategy[:client_secret])
    OAuth2::AccessToken.new client, fresh_token_record.token
  end

  def fresh_token_record(tries_remaining=1)

    token_record = load_token_record
    need_a_fresh_access_token = !token_record.expires_at or (DateTime.now > token_record.expires_at - 1.minute)
    puts 'need new token ?', need_a_fresh_access_token
    return token_record unless need_a_fresh_access_token

    # see http://stackoverflow.com/a/12574402/18706
    data = {
      :client_id => strategy[:client_id],
      :client_secret => strategy[:client_secret],
      :refresh_token => token_record.refresh_token,
      :grant_type => "refresh_token"
    }
    @response = ActiveSupport::JSON.decode(RestClient.post "https://accounts.google.com/o/oauth2/token", data)
    if @response["access_token"].present?
      token_record.update_attributes(
        token: @response["access_token"],
        expires_at: DateTime.now + @response["expires_in"].seconds - 10.seconds # expires_in should normally be 3600
      )
      token_record
    else
      logger.info "No token exchanged for user token #{token_record.inspect}"
    end
  rescue => e
    logger.error "Could not call to exchange token, or had a problem receiving it. #{token_record.inspect}. Error Was:\n {e.inspect}"
    nil
  end

  def verified_token
    get "https://www.googleapis.com/oauth2/v1/tokeninfo?access_token=#{fresh_token_record.token}"
  end

  def get(url)
    puts "GET", url
    response = fresh_access_token.get url
  end

  def get_json(url)
    Hashie::Mash.new(JSON.parse get(url).response.body)
  end