module RailsConnector
  class ConnectionManager
    SOCKET_ERRORS = [
      EOFError,
      Errno::ECONNABORTED,
      Errno::ECONNREFUSED,
      Errno::ECONNRESET,
      Errno::EINVAL,
      Errno::EPIPE,
      Errno::ETIMEDOUT,
      IOError,
      SocketError,
      Timeout::Error,
    ].freeze

    DEFAULT_TIMEOUT = 10.freeze

    attr_reader :uri

    def initialize(uri)
      @uri = uri
    end

    def request(request, timeout=DEFAULT_TIMEOUT)
      request['User-Agent'] = user_agent

      retry_once_and_reset_connection do
        ensure_started(uri, timeout)
        connection.request(request)
      end
    end

    private

    attr_accessor :connection

    def ensure_started(uri, timeout=DEFAULT_TIMEOUT)
      if @connection && @connection.started?
        configure_timeout(@connection, timeout)
      else
        conn = Net::HTTP.new(uri.host, uri.port)
        if uri.scheme == 'https'
          conn.use_ssl = true
          conn.verify_mode = OpenSSL::SSL::VERIFY_PEER
          conn.ca_file = RailsConnector::Configuration.ca_file
        end
        configure_timeout(conn, timeout)
        retry_twice_on_socket_error do
          conn.start
        end
        @connection = conn
      end
    end

    def ensure_finished
      @connection.finish if @connection && @connection.started?
      @connection = nil
    end

    def retry_once_and_reset_connection
      retried = false
      begin
        yield
      rescue *SOCKET_ERRORS => e
        raise NetworkError.from_socket_error(e) if retried
        ensure_finished
        retried = true
        retry
      end
    end

    def retry_twice_on_socket_error
      attempt = 0
      begin
        yield
      rescue *SOCKET_ERRORS => e
        raise NetworkError.from_socket_error(e) if attempt == 2
        attempt += 1
        retry
      end
    end

    def configure_timeout(connection, timeout)
      connection.open_timeout = timeout
      connection.read_timeout = timeout
      connection.ssl_timeout = timeout
    end

    def user_agent
      @user_agent ||= (
        gem_info = Gem.loaded_specs["infopark_cloud_connector"]
        if gem_info
          "#{gem_info.name}-#{gem_info.version}"
        end
      )
    end
  end
end