myronmarston/vcr

module VCR
  # @private
  module Net
    # A Net::HTTP response that has already been read raises an IOError when #read_body
    # is called with a destination string or block.
    #
    # This causes a problem when VCR records a response--it reads the body before yielding
    # the response, and if the code that is consuming the HTTP requests uses #read_body, it
    # can cause an error.
    #
    # This is a bit of a hack, but it allows a Net::HTTP response to be "re-read"
    # after it has aleady been read.  This attemps to preserve the behavior of
    # #read_body, acting just as if it had never been read.
    # @private
    module HTTPResponse
      def self.extended(response)
        response.instance_variable_set(:@__read_body_previously_called, false)
      end

      def read_body(dest = nil, &block)
        return super if @__read_body_previously_called
        return @body if dest.nil? && block.nil?
        raise ArgumentError.new("both arg and block given for HTTP method") if dest && block

        if @body
          dest ||= ::Net::ReadAdapter.new(block)
          dest << @body
          @body = dest
        end
      ensure
        # allow subsequent calls to #read_body to proceed as normal, without our hack...
        @__read_body_previously_called = true
      end
    end
  end
end