class Excon::Middleware::Idempotent

def self.valid_parameter_keys
  [
    :idempotent,
    :retries_remaining,
    :retry_errors,
    :retry_interval,
    :retry_limit
  ]
end

def error_call(datum)
  if datum[:idempotent]
    if datum.has_key?(:request_block)
      if datum[:request_block].respond_to?(:rewind)
        datum[:request_block].rewind
      else
        Excon.display_warning('Excon requests with a :request_block must implement #rewind in order to be :idempotent.')
        datum[:idempotent] = false
      end
    end
    if datum.has_key?(:response_block) && datum[:response_block].respond_to?(:rewind)
      datum[:response_block].rewind
    end
    if datum.has_key?(:pipeline)
      Excon.display_warning("Excon requests can not be :idempotent when pipelining.")
      datum[:idempotent] = false
    end
  end
  if datum[:idempotent] && datum[:retry_errors].any? {|ex| datum[:error].kind_of?(ex) } && datum[:retries_remaining] > 1
    sleep(datum[:retry_interval]) if datum[:retry_interval]
    # reduces remaining retries, reset connection, and restart request_call
    datum[:retries_remaining] -= 1
    connection = datum.delete(:connection)
    valid_keys = Set.new(connection.valid_request_keys(datum[:middlewares]))
    datum.select! {|key, _| valid_keys.include?(key) }
    connection.request(datum)
  else
    @stack.error_call(datum)
  end
end

def request_call(datum)
  datum[:retries_remaining] ||= datum[:retry_limit]
  @stack.request_call(datum)
end