module Async::HTTP::Cache::Body

def self.wrap(response, &block)
	if body = response.body
		if body.empty?
			# A body that is empty? at the outset, is immutable. This generally only applies to HEAD requests.
			yield response, body
		else
			# Insert a rewindable body so that we can cache the response body:
			rewindable = ::Protocol::HTTP::Body::Rewindable.wrap(response)
			
			unless response.headers.include?(ETAG)
				# Compute a digest and add it to the response headers:
				::Protocol::HTTP::Body::Digestable.wrap(response) do |wrapper|
					response.headers.add(ETAG, wrapper.etag)
				end
				
				# Ensure the etag is listed as a trailer:
				response.headers.add(TRAILER, ETAG)
			end
			
			# Wrap the response with the callback:
			::Protocol::HTTP::Body::Completable.wrap(response) do |error|
				if error
					Console::Event::Failure.for(error).emit(self)
				else
					yield response, rewindable.buffered
				end
			end
		end
	else
		yield response, nil
	end
	
	return response
end