module Protocol::Rack::Body

def self.completion_callback(response_finished, env, status, headers)
	proc do |error|
		response_finished.each do |callback|
			callback.call(env, status, headers, error)
		end
	end
end

def self.wrap(env, status, headers, body, input = nil)
	# In no circumstance do we want this header propagating out:
	if length = headers.delete(CONTENT_LENGTH)
		# We don't really trust the user to provide the right length to the transport.
		length = Integer(length)
	end
	
	# If we have an Async::HTTP body, we return it directly:
	if body.is_a?(::Protocol::HTTP::Body::Readable)
		# Ignore.
	elsif status == 200 and body.respond_to?(:to_path)
		begin
			# Don't mangle partial responses (206)
			body = ::Protocol::HTTP::Body::File.open(body.to_path).tap do
				body.close if body.respond_to?(:close) # Close the original body.
			end
		rescue Errno::ENOENT
			# If the file is not available, ignore.
		end
	elsif body.respond_to?(:each)
		body = Body::Enumerable.wrap(body, length)
	else
		body = Body::Streaming.new(body, input)
	end
	
	if response_finished = env[RACK_RESPONSE_FINISHED] and response_finished.any?
		body = ::Protocol::HTTP::Body::Completable.new(body, completion_callback(response_finished, env, status, headers))
	end
	
	return body
end