class Protocol::HTTP::ContentEncoding

def call(request)
	response = super
	
	# Early exit if the response has already specified a content-encoding.
	return response if response.headers["content-encoding"]
	
	# This is a very tricky issue, so we avoid it entirely.
	# https://lists.w3.org/Archives/Public/ietf-http-wg/2014JanMar/1179.html
	return response if response.partial?
	
	# Ensure that caches are aware we are varying the response based on the accept-encoding request header:
	response.headers.add("vary", "accept-encoding")
	
	# TODO use http-accept and sort by priority
	if !response.body.empty? and accept_encoding = request.headers["accept-encoding"]
		
		if content_type = response.headers["content-type"] and @content_types =~ content_type
			body = response.body
			
			accept_encoding.each do |name|
				if wrapper = @wrappers[name]
					response.headers["content-encoding"] = name
					
					body = wrapper.call(body)
					
					break
				end
			end
			
			response.body = body
		end
	end
	
	return response
end

def initialize(app, content_types = DEFAULT_CONTENT_TYPES, wrappers = DEFAULT_WRAPPERS)
	super(app)
	
	@content_types = content_types
	@wrappers = wrappers
end