class Falcon::Adapters::Rack

def call(request)
	request_path, query_string = request.path.split('?', 2)
	server_name, server_port = (request.authority || '').split(':', 2)
	
	env = {
		RACK_VERSION => [2, 0, 0],
		
		ASYNC_HTTP_REQUEST => request,
		
		RACK_INPUT => Input.new(request.body),
		RACK_ERRORS => $stderr,
		RACK_LOGGER => Async.logger,
		
		RACK_MULTITHREAD => true,
		RACK_MULTIPROCESS => true,
		RACK_RUNONCE => false,
		
		# The HTTP request method, such as “GET” or “POST”. This cannot ever be an empty string, and so is always required.
		REQUEST_METHOD => request.method,
		
		# The initial portion of the request URL's “path” that corresponds to the application object, so that the application knows its virtual “location”. This may be an empty string, if the application corresponds to the “root” of the server.
		SCRIPT_NAME => '',
		
		# The remainder of the request URL's “path”, designating the virtual “location” of the request's target within the application. This may be an empty string, if the request URL targets the application root and does not have a trailing slash. This value may be percent-encoded when originating from a URL.
		PATH_INFO => request_path,
		REQUEST_PATH => request_path,
		REQUEST_URI => request.path,
		# The portion of the request URL that follows the ?, if any. May be empty, but is always required!
		QUERY_STRING => query_string || '',
		
		# The server protocol (e.g. HTTP/1.1):
		SERVER_PROTOCOL => request.version,
		
		# The request scheme:
		RACK_URL_SCHEME => request.scheme,
		
		# I'm not sure what sane defaults should be here:
		SERVER_NAME => server_name || '',
		SERVER_PORT => server_port || '',
	}
	
	self.unwrap_request(request, env)
	
	if request.push?
		env[RACK_EARLY_HINTS] = EarlyHints.new(request)
	end
	
	if request.hijack?
		env[RACK_IS_HIJACK] = true
		
		env[RACK_HIJACK] = lambda do
			wrapper = request.hijack
			
			# We dup this as it might be taken out of the normal control flow, and the io will be closed shortly after returning from this method.
			io = wrapper.io.dup
			wrapper.close
			
			# This is implicitly returned:
			env[RACK_HIJACK_IO] = io
		end
	else
		env[RACK_IS_HIJACK] = false
	end
	
	status, headers, body = @app.call(env)
	
	# Partial hijack is not supported/tested.
	# if hijack = headers.delete('rack.hijack')
	# 	body = Async::HTTP::Body::Writable.new
	# 
	# 	Task.current.async do
	# 		hijack.call(body)
	# 	end
	# 	return nil
	# end
	
	# if env['rack.hijack_io']
	# 	return nil
	# end
	
	return make_response(request, status, headers, body)
rescue => exception
	@logger.error "#{exception.class}: #{exception.message}\n\t#{$!.backtrace.join("\n\t")}"
	
	return failure_response(exception)
end

def failure_response(exception)
	Async::HTTP::Response.for_exception(exception)
end

def initialize(app, logger = Async.logger)
	@app = app
	
	raise ArgumentError, "App must be callable!" unless @app.respond_to?(:call)
	
	@logger = logger
end

def make_response(request, status, headers, body)
	# @logger.debug(request) {"Rack response: #{status} #{headers.inspect} #{body.class}"}
	
	return Response.wrap(status, headers, body)
end

def unwrap_headers(headers, env)
	headers.each do |key, value|
		http_key = "HTTP_#{key.upcase.tr('-', '_')}"
		
		if current_value = env[http_key]
			env[http_key] = "#{current_value}\n#{value}"
		else
			env[http_key] = value
		end
	end
end

def unwrap_request(request, env)
	if content_type = request.headers.delete('content-type')
		env[CONTENT_TYPE] = content_type
	end
	
	# In some situations we don't know the content length, e.g. when using chunked encoding, or when decompressing the body.
	if body = request.body and length = body.length
		env[CONTENT_LENGTH] = length.to_s
	end
	
	self.unwrap_headers(request.headers, env)
	
	# HTTP/2 prefers `:authority` over `host`, so we do this for backwards compatibility.
	env[HTTP_HOST] ||= request.authority
	
	# This is the HTTP/1 header for the scheme of the request and is used by Rack.
	# Technically it should use the Forwarded header but this is not common yet.
	# https://tools.ietf.org/html/rfc7239#section-5.4
	# https://github.com/rack/rack/issues/1310
	env[HTTP_X_FORWARDED_PROTO] ||= request.scheme
	
	if remote_address = request.remote_address
		env[REMOTE_ADDR] = remote_address.ip_address if remote_address.ip?
	end
end