class Falcon::Adapters::Rack

def call(request, peer: nil, address: nil)
	request_path, query_string = request.path.split('?', 2)
	server_name, server_port = (request.authority || '').split(':', 2)
	
	env = {
		'rack.version' => [2, 0, 0],
		
		'rack.input' => Input.new(request.body),
		'rack.errors' => $stderr,
		
		'rack.multithread' => true,
		'rack.multiprocess' => true,
		'rack.run_once' => 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,
		
		# 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,
		'rack.url_scheme' => 'http',
		
		# I'm not sure what sane defaults should be here:
		'SERVER_NAME' => server_name || '',
		'SERVER_PORT' => server_port || '',
	}
	
	if content_type = request.headers.delete('content-type')
		env['CONTENT_TYPE'] = content_type
	end
	
	if content_length = request.headers.delete('content-length')
		env['CONTENT_LENGTH'] = content_length
	end
	
	request.headers.each do |key, value|
		env["HTTP_#{key.upcase.tr('-', '_')}"] = value
	end
	
	if peer
		env['rack.hijack?'] = true
		env['rack.hijack'] = lambda do
			env['rack.hijack_io'] = peer
		end
		
		if remote_address = peer.remote_address
			env['REMOTE_ADDR'] = remote_address.ip_address if remote_address.ip?
		end
	end
	
	status, headers, body = @app.call(env)
	
	if env['rack.hijack_io']
		throw :hijack
	else
		# We normalize headers to be lower case.
		headers = headers.map{|key, value| [key.downcase, value]}.to_h
		
		return Async::HTTP::Response[status, headers, Async::HTTP::Body::Buffered.wrap(body)]
	end
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
	@logger = logger
end