rack2.rb

# frozen_string_literal: true

# Released under the MIT License.
# Copyright, 2022-2023, by Samuel Williams.

require 'console'

require_relative 'generic'
require_relative '../rewindable'

module Protocol
	module Rack
		module Adapter
			class Rack2	< Generic
				RACK_VERSION = 'rack.version'
				RACK_MULTITHREAD = 'rack.multithread'
				RACK_MULTIPROCESS = 'rack.multiprocess'
				RACK_RUN_ONCE = 'rack.run_once'
				
				RACK_IS_HIJACK = 'rack.hijack?'
				RACK_HIJACK = 'rack.hijack'
				
				def self.wrap(app)
					Rewindable.new(self.new(app))
				end
				
				def make_environment(request)
					request_path, query_string = request.path.split('?', 2)
					server_name, server_port = (request.authority || '').split(':', 2)
					
					env = {
						RACK_VERSION => [2, 0],
						RACK_MULTITHREAD => false,
						RACK_MULTIPROCESS => true,
						RACK_RUN_ONCE => false,
						
						PROTOCOL_HTTP_REQUEST => request,
						
						RACK_INPUT => Input.new(request.body),
						RACK_ERRORS => $stderr,
						RACK_LOGGER => self.logger,

						# The request protocol, either from the upgrade header or the HTTP/2 pseudo header of the same name.
						RACK_PROTOCOL => request.protocol,
						
						# The HTTP request method, such as “GET” or “POST”. This cannot ever be an empty string, and so is always required.
						CGI::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.
						CGI::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.
						CGI::PATH_INFO => request_path,
						CGI::REQUEST_PATH => request_path,
						CGI::REQUEST_URI => request.path,

						# The portion of the request URL that follows the ?, if any. May be empty, but is always required!
						CGI::QUERY_STRING => query_string || '',
						
						# The server protocol (e.g. HTTP/1.1):
						CGI::SERVER_PROTOCOL => request.version,
						
						# The request scheme:
						RACK_URL_SCHEME => request.scheme,
						
						# I'm not sure what sane defaults should be here:
						CGI::SERVER_NAME => server_name,
						CGI::SERVER_PORT => server_port,
					}
					
					self.unwrap_request(request, env)
					
					return env
				end
				
				# Build a rack `env` from the incoming request and apply it to the rack middleware.
				#
				# @parameter request [Protocol::HTTP::Request] The incoming request.
				def call(request)
					env = self.make_environment(request)
					
					status, headers, body = @app.call(env)
					
					headers, meta = self.wrap_headers(headers)
					
					# Rack 2 spec does not allow only partial hijacking.
					# if hijack_body = meta[RACK_HIJACK]
					# 	body = hijack_body
					# end
					
					return Response.wrap(env, status, headers, meta, body, request)
				rescue => exception
					Console.logger.error(self) {exception}
					
					body&.close if body.respond_to?(:close)
					
					return failure_response(exception)
				end
				
				# Process the rack response headers into into a {Protocol::HTTP::Headers} instance, along with any extra `rack.` metadata.
				# @returns [Tuple(Protocol::HTTP::Headers, Hash)]
				def wrap_headers(fields)
					headers = ::Protocol::HTTP::Headers.new
					meta = {}
					
					fields.each do |key, value|
						key = key.downcase
						
						if key.start_with?('rack.')
							meta[key] = value
						elsif value.is_a?(String)
							value.split("\n").each do |value|
								headers[key] = value
							end
						else
							headers[key] = value
						end
					end
					
					return headers, meta
				end
				
				def self.make_response(env, response)
					# These interfaces should be largely compatible:
					headers = response.headers.to_h
					
					if protocol = response.protocol
						headers['rack.protocol'] = protocol
						# headers['upgrade'] = protocol
					end
					
					if body = response.body and body.stream?
						if env[RACK_IS_HIJACK]
							headers[RACK_HIJACK] = body
							body = []
						end
					end
					
					headers.transform_values! do |value|
						value.is_a?(Array) ? value.join("\n") : value
					end
					
					[response.status, headers, body]
				end
			end
		end
	end
end