class Protocol::Rack::Adapter::Rack2

It handles the conversion between {Protocol::HTTP} and Rack 2 environments.
The Rack 2 adapter provides compatibility with Rack 2.x applications.

def self.make_response(env, response)

@returns [Tuple(Integer, Hash, Object)] The Rack 2 response tuple [status, headers, body].
@parameter response [Protocol::HTTP::Response] The HTTP response.
@parameter env [Hash] The rack environment.

Handles protocol upgrades and streaming responses.
Convert a {Protocol::HTTP::Response} into a Rack 2 response tuple. 
def self.make_response(env, response)
	# These interfaces should be largely compatible:
	headers = response.headers.to_h
	
	self.extract_protocol(env, response, headers)
	
	if body = response.body and body.stream?
		if env[RACK_IS_HIJACK]
			headers[RACK_HIJACK] = body
			body = []
		end
	end
	
	headers.transform_values! do |value|
		if value.is_a?(Array)
			value.join("\n")
		else
			value
		end
	end
	
	[response.status, headers, body]
end

def call(request)

@raises [ArgumentError] If the status is not an integer or headers are nil.
@returns [Protocol::HTTP::Response] The HTTP response.
@parameter request [Protocol::HTTP::Request] The incoming request.

Build a rack `env` from the incoming request and apply it to the rack middleware. 
def call(request)
	env = self.make_environment(request)
	
	status, headers, body = @app.call(env)
	
	if status
		status = status.to_i
	else
		raise ArgumentError, "Status must be an integer!"
	end
	
	unless headers
		raise ArgumentError, "Headers must not be nil!"
	end
	
	# unless body.respond_to?(:each)
	# 	raise ArgumentError, "Body must respond to #each!"
	# end
	
	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.error(self, exception)
	
	body&.close if body.respond_to?(:close)
	
	return failure_response(exception)
end

def make_environment(request)

@returns [Hash] The Rack 2 environment hash.
@parameter request [Protocol::HTTP::Request] The incoming request.

Sets up all required Rack 2 environment variables and processes the request.
Create a Rack 2 environment hash for the request. 
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 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,
	}
	# SERVER_PORT is optional but must not be set if it is not present.
	if server_port
		env[CGI::SERVER_PORT] = server_port
	end
	
	self.unwrap_request(request, env)
	
	return env
end

def wrap_headers(fields)

@returns [Tuple(Protocol::HTTP::Headers, Hash)] The processed headers and metadata.
@parameter fields [Hash] The raw response headers.

Headers with newline-separated values are split into multiple headers.
Process the rack response headers into a {Protocol::HTTP::Headers} instance, along with any extra `rack.` metadata. 
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