class Protocol::Rack::Adapter::Rack3

Unlike Rack 2, this adapter supports streaming responses and has a simpler environment setup.
It handles the conversion between {Protocol::HTTP} and Rack 3 environments.
The Rack 3 adapter provides compatibility with Rack 3.x applications.

def self.make_response(env, response)

@returns [Tuple(Integer, Hash, Object)] The Rack 3 response tuple [status, headers, body].
@parameter response [Protocol::HTTP::Response] The HTTP response.
@parameter env [Hash] The rack environment.

Unlike Rack 2, this adapter forces streaming responses by converting the body to a callable.
Handles protocol upgrades and streaming responses.
Convert a {Protocol::HTTP::Response} into a Rack 3 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?
		# Force streaming response:
		body = body.method(:call)
	end
	
	[response.status, headers, body]
end

def self.parse_file(...)

@returns [Interface(:call)] The Rack application.
@parameter path [String] The path to the Rackup file.

Uses the Rack 3.x interface for parsing Rackup files.
Parses a Rackup file and returns the application. 
def self.parse_file(...)
	::Rack::Builder.parse_file(...)
end

def self.wrap(app)

@returns [Rack3] A new adapter instance.
@parameter app [Interface(:call)] A Rack application.

Unlike Rack 2, this adapter doesn't require a {Rewindable} wrapper.
Creates a new adapter instance for the given Rack application. 
def self.wrap(app)
	self.new(app)
end

def make_environment(request)

@returns [Hash] The Rack 3 environment hash.
@parameter request [Protocol::HTTP::Request] The incoming request.

Unlike Rack 2, this adapter doesn't set Rack version or threading flags.
Sets up all required Rack 3 environment variables and processes the request.
Create a Rack 3 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 = {
		PROTOCOL_HTTP_REQUEST => request,
		
		RACK_INPUT => Input.new(request.body),
		RACK_ERRORS => $stderr,
		RACK_LOGGER => self.logger,
		
		# The response finished callbacks:
		RACK_RESPONSE_FINISHED => [],
		
		# 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.

Unlike Rack 2, this adapter handles array values directly without splitting on newlines.
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?(Array)
			value.each do |value|
				headers[key] = value
			end
		else
			headers[key] = value
		end
	end
	
	return headers, meta
end