function _createConnection()

in server/src/node/main.ts [188:261]
71 lines of code
19 McCabe index (conditional complexity)

function _createConnection<PConsole = _, PTracer = _, PTelemetry = _, PClient = _, PWindow = _, PWorkspace = _, PLanguages = _, PNotebooks = _>(
	input?: NodeJS.ReadableStream | MessageReader, output?: NodeJS.WritableStream | MessageWriter,
	options?: ConnectionStrategy | ConnectionOptions,
	factories?: Features<PConsole, PTracer, PTelemetry, PClient, PWindow, PWorkspace, PLanguages, PNotebooks>,
): _Connection<PConsole, PTracer, PTelemetry, PClient, PWindow, PWorkspace, PLanguages, PNotebooks> {
	if (!input && !output && process.argv.length > 2) {
		let port: number | undefined = void 0;
		let pipeName: string | undefined = void 0;
		let argv = process.argv.slice(2);
		for (let i = 0; i < argv.length; i++) {
			let arg = argv[i];
			if (arg === '--node-ipc') {
				input = new IPCMessageReader(process);
				output = new IPCMessageWriter(process);
				break;
			} else if (arg === '--stdio') {
				input = process.stdin;
				output = process.stdout;
				break;
			} else if (arg === '--socket') {
				port = parseInt(argv[i + 1]);
				break;
			} else if (arg === '--pipe') {
				pipeName = argv[i + 1];
				break;
			}
			else {
				var args = arg.split('=');
				if (args[0] === '--socket') {
					port = parseInt(args[1]);
					break;
				} else if (args[0] === '--pipe') {
					pipeName = args[1];
					break;
				}
			}
		}
		if (port) {
			let transport = createServerSocketTransport(port);
			input = transport[0];
			output = transport[1];
		} else if (pipeName) {
			let transport = createServerPipeTransport(pipeName);
			input = transport[0];
			output = transport[1];
		}
	}
	var commandLineMessage = 'Use arguments of createConnection or set command line parameters: \'--node-ipc\', \'--stdio\' or \'--socket={number}\'';
	if (!input) {
		throw new Error('Connection input stream is not set. ' + commandLineMessage);
	}
	if (!output) {
		throw new Error('Connection output stream is not set. ' + commandLineMessage);
	}

	// Backwards compatibility
	if (Is.func((input as NodeJS.ReadableStream).read) && Is.func((input as NodeJS.ReadableStream).on)) {
		let inputStream = <NodeJS.ReadableStream>input;
		inputStream.on('end', () => {
			endProtocolConnection();
			process.exit(_shutdownReceived ? 0 : 1);
		});
		inputStream.on('close', () => {
			endProtocolConnection();
			process.exit(_shutdownReceived ? 0 : 1);
		});
	}

	const connectionFactory = (logger: Logger): ProtocolConnection => {
		const result = createProtocolConnection(input as any, output as any, logger, options);
		return result;
	};
	return createCommonConnection(connectionFactory, watchDog, factories);
}