'use strict';
const {isIP} = require('net');
const assert = require('assert');

const getHost = host => {
	if (host[0] === '[') {
		const idx = host.indexOf(']');

		assert(idx !== -1);
		return host.slice(1, idx);
	}

	const idx = host.indexOf(':');
	if (idx === -1) {
		return host;
	}

	return host.slice(0, idx);
};

module.exports = host => {
	const servername = getHost(host);

	if (isIP(servername)) {
		return '';
	}

	return servername;
};