function useProxySettings()

in src/index.ts [125:200]
67 lines of code
17 McCabe index (conditional complexity)

	function useProxySettings(useHostProxy: boolean, useProxySettings: boolean, req: http.ClientRequest, opts: http.RequestOptions, url: string, stackText: string, callback: (proxy?: string) => void) {

		if (!useProxySettings) {
			callback('DIRECT');
			return;
		}

		const parsedUrl = nodeurl.parse(url); // Coming from Node's URL, sticking with that.

		const hostname = parsedUrl.hostname;
		if (hostname === 'localhost' || hostname === '127.0.0.1' || hostname === '::1' || hostname === '::ffff:127.0.0.1') {
			localhostCount++;
			callback('DIRECT');
			log(LogLevel.Debug, 'ProxyResolver#resolveProxy localhost', url, 'DIRECT', stackText);
			return;
		}

		const { secureEndpoint } = opts as any;
		const defaultPort = secureEndpoint ? 443 : 80;
		if (typeof hostname === 'string' && envNoProxy(hostname, String(parsedUrl.port || defaultPort))) {
			envNoProxyCount++;
			callback('DIRECT');
			log(LogLevel.Debug, 'ProxyResolver#resolveProxy envNoProxy', url, 'DIRECT', stackText);
			return;
		}

		let settingsProxy = proxyFromConfigURL(getHttpProxySetting());
		if (settingsProxy) {
			settingsCount++;
			callback(settingsProxy);
			log(LogLevel.Debug, 'ProxyResolver#resolveProxy settings', url, settingsProxy, stackText);
			return;
		}

		if (envProxy) {
			envCount++;
			callback(envProxy);
			log(LogLevel.Debug, 'ProxyResolver#resolveProxy env', url, envProxy, stackText);
			return;
		}

		const key = getCacheKey(parsedUrl);
		const proxy = getCachedProxy(key);
		if (proxy) {
			cacheCount++;
			collectResult(results, proxy, parsedUrl.protocol === 'https:' ? 'HTTPS' : 'HTTP', req);
			callback(proxy);
			log(LogLevel.Debug, 'ProxyResolver#resolveProxy cached', url, proxy, stackText);
			return;
		}

		if (!useHostProxy) {
			callback('DIRECT');
			log(LogLevel.Debug, 'ProxyResolver#resolveProxy unconfigured', url, 'DIRECT', stackText);
			return;
		}

		const start = Date.now();
		params.resolveProxy(url) // Use full URL to ensure it is an actually used one.
			.then(proxy => {
				if (proxy) {
					cacheProxy(key, proxy);
					collectResult(results, proxy, parsedUrl.protocol === 'https:' ? 'HTTPS' : 'HTTP', req);
				}
				callback(proxy);
				log(LogLevel.Debug, 'ProxyResolver#resolveProxy', url, proxy, stackText);
			}).then(() => {
				count++;
				duration = Date.now() - start + duration;
			}, err => {
				errorCount++;
				const fallback: string | undefined = cache.values().next().value; // fall back to any proxy (https://github.com/microsoft/vscode/issues/122825)
				callback(fallback);
				log(LogLevel.Error, 'ProxyResolver#resolveProxy', fallback, toErrorMessage(err), stackText);
			});
	}