func main()

in packages/concatjs/devserver/main.go [30:126]
73 lines of code
15 McCabe index (conditional complexity)

func main() {
	flag.Parse()

	if len(*pkgs) == 0 || (*manifest == "") || (*scriptsManifest == "") {
		fmt.Fprintf(os.Stderr, "Required argument not set\n")
		os.Exit(1)
	}

	manifestPath, err := runfiles.Runfile(*base, *scriptsManifest)

	if err != nil {
		fmt.Fprintf(os.Stderr, "Failed to find scripts_manifest in runfiles: %v\n", err)
		os.Exit(1)
	}

	scriptFiles, err := manifestFiles(manifestPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Failed to read scripts_manifest: %v\n", err)
		os.Exit(1)
	}

	if !strings.HasPrefix(*servingPath, "/") {
		fmt.Fprintf(os.Stderr, "The specified serving_path does not start with a slash. "+
			"This causes the serving path to not have any effect.\n")
		os.Exit(1)
	}

	preScripts := make([]string, 0, 100)
	postScripts := make([]string, 0, 1)

	// Include the livereload script if IBAZEL_LIVERELOAD_URL is set.
	livereloadUrl := os.Getenv("IBAZEL_LIVERELOAD_URL")
	if livereloadUrl != "" {
		fmt.Printf("Serving livereload script from %s\n", livereloadUrl)
		livereloadLoaderSnippet := fmt.Sprintf(`(function(){
	const script = document.createElement('script');
	script.src = "%s";
	document.head.appendChild(script);
})();`, livereloadUrl)
		preScripts = append(preScripts, livereloadLoaderSnippet)
	}

	// Include the profiler script if IBAZEL_PROFILER_URL is set.
	profilerScriptURL := os.Getenv("IBAZEL_PROFILER_URL")
	if profilerScriptURL != "" {
		fmt.Printf("Serving profiler script from %s\n", profilerScriptURL)
		profilerLoaderSnippet := fmt.Sprintf(`(function(){
	const script = document.createElement('script');
	script.src = "%s";
	document.head.appendChild(script);
})();`, profilerScriptURL)
		preScripts = append(preScripts, profilerLoaderSnippet)
	}

	// Include all user scripts in preScripts. This should always include
	// the requirejs script which is added to scriptFiles by the devserver
	// skylark rule.
	for _, v := range scriptFiles {
		runfile, err := runfiles.Runfile(*base, v)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Could not find runfile %s, got error %s", v, err)
		}

		js, err := loadScript(runfile)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failed to read script %s: %v\n", v, err)
		} else {
			preScripts = append(preScripts, js)
		}
	}

	// If the entryModule is set then add a snippet to load
	// the application to postScripts to be outputted after the sources
	if *entryModule != "" {
		postScripts = append(postScripts, fmt.Sprintf("require([\"%s\"]);", *entryModule))
	}

	http.Handle(*servingPath, concatjs.ServeConcatenatedJS(*manifest, *base, preScripts, postScripts,
		&RunfileFileSystem{}))
	pkgList := strings.Split(*pkgs, ",")
	http.HandleFunc("/", devserver.CreateFileHandler(*servingPath, *manifest, pkgList, *base))

	h, err := os.Hostname()
	if err != nil {
		h = "localhost"
	}
	// Detect if we are running in a linux container inside ChromeOS
	// If so, we assume you want to use the native browser (outside the container)
	// so you'll need to modify the hostname to access the server
	if _, err := os.Stat("/etc/apt/sources.list.d/cros.list"); err == nil {
		h = h + ".linux.test"
	}

	fmt.Printf("Server listening on http://%s:%d/\n", h, *port)
	fmt.Fprintln(os.Stderr, http.ListenAndServe(fmt.Sprintf(":%d", *port), nil).Error())
	os.Exit(1)
}