func NewBuilder()

in spark/client/channel/channel.go [151:235]
67 lines of code
20 McCabe index (conditional complexity)

func NewBuilder(connection string) (*BaseBuilder, error) {
	u, err := url.Parse(connection)
	if err != nil {
		return nil, err
	}

	if u.Hostname() == "" {
		return nil, sparkerrors.WithType(errors.New("URL must contain a hostname"), sparkerrors.InvalidInputError)
	}

	if u.Scheme != "sc" {
		return nil, sparkerrors.WithType(errors.New("URL schema must be set to `sc`"), sparkerrors.InvalidInputError)
	}

	port := 15002
	host := u.Host
	// Check if the host part of the URL contains a port and extract.
	if strings.Contains(u.Host, ":") {
		// We can ignore the error here already since the url parsing
		// raises the error about invalid port.
		hostStr, portStr, _ := net.SplitHostPort(u.Host)
		host = hostStr
		if len(portStr) != 0 {
			port, err = strconv.Atoi(portStr)
			if err != nil {
				return nil, err
			}
		}
	}

	// Validate that the URL path is empty or follows the right format.
	if u.Path != "" && !strings.HasPrefix(u.Path, "/;") {
		return nil, sparkerrors.WithType(
			fmt.Errorf("the URL path (%v) must be empty or have a proper parameter syntax", u.Path),
			sparkerrors.InvalidInputError)
	}

	cb := &BaseBuilder{
		host:      host,
		port:      port,
		headers:   map[string]string{},
		sessionId: uuid.NewString(),
		userAgent: "",
	}

	elements := strings.Split(u.Path, ";")
	for _, e := range elements {
		props := strings.Split(e, "=")
		if len(props) == 2 {
			if props[0] == "token" {
				cb.token = props[1]
			} else if props[0] == "user_id" {
				cb.user = props[1]
			} else if props[0] == "session_id" {
				cb.sessionId = props[1]
			} else if props[0] == "user_agent" {
				cb.userAgent = props[1]
			} else {
				cb.headers[props[0]] = props[1]
			}
		}
	}

	// Set default user ID if not set.
	if cb.user == "" {
		cb.user = os.Getenv("USER")
		if cb.user == "" {
			cb.user = "na"
		}
	}

	// Update the user agent if it is not set or set to a custom value.
	val := os.Getenv("SPARK_CONNECT_USER_AGENT")
	if cb.userAgent == "" && val != "" {
		cb.userAgent = os.Getenv("SPARK_CONNECT_USER_AGENT")
	} else if cb.userAgent == "" {
		cb.userAgent = "_SPARK_CONNECT_GO"
	}

	// In addition, to the specified user agent, we need to append information about the
	// host encoded as user agent components.
	cb.userAgent = fmt.Sprintf("%s spark/%s os/%s go/%s", cb.userAgent, spark.Version(), runtime.GOOS, runtime.Version())

	return cb, nil
}