env

var ValidateDirPath = func(path string) error {
	_, err := os.ReadDir(path)
	if err != nil {
		return err
	}
	return nil
}

var ValidateGreaterThanOrEqualToZero = func(v int) error {
	if v < 0 {
		return fmt.Errorf("must be greater than or equal to 0: %d", v)
	}
	return nil
}

var ValidateGreaterThanZero = func(v int) error {
	if v < 1 {
		return fmt.Errorf("must be greater than 0: %d", v)
	}
	return nil
}

var ValidateHost = func(host string) error {
	if host == "" {
		return errors.New("host cannot be empty")
	}

	h, portStr, err := net.SplitHostPort(host)
	if err == nil {

		port, convErr := strconv.Atoi(portStr)
		if convErr != nil {
			return fmt.Errorf("invalid port %q: %w", portStr, convErr)
		}

		if portErr := ValidatePort(port); portErr != nil {
			return fmt.Errorf("invalid port: %w", portErr)
		}

		host = h
	}

	if net.ParseIP(host) != nil {
		return nil
	}

	return ValidateHostname(host)
}

var ValidatePort = func(v int) error {
	if v < 1000 || v > 65535 {
		return fmt.Errorf("must be between 1000 and 65535: %d", v)
	}
	return nil
}