protected String resolveWelcomeBanner()

in sshd-core/src/main/java/org/apache/sshd/server/session/ServerUserAuthService.java [521:585]
55 lines of code
17 McCabe index (conditional complexity)

    protected String resolveWelcomeBanner(ServerSession session) throws IOException {
        Object bannerValue = CoreModuleProperties.WELCOME_BANNER.getOrNull(this);
        if (bannerValue == null) {
            return null;
        }

        if (bannerValue instanceof CharSequence) {
            String message = bannerValue.toString();
            if (GenericUtils.isEmpty(message)) {
                return null;
            }

            if (CoreModuleProperties.AUTO_WELCOME_BANNER_VALUE.equalsIgnoreCase(message)) {
                try {
                    return KeyRandomArt.combine(session, ' ', session.getKeyPairProvider());
                } catch (IOException e) {
                    throw e;
                } catch (Exception e) {
                    throw new IOException(e);
                }
            }

            if (!message.contains("://")) {
                return message;
            }

            try {
                bannerValue = new URI(message);
            } catch (URISyntaxException e) {
                log.error("resolveWelcomeBanner({}) bad path URI {}: {}", session, message, e.getMessage());
                throw new MalformedURLException(
                        e.getClass().getSimpleName() + " - bad URI (" + message + "): " + e.getMessage());
            }

            if (message.startsWith("file:/")) {
                bannerValue = Paths.get((URI) bannerValue);
            }
        }

        if (bannerValue instanceof File) {
            bannerValue = ((File) bannerValue).toPath();
        }

        if (bannerValue instanceof Path) {
            Path path = (Path) bannerValue;
            if ((!Files.exists(path)) || (Files.size(path) <= 0L)) {
                if (log.isDebugEnabled()) {
                    log.debug("resolveWelcomeBanner({}) file is empty/does not exist {}", session, path);
                }
                return null;
            }
            bannerValue = path.toUri();
        }

        if (bannerValue instanceof URI) {
            bannerValue = ((URI) bannerValue).toURL();
        }

        if (bannerValue instanceof URL) {
            Charset cs = CoreModuleProperties.WELCOME_BANNER_CHARSET.getRequired(this);
            return loadWelcomeBanner(session, (URL) bannerValue, cs);
        }

        return bannerValue.toString();
    }