public class AppInfoParser {
    private static final Logger log = LoggerFactory.getLogger(AppInfoParser.class);
    private static final String VERSION;
    private static final String COMMIT_ID;
	    private static final String CLIENT_ID;

    protected static final String DEFAULT_VALUE = "unknown";

    static {
        Properties props = new Properties();
        try (InputStream resourceStream = AppInfoParser.class.getResourceAsStream("/kafka/kafka-version.properties")) {
            props.load(resourceStream);
        } catch (Exception e) {
            log.warn("Error while loading kafka-version.properties: {}", e.getMessage());
        }
        VERSION = props.getProperty("version", DEFAULT_VALUE).trim();
        COMMIT_ID = props.getProperty("commitId", DEFAULT_VALUE).trim();
		        CLIENT_ID = props.getProperty("clientId", DEFAULT_VALUE).trim();
    }

    public static String getVersion() {
        return VERSION;
    }

	
    public static String getCommitId() {
        return COMMIT_ID;
    }

    public static String getClientId() {
        return CLIENT_ID;
    }

    public static synchronized void registerAppInfo(String prefix, String id, Metrics metrics, long nowMs) {
        try {
            ObjectName name = new ObjectName(prefix + ":type=app-info,id=" + Sanitizer.jmxSanitize(id));
            MBeanServer server = ManagementFactory.getPlatformMBeanServer();
            if (server.isRegistered(name)) {
                log.info("The mbean of App info: [{}], id: [{}] already exists, so skipping a new mbean creation.", prefix, id);
                return;
            }
            DeprecatedAppInfo deprecatedMBean = new DeprecatedAppInfo(nowMs);
            AppInfo mBean = new AppInfo(nowMs);
            server.registerMBean(deprecatedMBean, name);
            server.registerMBean(mBean, name);

            registerMetrics(metrics, mBean); // prefix will be added later by JmxReporter
        } catch (JMException e) {
            log.warn("Error registering AppInfo mbean", e);
        }
    }

    public static synchronized void unregisterAppInfo(String prefix, String id, Metrics metrics) {
        MBeanServer server = ManagementFactory.getPlatformMBeanServer();
        try {
            ObjectName name = new ObjectName(prefix + ":type=app-info,id=" + Sanitizer.jmxSanitize(id));
            if (server.isRegistered(name))
                server.unregisterMBean(name);

            unregisterMetrics(metrics);
        } catch (JMException e) {
            log.warn("Error unregistering AppInfo mbean", e);
        } finally {
            log.info("App info {} for {} unregistered", prefix, id);
        }
    }

    private static MetricName metricName(Metrics metrics, String name) {
        return metrics.metricName(name, "app-info", "Metric indicating " + name);
    }

    private static void registerMetrics(Metrics metrics, AppInfoMBean appInfo) {
        if (metrics != null) {
            metrics.addMetric(metricName(metrics, "version"), new ImmutableValue<>(appInfo.getVersion()));
            metrics.addMetric(metricName(metrics, "commit-id"), new ImmutableValue<>(appInfo.getCommitId()));
            metrics.addMetric(metricName(metrics, "start-time-ms"), new ImmutableValue<>(appInfo.getStartTimeMs()));
            if (appInfo instanceof AppInfo) {
                metrics.addMetric(metricName(metrics, "client-id"), new ImmutableValue<>(appInfo.getClientId()));
            }
        }
    }

    private static void unregisterMetrics(Metrics metrics) {
        if (metrics != null) {
            metrics.removeMetric(metricName(metrics, "version"));
            metrics.removeMetric(metricName(metrics, "commit-id"));
            metrics.removeMetric(metricName(metrics, "start-time-ms"));
            metrics.removeMetric(metricName(metrics, "client-id"));
        }
    }

    public interface AppInfoMBean {
        String getVersion();
        String getCommitId();
        String getClientId();
        Long getStartTimeMs();
    }

    @Deprecated(since = "4.2")
    public static class DeprecatedAppInfo implements AppInfoMBean {

        private final Long startTimeMs;

        public DeprecatedAppInfo(long startTimeMs) {
            this.startTimeMs = startTimeMs;
            log.info("Kafka version: {}", AppInfoParser.getVersion());
            log.info("Kafka commitId: {}", AppInfoParser.getCommitId());
            log.info("Kafka startTimeMs: {}", startTimeMs);
        }

        @Override
        public String getVersion() {
            return AppInfoParser.getVersion();
        }

        @Override
        public String getCommitId() {
            return AppInfoParser.getCommitId();
        }

        @Override
        public String getClientId() {
            throw new UnsupportedOperationException("client-id is not implemented in DeprecatedAppInfo");
        }

        @Override
        public Long getStartTimeMs() {
            return startTimeMs;
        }

    }

    public static class AppInfo implements AppInfoMBean {

        private final Long startTimeMs;

        public AppInfo(long startTimeMs) {
            this.startTimeMs = startTimeMs;
            log.info("Kafka version: {}", AppInfoParser.getVersion());
            log.info("Kafka commitId: {}", AppInfoParser.getCommitId());
            log.info("Kafka startTimeMs: {}", startTimeMs);
            log.info("Kafka client id: {}", AppInfoParser.getClientId());
        }

        @Override
        public String getVersion() {
            return AppInfoParser.getVersion();
        }

        @Override
        public String getCommitId() {
            return AppInfoParser.getCommitId();
        }

        @Override
        public String getClientId() {
            return AppInfoParser.getClientId();
        }

        @Override
        public Long getStartTimeMs() {
            return startTimeMs;
        }

    }

    static class ImmutableValue<T> implements Gauge<T> {
        private final T value;

        public ImmutableValue(T value) {
            this.value = value;
        }

        @Override
        public T value(MetricConfig config, long now) {
            return value;
        }
    }
}