package org.ehcache.sample.config;

import io.github.jhipster.config.JHipsterProperties;

import com.codahale.metrics.JmxReporter;
import com.codahale.metrics.JvmAttributeGaugeSet;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.Slf4jReporter;
import com.codahale.metrics.health.HealthCheckRegistry;
import com.codahale.metrics.jcache.JCacheGaugeSet;
import com.codahale.metrics.jvm.*;
import com.ryantenney.metrics.spring.config.annotation.EnableMetrics;
import com.ryantenney.metrics.spring.config.annotation.MetricsConfigurerAdapter;
import com.zaxxer.hikari.HikariDataSource;
import io.prometheus.client.CollectorRegistry;
import io.prometheus.client.dropwizard.DropwizardExports;
import io.prometheus.client.exporter.MetricsServlet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.Marker;
import org.slf4j.MarkerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.web.servlet.ServletContextInitializer;
import org.springframework.cache.CacheManager;
import org.springframework.context.annotation.*;

import javax.annotation.PostConstruct;
import javax.servlet.ServletContext;
import java.lang.management.ManagementFactory;
import java.util.concurrent.TimeUnit;

@Configuration
@EnableMetrics(proxyTargetClass = true)
public class MetricsConfiguration extends MetricsConfigurerAdapter implements ServletContextInitializer {

    private static final String PROP_METRIC_REG_JVM_MEMORY = "jvm.memory";
    private static final String PROP_METRIC_REG_JVM_GARBAGE = "jvm.garbage";
    private static final String PROP_METRIC_REG_JVM_THREADS = "jvm.threads";
    private static final String PROP_METRIC_REG_JVM_FILES = "jvm.files";
    private static final String PROP_METRIC_REG_JVM_BUFFERS = "jvm.buffers";
    private static final String PROP_METRIC_REG_JVM_ATTRIBUTE_SET = "jvm.attributes";

    private static final String PROP_METRIC_REG_JCACHE_STATISTICS = "jcache.statistics";

    private final Logger log = LoggerFactory.getLogger(MetricsConfiguration.class);

    private MetricRegistry metricRegistry = new MetricRegistry();

    private HealthCheckRegistry healthCheckRegistry = new HealthCheckRegistry();

    private final JHipsterProperties jHipsterProperties;

    private HikariDataSource hikariDataSource;

    // The cacheManager is injected here to force its initialization, so the JCacheGaugeSet
    // will be correctly created below.
    public MetricsConfiguration(JHipsterProperties jHipsterProperties, CacheManager cacheManager) {
        this.jHipsterProperties = jHipsterProperties;
    }

    @Autowired(required = false)
    public void setHikariDataSource(HikariDataSource hikariDataSource) {
        this.hikariDataSource = hikariDataSource;
    }

    @Override
    @Bean
    public MetricRegistry getMetricRegistry() {
        return metricRegistry;
    }

    @Override
    @Bean
    public HealthCheckRegistry getHealthCheckRegistry() {
        return healthCheckRegistry;
    }

    @PostConstruct
    public void init() {
        log.debug("Registering JVM gauges");
        metricRegistry.register(PROP_METRIC_REG_JVM_MEMORY, new MemoryUsageGaugeSet());
        metricRegistry.register(PROP_METRIC_REG_JVM_GARBAGE, new GarbageCollectorMetricSet());
        metricRegistry.register(PROP_METRIC_REG_JVM_THREADS, new ThreadStatesGaugeSet());
        metricRegistry.register(PROP_METRIC_REG_JVM_FILES, new FileDescriptorRatioGauge());
        metricRegistry.register(PROP_METRIC_REG_JVM_BUFFERS, new BufferPoolMetricSet(ManagementFactory.getPlatformMBeanServer()));
        metricRegistry.register(PROP_METRIC_REG_JVM_ATTRIBUTE_SET, new JvmAttributeGaugeSet());
        metricRegistry.register(PROP_METRIC_REG_JCACHE_STATISTICS, new JCacheGaugeSet());
        if (hikariDataSource != null) {
            log.debug("Monitoring the datasource");
            // remove the factory created by HikariDataSourceMetricsPostProcessor until JHipster migrate to Micrometer
            hikariDataSource.setMetricsTrackerFactory(null);
            hikariDataSource.setMetricRegistry(metricRegistry);
        }
        if (jHipsterProperties.getMetrics().getJmx().isEnabled()) {
            log.debug("Initializing Metrics JMX reporting");
            JmxReporter jmxReporter = JmxReporter.forRegistry(metricRegistry).build();
            jmxReporter.start();
        }
        if (jHipsterProperties.getMetrics().getLogs().isEnabled()) {
            log.info("Initializing Metrics Log reporting");
            Marker metricsMarker = MarkerFactory.getMarker("metrics");
            final Slf4jReporter reporter = Slf4jReporter.forRegistry(metricRegistry)
                .outputTo(LoggerFactory.getLogger("metrics"))
                .markWith(metricsMarker)
                .convertRatesTo(TimeUnit.SECONDS)
                .convertDurationsTo(TimeUnit.MILLISECONDS)
                .build();
            reporter.start(jHipsterProperties.getMetrics().getLogs().getReportFrequency(), TimeUnit.SECONDS);
        }
    }

    @Override
    public void onStartup(ServletContext servletContext) {

        if (jHipsterProperties.getMetrics().getPrometheus().isEnabled()) {
            String endpoint = jHipsterProperties.getMetrics().getPrometheus().getEndpoint();

            log.debug("Initializing prometheus metrics exporting via {}", endpoint);

            CollectorRegistry.defaultRegistry.register(new DropwizardExports(metricRegistry));
            servletContext
                .addServlet("prometheusMetrics", new MetricsServlet(CollectorRegistry.defaultRegistry))
                .addMapping(endpoint);
        }
    }
}
