package com.vlkan;

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import com.zaxxer.hikari.metrics.prometheus.PrometheusMetricsTrackerFactory;
import io.micrometer.core.instrument.Clock;
import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.prometheus.PrometheusConfig;
import io.micrometer.prometheus.PrometheusMeterRegistry;
import io.prometheus.client.CollectorRegistry;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Random;

public enum HikaricpMicrometerBug {;

    public static void main(String[] args) throws SQLException {

        // Tickle HikariCP and feed statistics to a MeterRegistry.
        PrometheusMeterRegistry meterRegistry1 = new PrometheusMeterRegistry(PrometheusConfig.DEFAULT);
        tickleStatistics(meterRegistry1);
        scrapeStatistics(meterRegistry1);

        /*
         * hitCount: 1825
         * hikaricp_connections_acquire_seconds_count{pool="test",} 1.0
         * hikaricp_connections_acquire_seconds_sum{pool="test",} 8.0015E-5
         * hikaricp_connections_acquire_seconds_max{pool="test",} 8.0015E-5
         * hikaricp_connections{pool="test",} 0.0
         * hikaricp_connections_usage_seconds_count{pool="test",} 1.0
         * hikaricp_connections_usage_seconds_sum{pool="test",} 1.083
         * hikaricp_connections_usage_seconds_max{pool="test",} 1.083
         * hikaricp_connections_creation_seconds_max{pool="test",} 0.0
         * hikaricp_connections_creation_seconds_count{pool="test",} 0.0
         * hikaricp_connections_creation_seconds_sum{pool="test",} 0.0
         * hikaricp_connections_active{pool="test",} 0.0
         * hikaricp_connections_timeout_total{pool="test",} 0.0
         * hikaricp_connections_idle{pool="test",} 0.0
         * hikaricp_connections_pending{pool="test",} 0.0
         * hikaricp_connections_min{pool="test",} 1.0
         * hikaricp_connections_max{pool="test",} 1.0
         */

        // Tickle HikariCP and feed statistics to a CollectorRegistry.
        CollectorRegistry collectorRegistry = new CollectorRegistry();
        PrometheusMeterRegistry meterRegistry2 = new PrometheusMeterRegistry(PrometheusConfig.DEFAULT, collectorRegistry, Clock.SYSTEM);
        tickleStatistics(collectorRegistry);
        scrapeStatistics(meterRegistry2);

        /*
         * hitCount: 1825
         * hikaricp_active_connections{pool="test",} 0.0
         * hikaricp_idle_connections{pool="test",} 0.0
         * hikaricp_pending_threads{pool="test",} 0.0
         * hikaricp_connections{pool="test",} 0.0
         * hikaricp_max_connections{pool="test",} 1.0
         * hikaricp_min_connections{pool="test",} 1.0
         * hikaricp_connection_creation_millis{pool="test",quantile="0.5",} NaN
         * hikaricp_connection_creation_millis{pool="test",quantile="0.95",} NaN
         * hikaricp_connection_creation_millis{pool="test",quantile="0.99",} NaN
         * hikaricp_connection_creation_millis_count{pool="test",} 0.0
         * hikaricp_connection_creation_millis_sum{pool="test",} 0.0
         * hikaricp_connection_acquired_nanos{pool="test",quantile="0.5",} 17965.0
         * hikaricp_connection_acquired_nanos{pool="test",quantile="0.95",} 17965.0
         * hikaricp_connection_acquired_nanos{pool="test",quantile="0.99",} 17965.0
         * hikaricp_connection_acquired_nanos_count{pool="test",} 1.0
         * hikaricp_connection_acquired_nanos_sum{pool="test",} 17965.0
         * hikaricp_connection_usage_millis{pool="test",quantile="0.5",} 678.0
         * hikaricp_connection_usage_millis{pool="test",quantile="0.95",} 678.0
         * hikaricp_connection_usage_millis{pool="test",quantile="0.99",} 678.0
         * hikaricp_connection_usage_millis_count{pool="test",} 1.0
         * hikaricp_connection_usage_millis_sum{pool="test",} 678.0
         * hikaricp_connection_timeout_total{pool="test",} 0.0
         */

    }

    private static void tickleStatistics(Object meterOrCollectorRegistry) throws SQLException {
        try (HikariDataSource dataSource = createHikariDataSource(meterOrCollectorRegistry)) {
            try (Connection connection = dataSource.getConnection()) {

                // Create table.
                try (PreparedStatement statement = connection.prepareStatement("CREATE TABLE number (value INTEGER)")) {
                    statement.execute();
                }

                // Populate numbers.
                Random random = new Random(0);
                int maxNumber = 5_000;
                int numberCount = 1_000;
                try (PreparedStatement statement = connection.prepareStatement("INSERT INTO number (value) VALUES (?)")) {
                    for (int numberIndex = 0; numberIndex < numberCount; numberIndex++) {
                        int number = random.nextInt(maxNumber);
                        statement.setInt(1, number);
                        statement.addBatch();
                    }
                    statement.executeBatch();
                }

                // Query numbers.
                int queryCount = 10_000;
                int hitCount = 0;
                for (int queryIndex = 0; queryIndex < queryCount; queryIndex++) {
                    int number = random.nextInt(maxNumber);
                    try (PreparedStatement statement = connection.prepareStatement("SELECT 1 FROM number WHERE value = ? LIMIT 1")) {
                        statement.setInt(1, number);
                        try (ResultSet resultSet = statement.executeQuery()) {
                            if (resultSet.next()) {
                                hitCount++;
                            }
                        }
                    }
                }
                System.out.format("hitCount: %d%n", hitCount);

                // Commit changes.
                connection.commit();

            }
        }
    }

    private static HikariDataSource createHikariDataSource(Object meterOrCollectorRegistry) {
        HikariConfig hikariConfig = createHikariConfig(meterOrCollectorRegistry);
        return new HikariDataSource(hikariConfig);
    }

    private static HikariConfig createHikariConfig(Object meterOrCollectorRegistry) {

        // Create base HikariCP configuration.
        HikariConfig hikariConfig = new HikariConfig();
        hikariConfig.setPoolName("test");
        hikariConfig.setDriverClassName("org.h2.Driver");
        hikariConfig.setJdbcUrl("jdbc:h2:mem:test");
        hikariConfig.setUsername("sa");
        hikariConfig.setPassword("");
        hikariConfig.setAutoCommit(false);
        hikariConfig.setMinimumIdle(1);
        hikariConfig.setMaximumPoolSize(1);
        hikariConfig.setConnectionTimeout(1_000L);
        hikariConfig.setMaxLifetime(30_000L);
        hikariConfig.setInitializationFailTimeout(1_000L);

        // Set metrics.
        if (meterOrCollectorRegistry instanceof MeterRegistry) {
            MeterRegistry meterRegistry = (MeterRegistry) meterOrCollectorRegistry;
            hikariConfig.setMetricRegistry(meterRegistry);
        } else {
            CollectorRegistry collectorRegistry = (CollectorRegistry) meterOrCollectorRegistry;
            PrometheusMetricsTrackerFactory metricsTrackerFactory = new PrometheusMetricsTrackerFactory(collectorRegistry);
            hikariConfig.setMetricsTrackerFactory(metricsTrackerFactory);
        }
        return hikariConfig;

    }

    private static void scrapeStatistics(PrometheusMeterRegistry meterRegistry) {
        meterRegistry
                .scrape()
                .lines()
                .filter(line -> !line.startsWith("#"))
                .forEach(System.out::println);
        System.out.println();
    }

}