/*
 * Copyright The OpenTelemetry Authors
 * SPDX-License-Identifier: Apache-2.0
 */

package io.opentelemetry.instrumentation.apachedbcp.v2_0;

import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.api.common.Attributes;
import io.opentelemetry.api.metrics.BatchCallback;
import io.opentelemetry.api.metrics.ObservableLongMeasurement;
import io.opentelemetry.instrumentation.api.metrics.db.DbConnectionPoolMetrics;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.commons.dbcp2.BasicDataSourceMXBean;

final class DataSourceMetrics {
  private static final String INSTRUMENTATION_NAME = "io.opentelemetry.apache-dbcp-2.0";

  // a weak map does not make sense here because each Meter holds a reference to the dataSource
  // all instrumented/known implementations of BasicDataSourceMXBean do not implement
  // equals()/hashCode(), so it's safe to keep them in a plain ConcurrentHashMap
  private static final Map<BasicDataSourceMXBean, BatchCallback> dataSourceMetrics =
      new ConcurrentHashMap<>();

  public static void registerMetrics(
      OpenTelemetry openTelemetry, BasicDataSourceMXBean dataSource, String dataSourceName) {
    DbConnectionPoolMetrics metrics =
        DbConnectionPoolMetrics.create(openTelemetry, INSTRUMENTATION_NAME, dataSourceName);

    ObservableLongMeasurement connections = metrics.connections();
    ObservableLongMeasurement minIdleConnections = metrics.minIdleConnections();
    ObservableLongMeasurement maxIdleConnections = metrics.maxIdleConnections();
    ObservableLongMeasurement maxConnections = metrics.maxConnections();

    Attributes attributes = metrics.getAttributes();
    Attributes usedConnectionsAttributes = metrics.getUsedConnectionsAttributes();
    Attributes idleConnectionsAttributes = metrics.getIdleConnectionsAttributes();

    BatchCallback callback =
        metrics.batchCallback(
            () -> {
              connections.record(dataSource.getNumActive(), usedConnectionsAttributes);
              connections.record(dataSource.getNumIdle(), idleConnectionsAttributes);
              minIdleConnections.record(dataSource.getMinIdle(), attributes);
              maxIdleConnections.record(dataSource.getMaxIdle(), attributes);
              maxConnections.record(dataSource.getMaxTotal(), attributes);
            },
            connections,
            minIdleConnections,
            maxIdleConnections,
            maxConnections);

    dataSourceMetrics.put(dataSource, callback);
  }

  public static void unregisterMetrics(BasicDataSourceMXBean dataSource) {
    BatchCallback callback = dataSourceMetrics.remove(dataSource);
    if (callback != null) {
      callback.close();
    }
  }

  private DataSourceMetrics() {}
}
