/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.solr.core;

import java.util.Map;
import java.util.Set;

import com.codahale.metrics.MetricRegistry;
import org.apache.solr.metrics.SolrMetricManager;
import org.apache.solr.metrics.SolrMetricProducer;
import org.apache.solr.metrics.SolrMetricsContext;
import org.apache.solr.util.stats.MetricUtils;

/**
 * Interface for getting various ui friendly strings
 * for use by objects which are 'pluggable' to make server administration
 * easier.
 */
public interface SolrInfoBean {

  /**
   * Category of Solr component.
   */
  enum Category { CONTAINER, ADMIN, CORE, QUERY, UPDATE, CACHE, HIGHLIGHTER, QUERYPARSER, SPELLCHECKER,
    SEARCHER, REPLICATION, TLOG, INDEX, DIRECTORY, HTTP, SECURITY, OTHER }

  /**
   * Top-level group of beans or metrics for a subsystem.
   */
  enum Group { jvm, jetty, node, core, collection, shard, cluster, overseer }

  /**
   * Simple common usage name, e.g. BasicQueryHandler,
   * or fully qualified class name.
   */
  String getName();
  /** Simple one or two line description */
  String getDescription();
  /** Category of this component */
  Category getCategory();

  /** Optionally return a snapshot of metrics that this component reports, or null.
   * Default implementation requires that both {@link #getMetricNames()} and
   * {@link #getMetricRegistry()} return non-null values.
   */
  default Map<String, Object> getMetricsSnapshot() {
    if (getMetricRegistry() == null || getMetricNames() == null) {
      return null;
    }
    return MetricUtils.convertMetrics(getMetricRegistry(), getMetricNames());
  }

  /**
   * Modifiable set of metric names that this component reports (default is null,
   * which means none). If not null then this set is used by {@link #registerMetricName(String)}
   * to capture what metrics names are reported from this component.
   * <p><b>NOTE: this set has to allow iteration under modifications.</b></p>
   */
  default Set<String> getMetricNames() {
    return null;
  }

  /**
   * An instance of {@link MetricRegistry} that this component uses for metrics reporting
   * (default is null, which means no registry).
   */
  default MetricRegistry getMetricRegistry() {
    if (this instanceof SolrMetricProducer) {
      SolrMetricsContext context = ((SolrMetricProducer)this).getSolrMetricsContext();
      return context != null ? context.getMetricRegistry() : null;
    }
    return null;
  }

  /** Register a metric name that this component reports. This method is called by various
   * metric registration methods in {@link org.apache.solr.metrics.SolrMetricManager} in order
   * to capture what metric names are reported from this component (which in turn is called
   * from {@link org.apache.solr.metrics.SolrMetricProducer#initializeMetrics(SolrMetricManager, String, String, String)}).
   * <p>Default implementation registers all metrics added by a component. Implementations may
   * override this to avoid reporting some or all metrics returned by {@link #getMetricsSnapshot()}</p>
   */
  default void registerMetricName(String name) {
    Set<String> names = getMetricNames();
    if (names != null) {
      names.add(name);
    }
  }
}