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/*
 * Copyright 2014-2019 Netflix, Inc.
 *
 * Licensed 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 com.netflix.spectator.jvm;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.management.Attribute;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanInfo;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import javax.management.openmbean.CompositeDataSupport;
import javax.management.openmbean.CompositeType;
import java.lang.management.ManagementFactory;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.TimeUnit;

/**
 * Represents the results from querying data out of JMX.
 */
class JmxData {

  private static final Logger LOGGER = LoggerFactory.getLogger(JmxData.class);

  /** Get data from JMX using object name query expression. */
  static List query(String query) throws Exception {
    return query(new ObjectName(query));
  }

  /** Get data from JMX using object name query expression. */
  static List query(ObjectName query) throws Exception {
    return query(ManagementFactory.getPlatformMBeanServer(), query);
  }

  /** Convert object to string and checking if it fails. */
  @SuppressWarnings("PMD.AvoidCatchingThrowable")
  static String mkString(Object obj) {
    if (obj == null) {
      return "null";
    }
    try {
      return obj.toString() + " (type is " + obj.getClass() + ")";
    } catch (Throwable t) {
      return t.getClass().toString() + ": " + t.getMessage() + " (type is " + obj.getClass() + ")";
    }
  }

  /** Get data from JMX using object name query expression. */
  static List query(MBeanServer server, ObjectName query) throws Exception {
    List data = new ArrayList<>();

    Set names = server.queryNames(query, null);
    LOGGER.trace("query [{}], found {} matches", query, names.size());
    for (ObjectName name : names) {
      MBeanInfo info = server.getMBeanInfo(name);
      MBeanAttributeInfo[] attrs = info.getAttributes();
      String[] attrNames = new String[attrs.length];
      for (int i = 0; i < attrs.length; ++i) {
        attrNames[i] = attrs[i].getName();
      }

      Map stringAttrs = new HashMap<>();
      stringAttrs.put("domain", name.getDomain());
      Map numberAttrs = new HashMap<>();

      for (Attribute attr : server.getAttributes(name, attrNames).asList()) {
        Object obj = attr.getValue();
        if (LOGGER.isTraceEnabled()) {
          LOGGER.trace("attribute [{}][{}] = {}", name, attr.getName(), mkString(obj));
        }

        if (obj instanceof String) {
          stringAttrs.put(attr.getName(), (String) obj);
        } else if (obj instanceof Number) {
          numberAttrs.put(attr.getName(), ((Number) obj).doubleValue());
        } else if (obj instanceof CompositeDataSupport) {
          CompositeDataSupport composite = (CompositeDataSupport) obj;
          CompositeType compositeType = composite.getCompositeType();
          for (String key : compositeType.keySet()) {
            if (composite.containsKey(key)) {
              Object o = composite.get(key);
              String attrKey = attr.getName() + "." + key;
              if (o instanceof Number) {
                numberAttrs.put(attrKey, ((Number) o).doubleValue());
              } else if (o instanceof String) {
                stringAttrs.put(attrKey, (String) o);
              } else if (o instanceof TimeUnit) {
                stringAttrs.put(attrKey, o.toString());
              }
            }
          }
        } else if (obj instanceof TimeUnit) {
          stringAttrs.put(attr.getName(), obj.toString());
        }
      }

      // Add properties from ObjectName after attributes to ensure they have a higher
      // priority if the same key is used both in the Object and as an attribute
      stringAttrs.putAll(name.getKeyPropertyList());

      data.add(new JmxData(name, stringAttrs, numberAttrs));
    }

    return data;
  }

  private final ObjectName name;
  private final Map stringAttrs;
  private final Map numberAttrs;

  /**
   * Create a new instance.
   */
  JmxData(ObjectName name, Map stringAttrs, Map numberAttrs) {
    this.name = name;
    this.stringAttrs = Collections.unmodifiableMap(stringAttrs);
    this.numberAttrs = Collections.unmodifiableMap(numberAttrs);
  }

  /** Return the name of the bean. */
  ObjectName getName() {
    return name;
  }

  /** Return attributes with string values. */
  Map getStringAttrs() {
    return stringAttrs;
  }

  /** Return attributes with numeric values. */
  Map getNumberAttrs() {
    return numberAttrs;
  }

  @Override public String toString() {
    StringBuilder buf = new StringBuilder(256);
    buf.append(name.toString())
        .append("\n- string attributes\n");
    for (Map.Entry entry : new TreeMap<>(stringAttrs).entrySet()) {
      buf.append("  - ").append(entry.getKey()).append(" = ").append(entry.getValue()).append('\n');
    }
    buf.append("- number attributes\n");
    for (Map.Entry entry : new TreeMap<>(numberAttrs).entrySet()) {
      buf.append("  - ").append(entry.getKey()).append(" = ").append(entry.getValue()).append('\n');
    }
    return buf.toString();
  }
}