/*
 * Copyright 2017 LinkedIn Corp. Licensed under the BSD 2-Clause License (the "License"). See License in the project root for license information.
 */

package com.linkedin.kafka.cruisecontrol.model;

import com.linkedin.cruisecontrol.monitor.sampling.aggregator.AggregatedMetricValues;
import com.linkedin.kafka.cruisecontrol.common.Resource;
import com.linkedin.kafka.cruisecontrol.config.BrokerCapacityInfo;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Serializable;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.kafka.common.TopicPartition;

import static com.linkedin.kafka.cruisecontrol.common.Resource.DISK;

public class Host implements Serializable {
  private static final double DEAD_HOST_CAPACITY = -1.0;
  private final Map<Integer, Broker> _brokers;
  private final Set<Replica> _replicas;
  private final Rack _rack;
  private final String _name;
  private final Load _load;
  private final double[] _hostCapacity;
  private int _aliveBrokers;

  Host(String name, Rack rack) {
    _name = name;
    _brokers = new HashMap<>();
    _replicas = new HashSet<>();
    _rack = rack;
    _load = new Load();
    _hostCapacity = new double[Resource.cachedValues().size()];
    _aliveBrokers = 0;
  }

  // Getters
  public Rack rack() {
    return _rack;
  }

  public Broker broker(int brokerId) {
    return _brokers.get(brokerId);
  }

  public Collection<Broker> brokers() {
    return _brokers.values();
  }

  public Set<Replica> replicas() {
    return _replicas;
  }

  /**
   * Get the number of replicas with the given topic name in this host.
   *
   * @param topic Name of the topic for which the number of replicas in this rack will be counted.
   * @return Number of replicas with the given topic name in this host.
   */
  public int numTopicReplicas(String topic) {
    int numTopicReplicas = 0;

    for (Broker broker : _brokers.values()) {
      numTopicReplicas += broker.numReplicasOfTopicInBroker(topic);
    }
    return numTopicReplicas;
  }

  /**
   * @return All the topics that have at least one partition on the host.
   */
  public Set<String> topics() {
    Set<String> topics = new HashSet<>();
    _brokers.values().forEach(broker -> topics.addAll(broker.topics()));
    return topics;
  }

  /**
   * Get host capacity for the requested resource. Rack capacity represents the total capacity of the live
   * brokers in the rack for the requested resource.
   *
   * @param resource Resource for which capacity will be provided.
   * @return Alive host capacity of the resource.
   */
  public double capacityFor(Resource resource) {
    return _aliveBrokers > 0 ? _hostCapacity[resource.id()] : DEAD_HOST_CAPACITY;
  }

  /**
   * @return whether the host is alive. The host is alive as long as it has at least one broker alive.
   */
  public boolean isAlive() {
    for (Broker broker : _brokers.values()) {
      if (broker.isAlive()) {
        return true;
      }
    }
    return false;
  }

  /**
   * @return The load on the rack.
   */
  public Load load() {
    return _load;
  }

  /**
   * Mark specified disk dead and update the capacity
   *
   * @param brokerId The id of broker which host the disk.
   * @param logdir Log directory of the disk.
   * @return The disk capacity lost.
   */
  double markDiskDead(int brokerId, String logdir) {
    Broker broker = broker(brokerId);
    double capacityLost = broker.markDiskDead(logdir);
    _hostCapacity[DISK.id()] -= capacityLost;
    return capacityLost;
  }

  /**
   * @return The name of the host
   */
  public String name() {
    return _name;
  }

  /**
   * Create a broker under this host, and get the created broker.
   *
   * @param brokerId Id of the broker to be created.
   * @param brokerCapacityInfo Capacity information of the created broker.
   * @param populateReplicaPlacementInfo Whether populate replica placement over disk information or not.
   * @return Created broker.
   */
  Broker createBroker(Integer brokerId, BrokerCapacityInfo brokerCapacityInfo, boolean populateReplicaPlacementInfo) {
    Broker broker = new Broker(this, brokerId, brokerCapacityInfo, populateReplicaPlacementInfo);
    _brokers.put(brokerId, broker);
    _aliveBrokers++;
    for (Map.Entry<Resource, Double> entry : brokerCapacityInfo.capacity().entrySet()) {
      Resource resource = entry.getKey();
      _hostCapacity[resource.id()] += (resource == Resource.CPU) ? (entry.getValue() * brokerCapacityInfo.numCpuCores())
                                                                 : entry.getValue();
    }
    return broker;
  }

  /**
   * Set broker state and update the capacity
   */
  void setBrokerState(int brokerId, Broker.State newState) {
    Broker broker = broker(brokerId);
    if (broker.isAlive() && newState == Broker.State.DEAD) {
      for (Resource r : Resource.cachedValues()) {
        _hostCapacity[r.id()] -= broker.capacityFor(r);
      }
      _aliveBrokers--;
    } else if (!broker.isAlive() && newState != Broker.State.DEAD) {
      for (Resource r : Resource.cachedValues()) {
        _hostCapacity[r.id()] += broker.capacityFor(r);
      }
      _aliveBrokers++;
    }
    broker.setState(newState);
  }

  void addReplica(Replica replica) {
    _replicas.add(replica);
    _brokers.get(replica.broker().id()).addReplica(replica);
    _load.addLoad(replica.load());
  }

  Replica removeReplica(int brokerId, TopicPartition tp) {
    Broker broker = _brokers.get(brokerId);
    if (broker == null) {
      throw new IllegalStateException(String.format("Cannot remove replica for %s from broker %s because "
                                                        + "it does not exist in host %s", tp, brokerId, _name));
    }
    Replica replica = broker.removeReplica(tp);
    _replicas.remove(replica);
    _load.subtractLoad(replica.load());
    return replica;
  }

  AggregatedMetricValues makeFollower(int brokerId, TopicPartition tp) {
    Broker broker = broker(brokerId);
    if (broker == null) {
      throw new IllegalStateException(String.format("Cannot make replica %s on broker %d as follower because the broker"
                                                        + " does not exist in host %s", tp, brokerId, _name));
    }
    AggregatedMetricValues leadershipLoadDelta = broker.makeFollower(tp);

    // Remove leadership load from recent load.
    _load.subtractLoad(leadershipLoadDelta);
    return leadershipLoadDelta;
  }

  void makeLeader(int brokerId,
                  TopicPartition tp,
                  AggregatedMetricValues leadershipLoadDelta) {
    Broker broker = _brokers.get(brokerId);
    broker.makeLeader(tp, leadershipLoadDelta);
    // Add leadership load to recent load.
    _load.addLoad(leadershipLoadDelta);
  }

  void setReplicaLoad(int brokerId,
                      TopicPartition tp,
                      AggregatedMetricValues aggregatedMetricValues,
                      List<Long> windows) {
    Broker broker = _brokers.get(brokerId);
    broker.setReplicaLoad(tp, aggregatedMetricValues, windows);
    _load.addMetricValues(aggregatedMetricValues, windows);
  }

  void clearLoad() {
    _brokers.values().forEach(Broker::clearLoad);
    _load.clearLoad();
  }

  /**
   * @return An object that can be further used to encode into JSON.
   */
  public Map<String, Object> getJsonStructure() {
    Map<String, Object> hostMap = new HashMap<>();
    List<Map<String, Object>> brokerList = new ArrayList<>();
    for (Broker broker : _brokers.values()) {
      brokerList.add(broker.getJsonStructure());
    }
    hostMap.put(ModelUtils.NAME, _name);
    hostMap.put(ModelUtils.BROKERS, brokerList);
    return hostMap;
  }

  /**
   * Write to the given output stream.
   *
   * @param out Output stream.
   */
  public void writeTo(OutputStream out) throws IOException {
    String host = String.format("<Host name=\"%s\">%n", _name);
    out.write(host.getBytes(StandardCharsets.UTF_8));
    for (Broker broker : _brokers.values()) {
      broker.writeTo(out);
    }
    out.write("</Host>%n".getBytes(StandardCharsets.UTF_8));
  }

  @Override
  public String toString() {
    StringBuilder host = new StringBuilder().append(String.format("<Host name=\"%s\">%n", _name));

    for (Broker broker : _brokers.values()) {
      host.append(broker.toString());
    }

    return host.append("</Host>%n").toString();
  }

}
