content: /*
   * 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.ambari.server.state.alert;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.stream.Collectors;
  
  import org.apache.ambari.server.agent.StaleAlert;
  import org.apache.ambari.server.alerts.StaleAlertRunnable;
  import org.apache.commons.lang.StringUtils;
  import org.apache.commons.lang.math.NumberUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.google.inject.Singleton;
  
  @Singleton
  public class AlertHelper {
    /**
     * Logger.
     */
    private final static Logger LOG = LoggerFactory.getLogger(AlertHelper.class);
  
    /**
     * The multiplier for the interval of the definition which is being checked
     * for staleness. If this value is {@code 2}, then alerts are considered stale
     * if they haven't run in more than 2x their interval value.
     */
    private static final int INTERVAL_WAIT_FACTOR_DEFAULT = 2;
  
    /**
     * A parameter which exposes the interval multipler to use for calculating
     * staleness. If this does not exist, then
     * {@link #INTERVAL_WAIT_FACTOR_DEFAULT} will be used.
     */
    private static final String STALE_INTERVAL_MULTIPLIER_PARAM_KEY = "stale.interval.multiplier";
  
    /**
     * Contains stale alerts with stale timestamp by host id.
     */
    private ConcurrentMap<Long, ConcurrentMap<Long, Long>> staleAlerts = new ConcurrentHashMap<>();
  
    /**
     * Gets the wait factor multiplier off of the definition, returning
     * {@link #INTERVAL_WAIT_FACTOR_DEFAULT} if not specified. This will look for
     * {@link #STALE_INTERVAL_MULTIPLIER_PARAM_KEY} in the definition parameters.
     * The value returned from this method will be guaranteed to be in the range
     * of 2 to 10.
     *
     * @param definition
     *          the definition to read
     * @return the wait factor interval multiplier
     */
    public int getWaitFactorMultiplier(AlertDefinition definition) {
      // start with the default
      int waitFactor = INTERVAL_WAIT_FACTOR_DEFAULT;
  
      // coerce the entity into a business object so that the list of parameters
      // can be extracted and used for threshold calculation
      try {
        ServerSource serverSource = (ServerSource) definition.getSource();
        List<ParameterizedSource.AlertParameter> parameters = serverSource.getParameters();
        for (ParameterizedSource.AlertParameter parameter : parameters) {
          Object value = parameter.getValue();
  
          if (StringUtils.equals(parameter.getName(), STALE_INTERVAL_MULTIPLIER_PARAM_KEY)) {
            waitFactor = getThresholdValue(value, INTERVAL_WAIT_FACTOR_DEFAULT);
          }
        }
  
        if (waitFactor < 2 || waitFactor > 10) {
          LOG.warn(
              "The interval multipler of {} is outside the valid range for {} and will be set to 2",
              waitFactor, definition.getLabel());
  
          waitFactor = 2;
        }
      } catch (Exception exception) {
        LOG.error("Unable to read the {} parameter for {}", STALE_INTERVAL_MULTIPLIER_PARAM_KEY,
            StaleAlertRunnable.class.getSimpleName(), exception);
      }
  
      return waitFactor;
    }
  
    /**
     * Converts the given value to an integer safely.
     *
     * @param value
     * @param defaultValue
     * @return
     */
    public int getThresholdValue(Object value, int defaultValue) {
      if (null == value) {
        return defaultValue;
      }
  
      if (value instanceof Number) {
        return ((Number) value).intValue();
      }
  
      if (!(value instanceof String)) {
        value = value.toString();
      }
  
      if (!NumberUtils.isNumber((String) value)) {
        return defaultValue;
      }
  
      Number number = NumberUtils.createNumber((String) value);
      return number.intValue();
    }
  
    /**
     * Saves stale alerts for specified host.
     * @param hostId host id
     * @param staleAlertsDefinitionId list of stale alerts
     */
    public void addStaleAlerts(Long hostId, List<StaleAlert> staleAlertsDefinitionId) {
      staleAlerts.put(hostId, new ConcurrentHashMap<>());
      ConcurrentMap<Long, Long> hostStaleAlerts = staleAlerts.get(hostId);
      staleAlertsDefinitionId.forEach(s -> hostStaleAlerts.put(s.getId(), s.getTimestamp()));
    }
  
    /**
     * Retrieves stale alerts for specified host.
     * @param hostId host id
     * @return
     */
    public Map<Long, Long> getStaleAlerts(Long hostId) {
      return staleAlerts.containsKey(hostId) ? new HashMap<>(staleAlerts.get(hostId)) : Collections.emptyMap();
    }
  
    /**
     * Removes all stale alerts for specified host.
     * @param hostId host id
     */
    public void clearStaleAlerts(Long hostId) {
      staleAlerts.remove(hostId);
    }
  
    /**
     * Removes specified stale alert from specified host.
     * @param hostId host id.
     * @param definitionId alert definition id.
     */
    public void clearStaleAlert(Long hostId, Long definitionId) {
      if (staleAlerts.containsKey(hostId)) {
        staleAlerts.get(hostId).remove(definitionId);
      }
    }
  
    /**
     * Removes specified stale alert from specified host.
     * @param definitionId alert definition id.
     */
    public void clearStaleAlert(Long definitionId) {
      staleAlerts.forEach((k, v) -> v.remove(definitionId));
    }
  
    /**
     * Retrieves all host ids containing specified definition id.
     * @param definitionId alert definition id.
     * @return host ids list.
     */
    public List<Long> getHostIdsByDefinitionId(Long definitionId) {
      return staleAlerts.entrySet().stream()
          .filter(e -> e.getValue().containsKey(definitionId))
          .map(e -> e.getKey()).collect(Collectors.toList());
    }
  }
  