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.alerts;
  
  import javax.annotation.Nullable;
  
  import org.apache.ambari.server.state.AlertState;
  
  /**
   * I'm a 3 level threshold where each level corresponds to ok, warn and critical levels.
   * The levels are either increasing or decreasing numerical sequences.
   * My main responsibility is to map incoming values to {@link AlertState} based on the threshold levels.
   */
  public class Threshold {
    private final Double okValue;
    private final double warnValue;
    private final double critValue;
  
    public Threshold(@Nullable Double okValue, double warnValue, double critValue) {
      this.okValue = okValue;
      this.warnValue = warnValue;
      this.critValue = critValue;
    }
  
    public AlertState state(double value) {
      return directionUp() ? stateWhenDirectionUp(value) : stateWhenDirectionDown(value);
    }
  
    private boolean directionUp() {
      return critValue >= warnValue;
    }
  
    private AlertState stateWhenDirectionUp(double value) {
      if (value >= critValue) {
        return AlertState.CRITICAL;
      }
      if (value >= warnValue) {
        return AlertState.WARNING;
      }
      if (okValue == null || value >= okValue) {
        return AlertState.OK;
      }
      return AlertState.UNKNOWN;
    }
  
    private AlertState stateWhenDirectionDown(double value) {
      if (value <= critValue) {
        return AlertState.CRITICAL;
      }
      if (value <= warnValue) {
        return AlertState.WARNING;
      }
      if (okValue == null || value <= okValue) {
        return AlertState.OK;
      }
      return AlertState.UNKNOWN;
    }
  }
  