/*
    * 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.hadoop.hbase.regionserver.compactions;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  
  @InterfaceAudience.Private
  public abstract class OffPeakHours {
    private static final Log LOG = LogFactory.getLog(OffPeakHours.class);
  
    public static final OffPeakHours DISABLED = new OffPeakHours() {
      @Override public boolean isOffPeakHour() { return false; }
      @Override public boolean isOffPeakHour(int targetHour) { return false; }
    };
  
    public static OffPeakHours getInstance(Configuration conf) {
      int startHour = conf.getInt(CompactionConfiguration.HBASE_HSTORE_OFFPEAK_START_HOUR, -1);
      int endHour = conf.getInt(CompactionConfiguration.HBASE_HSTORE_OFFPEAK_END_HOUR, -1);
      return getInstance(startHour, endHour);
    }
  
    /**
     * @param startHour inclusive
     * @param endHour exclusive
     */
    public static OffPeakHours getInstance(int startHour, int endHour) {
      if (startHour == -1 && endHour == -1) {
        return DISABLED;
      }
  
      if (! isValidHour(startHour) || ! isValidHour(endHour)) {
        if (LOG.isWarnEnabled()) {
          LOG.warn("Ignoring invalid start/end hour for peak hour : start = " +
              startHour + " end = " + endHour +
              ". Valid numbers are [0-23]");
        }
        return DISABLED;
      }
  
      if (startHour == endHour) {
        return DISABLED;
      }
  
      return new OffPeakHoursImpl(startHour, endHour);
    }
  
    private static boolean isValidHour(int hour) {
      return 0 <= hour && hour <= 23;
    }
  
    /**
     * @return whether {@code targetHour} is off-peak hour
     */
    public abstract boolean isOffPeakHour(int targetHour);
  
    /**
     * @return whether it is off-peak hour
     */
    public abstract boolean isOffPeakHour();
  
    private static class OffPeakHoursImpl extends OffPeakHours {
      final int startHour;
      final int endHour;
  
      /**
       * @param startHour inclusive
       * @param endHour exclusive
       */
      OffPeakHoursImpl(int startHour, int endHour) {
        this.startHour = startHour;
        this.endHour = endHour;
      }
  
      @Override
      public boolean isOffPeakHour() {
        return isOffPeakHour(CurrentHourProvider.getCurrentHour());
      }
  
      @Override
      public boolean isOffPeakHour(int targetHour) {
        if (startHour <= endHour) {
         return startHour <= targetHour && targetHour < endHour;
       }
       return targetHour < endHour || startHour <= targetHour;
     }
   }
 }