/*
    * 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.commons.monitoring.gauges;
  
  import org.apache.commons.monitoring.Role;
  import org.apache.commons.monitoring.store.DataStore;
  
  import java.util.Map;
  import java.util.Timer;
  import java.util.TimerTask;
  import java.util.concurrent.ConcurrentHashMap;
  
  public final class DefaultGaugeManager implements GaugeManager {
      private final Map<Role, Timer> timers = new ConcurrentHashMap<Role, Timer>();
      private final DataStore store;
  
      public DefaultGaugeManager(final DataStore dataStore) {
          store = dataStore;
      }
  
      @Override
      public void stop() {
          for (final Timer timer : timers.values()) {
              timer.cancel();
          }
          timers.clear();
      }
  
      @Override
      public void stopGauge(final Role role) {
          final Timer timer = timers.remove(role);
          if (timer != null) {
              timer.cancel();
          }
      }
  
      @Override
      public void addGauge(final Gauge gauge) {
          final Role role = gauge.role();
  
          this.store.createOrNoopGauge(role);
  
          final Timer timer = new Timer("gauge-" + role.getName() + "-timer", true);
          timers.put(role, timer);
          timer.scheduleAtFixedRate(new GaugeTask(store, gauge), 0, gauge.period());
      }
  
      private static class GaugeTask extends TimerTask {
          private final Gauge gauge;
          private final DataStore store;
  
          public GaugeTask(final DataStore store, final Gauge gauge) {
              this.store = store;
              this.gauge = gauge;
          }
  
          @Override
          public void run() {
              store.addToGauge(gauge, System.currentTimeMillis(), gauge.value());
          }
      }
  }