/*
    * 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.omid.timestamp.storage;
  
  import org.apache.curator.framework.CuratorFramework;
  import org.apache.curator.framework.recipes.atomic.AtomicValue;
  import org.apache.curator.framework.recipes.atomic.DistributedAtomicLong;
  import org.apache.curator.retry.RetryNTimes;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.inject.Inject;
  import java.io.IOException;
  
  import static org.apache.omid.timestamp.storage.ZKTimestampPaths.TIMESTAMP_ZNODE;
  
  class ZKTimestampStorage implements TimestampStorage {
  
      private static final Logger LOG = LoggerFactory.getLogger(ZKTimestampStorage.class);
  
      static final long INITIAL_MAX_TS_VALUE = 0;
  
      private final DistributedAtomicLong timestamp;
  
      @Inject
      public ZKTimestampStorage(CuratorFramework zkClient) throws Exception {
          LOG.info("ZK Client state {}", zkClient.getState());
          timestamp = new DistributedAtomicLong(zkClient, TIMESTAMP_ZNODE, new RetryNTimes(3, 1000)); // TODO Configure
          // this?
          if (timestamp.initialize(INITIAL_MAX_TS_VALUE)) {
              LOG.info("Timestamp value in ZNode initialized to {}", INITIAL_MAX_TS_VALUE);
          }
      }
  
      @Override
      public void updateMaxTimestamp(long previousMaxTimestamp, long newMaxTimestamp) throws IOException {
  
          if (newMaxTimestamp < 0) {
              LOG.error("Negative value received for maxTimestamp: {}", newMaxTimestamp);
              throw new IllegalArgumentException();
          }
          if (newMaxTimestamp <= previousMaxTimestamp) {
              LOG.error("maxTimestamp {} <= previousMaxTimesamp: {}", newMaxTimestamp, previousMaxTimestamp);
              throw new IllegalArgumentException();
          }
          AtomicValue<Long> compareAndSet;
          try {
              compareAndSet = timestamp.compareAndSet(previousMaxTimestamp, newMaxTimestamp);
          } catch (Exception e) {
              throw new IOException("Problem setting timestamp in ZK", e);
          }
          if (!compareAndSet.succeeded()) { // We have to explicitly check for success (See Curator doc)
              throw new IOException("GetAndSet operation for storing timestamp in ZK did not succeed "
                      + compareAndSet.preValue() + " " + compareAndSet.postValue());
          }
  
      }
  
      @Override
      public long getMaxTimestamp() throws IOException {
  
          AtomicValue<Long> atomicValue;
          try {
              atomicValue = timestamp.get();
          } catch (Exception e) {
              throw new IOException("Problem getting data from ZK", e);
          }
          if (!atomicValue.succeeded()) { // We have to explicitly check for success (See Curator doc)
              throw new IOException("Get operation to obtain timestamp from ZK did not succeed");
          }
          return atomicValue.postValue();
  
      }
  
  }