/*
 * 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.fluo.integration.impl;

import java.util.Collections;
import java.util.List;
import java.util.NoSuchElementException;

import org.apache.curator.framework.CuratorFramework;
import org.apache.fluo.accumulo.util.LongUtil;
import org.apache.fluo.accumulo.util.ZookeeperPath;
import org.apache.fluo.core.impl.TimestampTracker;
import org.apache.fluo.core.impl.TransactorID;
import org.apache.fluo.integration.ITBaseImpl;
import org.apache.zookeeper.KeeperException.NoNodeException;
import org.junit.Assert;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.Timeout;

/**
 * Tests TimestampTracker class
 */
public class TimestampTrackerIT extends ITBaseImpl {
  @Rule
  public Timeout globalTimeout = Timeout.seconds(getTestTimeout());

  @Test(expected = NoSuchElementException.class)
  public void testTsNoElement() {
    TimestampTracker tracker = env.getSharedResources().getTimestampTracker();
    Assert.assertTrue(tracker.isEmpty());
    tracker.getOldestActiveTimestamp();
  }

  @Test
  public void testTrackingWithNoUpdate() throws Exception {
    TimestampTracker tracker = new TimestampTracker(env, new TransactorID(env));
    Assert.assertTrue(tracker.isEmpty());
    Assert.assertFalse(zkNodeExists(tracker));
    final long ts1 = tracker.allocateTimestamp().getTxTimestamp();
    Assert.assertFalse(tracker.isEmpty());
    Assert.assertTrue(zkNodeExists(tracker));
    Assert.assertTrue(ts1 > zkNodeValue(tracker));
    Assert.assertEquals(tracker.getZookeeperTimestamp(), zkNodeValue(tracker));
    Assert.assertEquals(ts1, tracker.getOldestActiveTimestamp());
    final long ts2 = tracker.allocateTimestamp().getTxTimestamp();
    Assert.assertEquals(ts1, tracker.getOldestActiveTimestamp());
    tracker.removeTimestamp(ts1);
    Assert.assertFalse(tracker.isEmpty());
    Assert.assertEquals(ts2, tracker.getOldestActiveTimestamp());
    Assert.assertFalse(tracker.isEmpty());
    Assert.assertTrue(ts1 > zkNodeValue(tracker));
    Assert.assertEquals(tracker.getZookeeperTimestamp(), zkNodeValue(tracker));
    tracker.removeTimestamp(ts2);
    Assert.assertTrue(tracker.isEmpty());
    Assert.assertTrue(zkNodeExists(tracker));
    tracker.close();
  }

  @Test
  public void testTrackingWithZkUpdate() throws Exception {
    TimestampTracker tracker = new TimestampTracker(env, new TransactorID(env), 5);
    final long ts1 = tracker.allocateTimestamp().getTxTimestamp();
    Thread.sleep(15);
    Assert.assertNotNull(ts1);
    Assert.assertTrue(zkNodeExists(tracker));
    Assert.assertNotNull(zkNodeValue(tracker));
    Assert.assertEquals(tracker.getZookeeperTimestamp(), zkNodeValue(tracker));
    Assert.assertEquals(ts1, tracker.getOldestActiveTimestamp());
    final long ts2 = tracker.allocateTimestamp().getTxTimestamp();
    Assert.assertEquals(ts1, tracker.getOldestActiveTimestamp());
    Thread.sleep(15);
    tracker.removeTimestamp(ts1);
    Thread.sleep(15);
    Assert.assertEquals(ts2, tracker.getOldestActiveTimestamp());
    Assert.assertEquals(ts2, zkNodeValue(tracker));
    tracker.removeTimestamp(ts2);
    Thread.sleep(15);
    Assert.assertTrue(tracker.isEmpty());
    Assert.assertFalse(zkNodeExists(tracker));
    tracker.close();
  }

  @Test
  public void testTimestampUtilGetOldestTs() throws Exception {
    Assert.assertEquals(0, getOldestTs());
    TimestampTracker tr1 = new TimestampTracker(env, new TransactorID(env), 5);
    final long ts1 = tr1.allocateTimestamp().getTxTimestamp();
    Thread.sleep(15);
    Assert.assertEquals(tr1.getZookeeperTimestamp(), getOldestTs());
    TimestampTracker tr2 = new TimestampTracker(env, new TransactorID(env), 5);
    final long ts2 = tr2.allocateTimestamp().getTxTimestamp();
    TimestampTracker tr3 = new TimestampTracker(env, new TransactorID(env), 5);
    final long ts3 = tr3.allocateTimestamp().getTxTimestamp();
    Thread.sleep(15);
    Assert.assertEquals(ts1, getOldestTs());
    tr1.removeTimestamp(ts1);
    Thread.sleep(15);
    Assert.assertEquals(ts2, getOldestTs());
    tr2.removeTimestamp(ts2);
    Thread.sleep(15);
    Assert.assertEquals(ts3, getOldestTs());
    tr3.removeTimestamp(ts3);
    tr1.close();
    tr2.close();
    tr3.close();
  }

  private long getOldestTs() throws Exception {

    CuratorFramework curator = env.getSharedResources().getCurator();
    List<String> children;
    try {
      children = curator.getChildren().forPath(ZookeeperPath.TRANSACTOR_TIMESTAMPS);
    } catch (NoNodeException nne) {
      children = Collections.emptyList();
    }

    long oldestTs = Long.MAX_VALUE;

    for (String child : children) {
      Long ts = LongUtil.fromByteArray(
          curator.getData().forPath(ZookeeperPath.TRANSACTOR_TIMESTAMPS + "/" + child));
      if (ts < oldestTs) {
        oldestTs = ts;
      }
    }

    return oldestTs == Long.MAX_VALUE ? 0 : oldestTs;
  }

  private boolean zkNodeExists(TimestampTracker tracker) throws Exception {
    return env.getSharedResources().getCurator().checkExists()
        .forPath(tracker.getNodePath()) != null;
  }

  private long zkNodeValue(TimestampTracker tracker) throws Exception {
    if (zkNodeExists(tracker) == false) {
      throw new IllegalStateException("node does not exist");
    }
    return LongUtil.fromByteArray(
        env.getSharedResources().getCurator().getData().forPath(tracker.getNodePath()));
  }
}