package org.apache.helix.integration;

/*
 * 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.
 */

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;
import org.apache.helix.HelixDataAccessor;
import org.apache.helix.HelixException;
import org.apache.helix.SystemPropertyKeys;
import org.apache.helix.TestHelper;
import org.apache.helix.integration.manager.ClusterControllerManager;
import org.apache.helix.integration.manager.MockParticipantManager;
import org.apache.helix.integration.task.MockTask;
import org.apache.helix.integration.task.TaskTestBase;
import org.apache.helix.integration.task.TaskTestUtil;
import org.apache.helix.integration.task.WorkflowGenerator;
import org.apache.helix.manager.zk.ZKHelixDataAccessor;
import org.apache.helix.manager.zk.ZNRecordSerializer;
import org.apache.helix.manager.zk.ZkBaseDataAccessor;
import org.apache.helix.task.JobConfig;
import org.apache.helix.task.JobQueue;
import org.apache.helix.task.TaskState;
import org.apache.helix.task.WorkflowContext;
import org.apache.helix.tools.ClusterSetup;
import org.apache.helix.tools.ClusterVerifiers.BestPossibleExternalViewVerifier;
import org.apache.helix.tools.ClusterVerifiers.ZkHelixClusterVerifier;
import org.apache.helix.zookeeper.api.client.HelixZkClient;
import org.apache.helix.zookeeper.impl.factory.SharedZkClientFactory;
import org.apache.helix.zookeeper.zkclient.ZkServer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.testng.Assert;
import org.testng.annotations.AfterClass;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;

public class TestZkConnectionLost extends TaskTestBase {
  private static final Logger LOG = LoggerFactory.getLogger(TestZkConnectionLost.class);

  private final AtomicReference<ZkServer> _zkServerRef = new AtomicReference<>();

  private String _zkAddr = "localhost:21893";
  private ClusterSetup _setupTool;
  private HelixZkClient _zkClient;

  @BeforeClass
  public void beforeClass() throws Exception {
    ZkServer zkServer = TestHelper.startZkServer(_zkAddr);
    _zkServerRef.set(zkServer);
    _zkClient = SharedZkClientFactory.getInstance()
        .buildZkClient(new HelixZkClient.ZkConnectionConfig(_zkAddr));
    _zkClient.setZkSerializer(new ZNRecordSerializer());
    _setupTool = new ClusterSetup(_zkClient);
    _participants = new MockParticipantManager[_numNodes];
    _setupTool.addCluster(CLUSTER_NAME, true);
    setupParticipants(_setupTool);
    setupDBs(_setupTool);
    createManagers(_zkAddr, CLUSTER_NAME);

    // start controller
    String controllerName = CONTROLLER_PREFIX + "_0";
    _controller = new ClusterControllerManager(_zkAddr, CLUSTER_NAME, controllerName);
    _controller.syncStart();

    ZkHelixClusterVerifier clusterVerifier =
        new BestPossibleExternalViewVerifier.Builder(CLUSTER_NAME).setZkAddr(_zkAddr)
            .setWaitTillVerify(TestHelper.DEFAULT_REBALANCE_PROCESSING_WAIT_TIME)
            .build();
    try {
      Assert.assertTrue(clusterVerifier.verifyByPolling());
    } finally {
      clusterVerifier.close();
    }
  }

  @AfterClass
  public void afterClass() throws Exception {
    if (_controller != null && _controller.isConnected()) {
      _controller.syncStop();
    }
    if (_manager != null && _manager.isConnected()) {
      _manager.disconnect();
    }
    stopParticipants();
    TestHelper.dropCluster(CLUSTER_NAME, _zkClient, _setupTool);
    _zkClient.close();
    TestHelper.stopZkServer(_zkServerRef.get());
  }

  @Test
  public void testDisconnectWhenConnectionBreak() throws Exception {
    String controllerName = CONTROLLER_PREFIX + "_" + TestHelper.getTestMethodName();
    ClusterControllerManager controllerManager =
        new ClusterControllerManager(_zkAddr, CLUSTER_NAME, controllerName);
    controllerManager.syncStart();

    TestHelper.stopZkServer(_zkServerRef.get());
    AtomicBoolean disconnected = new AtomicBoolean(false);
    Thread testThread = new Thread("Testing HelixManager disconnect") {
      @Override
      public void run() {
        try {
          controllerManager.disconnect();
        } finally {
          disconnected.set(true);
        }
      }
    };
    try {
      testThread.start();
      // Add timeout to prevent test from hanging forever if disconnect() hangs
      testThread.join(10000);
      Assert.assertTrue(disconnected.get(),
          "disconnect() should complete within 10 seconds");
      Assert.assertFalse(controllerManager.isConnected());
    } finally {
      if (testThread.isAlive()) {
        testThread.stop();
        TestHelper.verify(() -> testThread.getState().equals(Thread.State.TERMINATED),
            TestHelper.WAIT_DURATION);
      }
      _zkServerRef.set(TestHelper.startZkServer(_zkAddr, null, false));
    }
  }

  @Test (enabled = false)
  public void testLostZkConnection() throws Exception {
    System.setProperty(SystemPropertyKeys.ZK_WAIT_CONNECTED_TIMEOUT, "5000");
    System.setProperty(SystemPropertyKeys.ZK_SESSION_TIMEOUT, "5000");
    try {
      String queueName = TestHelper.getTestMethodName();
      startParticipants(_zkAddr);
      HelixDataAccessor accessor =
          new ZKHelixDataAccessor(CLUSTER_NAME, new ZkBaseDataAccessor(_zkAddr));
      Assert.assertTrue(TestHelper.verify(() -> {
        List<String> liveInstances = accessor.getChildNames(accessor.keyBuilder().liveInstances());
        for (MockParticipantManager participant : _participants) {
          if (!liveInstances.contains(participant.getInstanceName())
              || !participant.isConnected()) {
            return false;
          }
        }
        return true;
      }, TestHelper.WAIT_DURATION));

      // Create a queue
      LOG.info("Starting job-queue: " + queueName);
      JobQueue.Builder queueBuild = TaskTestUtil.buildRecurrentJobQueue(queueName, 0, 60);
      createAndEnqueueJob(queueBuild, 3);
      _driver.start(queueBuild.build());
      restartZkServer();
      try {
        WorkflowContext wCtx = TaskTestUtil.pollForWorkflowContext(_driver, queueName);
        String scheduledQueue = wCtx.getLastScheduledSingleWorkflow();
        _driver.pollForWorkflowState(scheduledQueue, 30000, TaskState.COMPLETED);
      } catch (Exception e) {
        // 2nd try because ZK connection problem might prevent the first recurrent workflow to get
        // scheduled
        WorkflowContext wCtx = TaskTestUtil.pollForWorkflowContext(_driver, queueName);
        String scheduledQueue = wCtx.getLastScheduledSingleWorkflow();
        _driver.pollForWorkflowState(scheduledQueue, 30000, TaskState.COMPLETED);
      }
    } finally {
      System.clearProperty(SystemPropertyKeys.ZK_WAIT_CONNECTED_TIMEOUT);
      System.clearProperty(SystemPropertyKeys.ZK_SESSION_TIMEOUT);
    }
  }

  @Test(dependsOnMethods = {
      "testLostZkConnection"
  }, enabled = false)
  public void testLostZkConnectionNegative() throws Exception {
    System.setProperty(SystemPropertyKeys.ZK_WAIT_CONNECTED_TIMEOUT, "10");
    System.setProperty(SystemPropertyKeys.ZK_SESSION_TIMEOUT, "1000");

    try {
      String queueName = TestHelper.getTestMethodName();

      stopParticipants();
      startParticipants(_zkAddr);

      LOG.info("Starting job-queue: " + queueName);
      JobQueue.Builder queueBuild = TaskTestUtil.buildRecurrentJobQueue(queueName, 0, 6000);
      createAndEnqueueJob(queueBuild, 3);

      _driver.start(queueBuild.build());

      restartZkServer();

      WorkflowContext wCtx = TaskTestUtil.pollForWorkflowContext(_driver, queueName);
      // ensure job 1 is started before stop it
      String scheduledQueue = wCtx.getLastScheduledSingleWorkflow();

      try {
        _driver.pollForWorkflowState(scheduledQueue, 30000, TaskState.COMPLETED);
        Assert.fail("Test failure!");
      } catch (HelixException ex) {
        // test succeeded
      }
    } finally {
      System.clearProperty(SystemPropertyKeys.ZK_WAIT_CONNECTED_TIMEOUT);
      System.clearProperty(SystemPropertyKeys.ZK_SESSION_TIMEOUT);
    }
  }

  private void restartZkServer() throws ExecutionException, InterruptedException {
    // shutdown and restart zk for a couple of times
    for (int i = 0; i < 4; i++) {
      Executors.newSingleThreadExecutor().submit(() -> {
        try {
          Thread.sleep(300);
          System.out.println(System.currentTimeMillis() + ": Shutdown ZK server.");
          TestHelper.stopZkServer(_zkServerRef.get());
          Thread.sleep(300);
          System.out.println("Restart ZK server");
          _zkServerRef.set(TestHelper.startZkServer(_zkAddr, null, false));
        } catch (Exception e) {
          LOG.error(e.getMessage(), e);
        }
      }).get();
    }
  }

  private List<String> createAndEnqueueJob(JobQueue.Builder queueBuild, int jobCount) {
    List<String> currentJobNames = new ArrayList<>();
    for (int i = 0; i < jobCount; i++) {
      String targetPartition = (i == 0) ? "MASTER" : "SLAVE";

      JobConfig.Builder jobConfig = new JobConfig.Builder().setCommand(MockTask.TASK_COMMAND)
          .setTargetResource(WorkflowGenerator.DEFAULT_TGT_DB)
          .setTargetPartitionStates(Sets.newHashSet(targetPartition))
          .setJobCommandConfigMap(ImmutableMap.of(MockTask.JOB_DELAY, "100"));
      String jobName = targetPartition.toLowerCase() + "Job" + i;
      queueBuild.enqueueJob(jobName, jobConfig);
      currentJobNames.add(jobName);
    }
    Assert.assertEquals(currentJobNames.size(), jobCount);
    return currentJobNames;
  }
}
