package org.apache.helix.controller.rebalancer;

/*
 * 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.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Set;
import java.util.UUID;
import org.apache.helix.ZNRecord;
import org.apache.helix.controller.stages.BaseStageTest;
import org.apache.helix.controller.stages.CurrentStateOutput;
import org.apache.helix.model.BuiltInStateModelDefinitions;
import org.apache.helix.model.ClusterConfig;
import org.apache.helix.model.IdealState;
import org.apache.helix.model.Message;
import org.apache.helix.model.Partition;
import org.apache.helix.model.StateModelDefinition;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.ObjectReader;
import org.testng.Assert;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

public class TestZeroReplicaAvoidance extends BaseStageTest {

  @Test(dataProvider = "zeroReplicaInput")
  public void testZeroReplicaAvoidanceDuringRebalance(StateModelDefinition stateModelDef,
      List<String> instancePreferenceList, Map<String, String> currentStateMap,
      Map<String, List<Message>> pendingMessages, Map<String, String> expectedBestPossibleMap) {
    System.out
        .println("START TestDelayedAutoRebalancer at " + new Date(System.currentTimeMillis()));

    System.err.println("Test input: " + instancePreferenceList + ":" + currentStateMap + ":");

    int numNode = 6;
    Set<String> liveInstances = new HashSet<>();
    for (int i = 0; i < numNode; i++) {
      liveInstances.add("localhost_" + i);
    }

    IdealState is = new IdealState("test");
    is.setReplicas("3");
    Partition partition = new Partition("testPartition");
    DelayedAutoRebalancer rebalancer = new DelayedAutoRebalancer();
    CurrentStateOutput currentStateOutput = new CurrentStateOutput();
    for (String instance : currentStateMap.keySet()) {
      currentStateOutput.setCurrentState("test", partition, instance,
          currentStateMap.get(instance));
    }
    Set<String> allInstances = new HashSet<>(instancePreferenceList);
    allInstances.addAll(currentStateMap.keySet());
    if (pendingMessages != null) {
      for (String instance : allInstances) {
        List<Message> messages = pendingMessages.get(instance);
        if (messages != null) {
          for (Message message : messages) {
            currentStateOutput.setPendingMessage("test", partition, instance, message);
          }
        }
      }
    }
    Map<String, String> bestPossibleMap = rebalancer.computeBestPossibleStateForPartition(
        liveInstances, stateModelDef, instancePreferenceList, currentStateOutput,
        Collections.emptySet(), is, new ClusterConfig("TestCluster"), partition);
    Assert.assertEquals(bestPossibleMap, expectedBestPossibleMap,
        "Differs, get " + bestPossibleMap + "\nexpected: " + expectedBestPossibleMap
            + "\ncurrentState: " + currentStateMap + "\npreferenceList: " + instancePreferenceList);

    System.out
        .println("END TestBestPossibleStateCalcStage at " + new Date(System.currentTimeMillis()));
  }

  @DataProvider(name = "zeroReplicaInput")
  public Object[][] rebalanceStrategies() {
    List<Object[]> data = new ArrayList<>();
    data.addAll(loadTestInputs("TestDelayedAutoRebalancer.MasterSlave.json"));
    data.addAll(loadTestInputs("TestDelayedAutoRebalancer.OnlineOffline.json"));

    Object[][] ret = new Object[data.size()][];
    for (int i = 0; i < data.size(); i++) {
      ret[i] = data.get(i);
    }
    return ret;
  }

  private final String INPUT = "inputs";
  private final String CURRENT_STATE = "currentStates";
  private final String PENDING_MESSAGES = "pendingMessages";
  private final String BEST_POSSIBLE_STATE = "bestPossibleStates";
  private final String PREFERENCE_LIST = "preferenceList";
  private final String STATE_MODEL = "statemodel";

  public List<Object[]> loadTestInputs(String fileName) {
    List<Object[]> ret = null;
    InputStream inputStream = getClass().getClassLoader().getResourceAsStream(fileName);
    try {
      ObjectReader mapReader = new ObjectMapper().reader(Map.class);
      Map<String, Object> inputMaps = mapReader.readValue(inputStream);
      String stateModelName = (String) inputMaps.get(STATE_MODEL);

      StateModelDefinition stateModelDef =
          BuiltInStateModelDefinitions.valueOf(stateModelName).getStateModelDefinition();

      List<Map<String, Object>> inputs = (List<Map<String, Object>>) inputMaps.get(INPUT);
      ret = new ArrayList<>();
      for (Map<String, Object> inMap : inputs) {
        Map<String, String> currentStates = (Map<String, String>) inMap.get(CURRENT_STATE);
        Map<String, String> bestPossibleStates =
            (Map<String, String>) inMap.get(BEST_POSSIBLE_STATE);
        List<String> preferenceList = (List<String>) inMap.get(PREFERENCE_LIST);
        Map<String, String> pendingStates = (Map<String, String>) inMap.get(PENDING_MESSAGES);
        Map<String, List<Message>> pendingMessages = null;
        if (pendingStates != null) {
          Random r = new Random();
          pendingMessages = new HashMap<>();
          for (String instance : pendingStates.keySet()) {
            pendingMessages.put(instance, new ArrayList<>());
            Message m = new Message(new ZNRecord(UUID.randomUUID().toString()));
            m.setFromState(pendingStates.get(instance).split(":")[0]);
            m.setToState(pendingStates.get(instance).split(":")[1]);
            pendingMessages.get(instance).add(m);
          }
        }

        ret.add(new Object[] {
            stateModelDef, preferenceList, currentStates, pendingMessages, bestPossibleStates
        });
      }
    } catch (IOException e) {
      e.printStackTrace();
    }

    return ret;
  }
}
