/*
 * 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.geode.kafka.sink;

import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import org.apache.kafka.connect.sink.SinkRecord;
import org.apache.kafka.connect.sink.SinkTask;
import org.geode.kafka.GeodeContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.geode.cache.Region;
import org.apache.geode.cache.RegionExistsException;
import org.apache.geode.cache.client.ClientRegionShortcut;


/**
 * TODO javaDoc
 * Currently force 1 region per task
 */
public class GeodeKafkaSinkTask extends SinkTask {

  private static final Logger logger = LoggerFactory.getLogger(GeodeKafkaSinkTask.class);

  private GeodeContext geodeContext;
  private int taskId;
  private Map<String, List<String>> topicToRegions;
  private Map<String, Region> regionNameToRegion;
  private boolean nullValuesMeansRemove = true;

  /**
   * {@inheritDoc}
   */
  @Override
  public String version() {
    // TODO
    return "unknown";
  }

  @Override
  public void start(Map<String, String> props) {
    try {
      GeodeSinkConnectorConfig geodeConnectorConfig = new GeodeSinkConnectorConfig(props);
      configure(geodeConnectorConfig);
      geodeContext = new GeodeContext();
      geodeContext.connectClient(geodeConnectorConfig.getLocatorHostPorts(),
          geodeConnectorConfig.getSecurityClientAuthInit(),
          geodeConnectorConfig.getSecurityUserName(), geodeConnectorConfig.getSecurityPassword(),
          geodeConnectorConfig.usesSecurity());
      regionNameToRegion = createProxyRegions(topicToRegions.values());
    } catch (Exception e) {
      logger.error("Unable to start sink task", e);
      throw e;
    }
  }

  void configure(GeodeSinkConnectorConfig geodeConnectorConfig) {
    logger.debug("GeodeKafkaSourceTask id:" + geodeConnectorConfig.getTaskId() + " starting");
    taskId = geodeConnectorConfig.getTaskId();
    topicToRegions = geodeConnectorConfig.getTopicToRegions();
    nullValuesMeansRemove = geodeConnectorConfig.getNullValuesMeanRemove();
  }

  // For tests only
  void setRegionNameToRegion(Map<String, Region> regionNameToRegion) {
    this.regionNameToRegion = regionNameToRegion;
  }

  @Override
  public void put(Collection<SinkRecord> records) {
    put(records, new HashMap());
  }

  void put(Collection<SinkRecord> records, Map<String, BatchRecords> batchRecordsMap) {
    // spin off a new thread to handle this operation? Downside is ordering and retries...
    for (SinkRecord record : records) {
      updateBatchForRegionByTopic(record, batchRecordsMap);
    }
    batchRecordsMap.entrySet().stream().forEach((entry) -> {
      String region = entry.getKey();
      BatchRecords batchRecords = entry.getValue();
      batchRecords.executeOperations(regionNameToRegion.get(region));
    });
  }

  private void updateBatchForRegionByTopic(SinkRecord sinkRecord,
      Map<String, BatchRecords> batchRecordsMap) {
    Collection<String> regionsToUpdate = topicToRegions.get(sinkRecord.topic());
    for (String region : regionsToUpdate) {
      updateBatchRecordsForRecord(sinkRecord, batchRecordsMap, region);
    }
  }

  private void updateBatchRecordsForRecord(SinkRecord record,
      Map<String, BatchRecords> batchRecordsMap, String region) {
    BatchRecords batchRecords = batchRecordsMap.get(region);
    if (batchRecords == null) {
      batchRecords = new BatchRecords();
      batchRecordsMap.put(region, batchRecords);
    }
    if (record.key() != null) {
      if (record.value() == null && nullValuesMeansRemove) {
        batchRecords.addRemoveOperation(record);
      } else {
        batchRecords.addUpdateOperation(record, nullValuesMeansRemove);
      }
    } else {
      // Invest in configurable auto key generator?
      logger.warn("Unable to push to Geode, missing key in record : " + record.value());
    }
  }

  private Map<String, Region> createProxyRegions(Collection<List<String>> regionNames) {
    List<String> flat = regionNames.stream().flatMap(List::stream).collect(Collectors.toList());
    return flat.stream().map(regionName -> createProxyRegion(regionName))
        .collect(Collectors.toMap(region -> region.getName(), region -> region));
  }

  private Region createProxyRegion(String regionName) {
    try {
      return geodeContext.getClientCache().createClientRegionFactory(ClientRegionShortcut.PROXY)
          .create(regionName);
    } catch (RegionExistsException e) {
      // Each task is a seperate parallel task controlled by kafka.
      return geodeContext.getClientCache().getRegion(regionName);
    }
  }

  @Override
  public void stop() {
    geodeContext.getClientCache().close(false);
  }

}