/*
 * Copyright (c) 2014 DataTorrent, Inc. ALL Rights Reserved.
 *
 * Licensed 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 com.datatorrent.contrib.splunk;

import java.io.InputStream;
import javax.validation.constraints.NotNull;
import com.splunk.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.datatorrent.api.DefaultOutputPort;
import com.datatorrent.api.Context.OperatorContext;
import com.datatorrent.api.annotation.OutputPortFieldAnnotation;

import com.datatorrent.lib.db.AbstractStoreInputOperator;

/**
 * Base Splunk input adapter operator, which reads data from Splunk through its SPLUNK's API
 * and writes into output port(s).
 *
 * <p>
 * This is an abstract class. Sub-classes need to implement {@link #queryToRetrieveData()} and {@link #getTuple(Row)}.
 * </p>
 *
 * @since 1.0.4
 */
public abstract class AbstractSplunkInputOperator<T> extends AbstractStoreInputOperator<T, SplunkStore> {

  private static final Logger logger = LoggerFactory.getLogger(AbstractSplunkInputOperator.class);
  @NotNull
  protected String earliestTime;
  protected String latestTime;
  protected transient JobExportArgs exportArgs;
  protected transient InputStream exportSearch;
  protected transient MultiResultsReaderXml multiResultsReader;

  public void setEarliestTime(@NotNull String earliestTime) {
    this.earliestTime = earliestTime;
  }

  public void setLatestTime(@NotNull String latestTime) {
    this.latestTime = latestTime;
  }

  /**
   * Any concrete class has to override this method to convert a Value of an Event into Tuple.
   *
   * @param value a single value that has been read from a splunk event.
   * @return Tuple a tuples created from row which can be any Java object.
   */
  public abstract T getTuple(String value);

  /**
   * Any concrete class has to override this method to return the query string which will be used to
   * retrieve data from splunk.
   *
   * @return Query string
   */
  public abstract String queryToRetrieveData();

  /**
   * The output port that will emit tuple into DAG.
   */
  @OutputPortFieldAnnotation(name = "outputPort")
  public final transient DefaultOutputPort<T> outputPort = new DefaultOutputPort<T>();

  @Override
  public void setup(OperatorContext t1)
  {
    super.setup(t1);
    exportArgs = new JobExportArgs();
    exportArgs.setEarliestTime(earliestTime);
    exportArgs.setLatestTime(latestTime);
    exportArgs.setSearchMode(JobExportArgs.SearchMode.NORMAL);
  }

  /**
   * This executes the search query to retrieve result from splunk.
   * It then converts each event's value into tuple and emit that into output port.
   */
  @Override
  public void emitTuples()
  {
    String query = queryToRetrieveData();
    logger.debug(String.format("select statement: %s", query));

    try {
      exportSearch = store.getService().export(queryToRetrieveData(), exportArgs);
      multiResultsReader = new MultiResultsReaderXml(exportSearch);
      for (SearchResults searchResults : multiResultsReader)
      {
        for (Event event : searchResults) {
          for (String key: event.keySet()){
            if(key.contains("raw")){
              T tuple = getTuple(event.get(key));
              outputPort.emit(tuple);
            }
          }
        }
      }
      multiResultsReader.close();
    } catch (Exception e) {
      store.disconnect();
      throw new RuntimeException(String.format("Error while running query: %s", query), e);
    }
  }
}