/**
 * 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.apex.malhar.contrib.apachelog;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import javax.validation.constraints.NotNull;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.apex.malhar.lib.logs.InformationExtractor;

/**
 * An implementation of InformationExtractor that extracts the time stamp in milliseconds from epoch from an arbitrary date string.
 * <p>
 * @displayName Timestamp Extractor
 * @category Output
 * @tags timestamp, date, extraction
 * @since 0.9.4
 */
public class TimestampExtractor implements InformationExtractor
{
  private static final Logger LOG = LoggerFactory.getLogger(GeoIPExtractor.class);
  private static final long serialVersionUID = 201404221817L;
  @NotNull
  private String dateFormatString;
  private transient DateFormat dateFormat;  // date format is not serializable

  public void setDateFormatString(String dateFormatString)
  {
    this.dateFormatString = dateFormatString;
  }

  @Override
  public void setup()
  {
    dateFormat = new SimpleDateFormat(dateFormatString);
  }

  @Override
  public void teardown()
  {
  }

  @Override
  public Map<String, Object> extractInformation(Object value)
  {
    Map<String, Object> m = new HashMap<String, Object>();
    try {
      Date date = dateFormat.parse((String)value);
      m.put("timestamp", date.getTime());
    } catch (ParseException ex) {
      LOG.error("Error parsing \"{}\" to timestamp using \"{}\":", value, dateFormatString, ex);
    }
    return m;
  }

}