/*
    * 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.wikimedia.gobblin.utils;
  
  import static java.util.Locale.ENGLISH;
  
  import java.io.IOException;
  import java.text.SimpleDateFormat;
  import java.util.Collection;
  import java.util.List;
  import java.util.stream.Collectors;
  
  import org.joda.time.DateTime;
  
  import com.fasterxml.jackson.databind.JsonNode;
  import com.fasterxml.jackson.databind.ObjectMapper;
  
  import lombok.extern.slf4j.Slf4j;
  
  
  /**
   * A utility class parsing JSON from byte[] ans extracting a timestamp from the data.
   *
   * The class provides static functions to initialize both the timestamp and the
   * timestamp-format fields from a WriterPartitioner.
   *
   * If a record doesn't contain the specified field, or if no field is specified, the current timestamp will be used.
   *
   * Accepted formats are:
   * <ul>
   * <li>unix (same as unix_seconds)</li>
   * <li>unix_seconds</li>
   * <li>unix_milliseconds</li>
   * <li>ISO_8601</li>
   * <li>CUSTOM - Using the timestampCustomFormat parameter (can be empty for other values)</li>
   * </ul>
   *
   */
  @Slf4j
  public class JsonStringTimestampExtractor {
  
      private final List<String> timestampPointers;
      // Those two fields can't be made final due to initialization in try/catch
      private SimpleDateFormat timestampParser;
      private TimestampFormat timestampFormat;
      private final ObjectMapper cachingMapper;
  
      public JsonStringTimestampExtractor(Collection<String> timestampPointers, String timestampFormat) {
          // Convert the timestampPointer column from JSON to Jackson syntax
          this.timestampPointers = timestampPointers.stream()
                  .map(s -> "/" + s.replace('.', '/'))
                  .collect(Collectors.toList());
          this.cachingMapper = new ObjectMapper();
          try {
              this.timestampFormat = TimestampFormat.valueOf(timestampFormat);
              this.timestampParser = null;
          } catch (IllegalArgumentException iae) {
              this.timestampFormat = TimestampFormat.CUSTOM;
              this.timestampParser = new SimpleDateFormat(timestampFormat, ENGLISH);
          } catch (NullPointerException npe) {
              throw new IllegalArgumentException("Parameter timestampFormat shouldn't be null", npe);
          }
      }
  
      public long getRecordTimestamp(String payload) {
          JsonNode root;
          long ifNotFound = System.currentTimeMillis();
          try {
              root = cachingMapper.readTree(payload);
          } catch (IOException ie) {
              log.warn("Couldn't parse the json payload for timestamp extraction: {}", payload, ie);
              return ifNotFound;
          }
          for (String timestampPointer: timestampPointers) {
              try {
                  JsonNode match = root.at(timestampPointer);
  
                  if (match.canConvertToLong()) {
                      long found = match.asLong();
                      switch (timestampFormat) {
                          case unix:
                          case unix_seconds:
                              return found * 1000L;
                         case unix_milliseconds:
                             return found;
                     }
                 } else if (match.isTextual()) {
                     String found = match.asText();
                     switch (timestampFormat) {
                         case ISO_8601:
                             return new DateTime(found).getMillis();
                         case CUSTOM:
                             return timestampParser.parse(found).getTime();
                     }
                 }
                 log.warn("No timestamp extracted from json payload: {}", payload);
             } catch (Exception ex) {
                 log.warn("Failed to extract timestamp from json payload: {}", payload, ex);
             }
         }
         return ifNotFound;
     }
 
     public enum TimestampFormat {
         unix,
         unix_seconds,
         unix_milliseconds,
         ISO_8601,
         CUSTOM
     }
 
 }