/*
    * 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.kafka;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.NoSuchElementException;
  import java.util.Optional;
  
  import org.apache.kafka.common.record.TimestampType;
  import org.apache.gobblin.configuration.WorkUnitState;
  import org.apache.gobblin.kafka.client.ByteArrayBasedKafkaRecord;
  import org.apache.gobblin.kafka.client.KafkaConsumerRecord;
  import org.apache.gobblin.source.extractor.DataRecordException;
  import org.apache.gobblin.source.extractor.extract.kafka.KafkaExtractor;
  import org.wikimedia.gobblin.copy.Kafka1ConsumerClient;
  import org.wikimedia.gobblin.TimestampedRecord;
  
  
  import com.google.common.collect.ImmutableSet;
  
  import lombok.extern.slf4j.Slf4j;
  
  
  /**
   * Extracts {@link TimestampedRecord} records from Kafka using Kafka1 client.
   * The extracted record timestamp is set to the kafka record timestamp if the kafka
   * record timestamp-type is in the list of extracted-timestamp-types defined using
   * the property source.kafka.extract.timestampTypes (accepted values are CreateTime
   * and LogAppendTime, or unset-property). If the timestamp is not extracted from the
   * kafka record, it is set to current-timestamp if the state property
   * source.kafka.extract.timestamp.defaultCurrent is set to true, and is absent otherwise.
   * @param <P> The type of the deserialized payload from the kafka record.
   */
  @Slf4j
  public class Kafka1TimestampedRecordExtractor<P> extends KafkaExtractor<Object, Object> {
  
      public static final String EXTRACTED_TIMESTAMP_TYPES_KEY = "source.kafka.extract.timestampTypes";
      public static final String CURRENT_TIMESTAMP_AS_DEFAULT_KEY = "source.kafka.extract.timestamp.defaultCurrent";
  
      private final ImmutableSet<TimestampType> extractedTimestampTypes;
      private final boolean useCurrentTimestampAsDefault;
  
      public Kafka1TimestampedRecordExtractor(WorkUnitState state) {
          super(state);
          this.extractedTimestampTypes = getExtractedTimestampTypes(state);
          this.useCurrentTimestampAsDefault = getUseCurrentTimestampAsDefault(state);
      }
  
      /**
       * Uses state EXTRACTED_TIMESTAMP_TYPES_KEY property to construct a list
       * of {@link TimestampType} defining the types of kafka-timestamps that
       * will lead to extracted records having kafka timestamp set.
       * Accepted values are CreateTime and LogAppendTime, or unset-property (leading
       * to all records having the default timestamp).
       *
       * @return The {@link TimestampType} list, empty if the property is not present.
       * @Throws NoSuchElementException in case of invalid {@link TimestampType}
       * @throws IllegalArgumentException if {@link TimestampType} is not of accepted values
       */
      private ImmutableSet<TimestampType> getExtractedTimestampTypes(WorkUnitState state) {
          ImmutableSet.Builder<TimestampType> result = ImmutableSet.builder();
          if (state.contains(EXTRACTED_TIMESTAMP_TYPES_KEY)) {
              for (String timestampTypeName : state.getPropAsList(EXTRACTED_TIMESTAMP_TYPES_KEY)) {
                  TimestampType timestampType = TimestampType.forName(timestampTypeName);
                  if (timestampType == TimestampType.CREATE_TIME || timestampType == TimestampType.LOG_APPEND_TIME) {
                      result.add(timestampType);
                  } else {
                      throw new IllegalArgumentException("Invalid TimestampType to extract: " + timestampType +
                              ". Accepted values are CreateTime and/or LogAppendTime");
                  }
              }
          }
          return result.build();
      }
  
      /**
       * Uses state CURRENT_TIMESTAMP_AS_DEFAULT_KEY property to define if record timestamp
       * should be set to current-time if kafka timestamp can't be used (by opposition to be absent).
       *
       * @return The {@link TimestampType} list, empty if the property is not present.
       */
      private boolean getUseCurrentTimestampAsDefault(WorkUnitState state) throws NoSuchElementException {
          return  (state.contains(CURRENT_TIMESTAMP_AS_DEFAULT_KEY) &&
                 state.getPropAsBoolean(CURRENT_TIMESTAMP_AS_DEFAULT_KEY));
     }
 
     /**
      * We need to override this protected method as the kafka timestamp information is not
      * available in the {@link KafkaExtractor#decodeRecord(ByteArrayBasedKafkaRecord)} abstract method.
      */
     @Override
     protected TimestampedRecord<P> decodeKafkaMessage(KafkaConsumerRecord message) throws DataRecordException, IOException {
         if (message instanceof Kafka1ConsumerClient.Kafka1ConsumerRecord) {
             Kafka1ConsumerClient.Kafka1ConsumerRecord typedRecord = (Kafka1ConsumerClient.Kafka1ConsumerRecord)message;
             // if value is null then this is a bad record that is returned for further error handling, so raise an error
             if (typedRecord.getValue() == null) {
                 throw new DataRecordException("Could not decode Kafka record");
             }
 
             Optional<Long> timestamp = Optional.empty();
             if (extractedTimestampTypes.contains(typedRecord.getTimestampType())) {
                 timestamp = Optional.of(typedRecord.getTimestamp());
             } else if (useCurrentTimestampAsDefault) {
                 timestamp = Optional.of(System.currentTimeMillis());
             }
             return new TimestampedRecord(typedRecord.getValue(), timestamp);
         } else {
             throw new IllegalStateException(
                     "Unsupported KafkaConsumerRecord type. The record should be Kafka1ConsumerRecord but is " +
                     message.getClass().getCanonicalName());
         }
     }
 
     /**
      * Unreachable, as {@link KafkaExtractor#decodeKafkaMessage(KafkaConsumerRecord)} is override not to use this method.
      */
     @Override
     protected Object decodeRecord(ByteArrayBasedKafkaRecord kafkaConsumerRecord) throws IOException {
         throw new IllegalArgumentException("Could not decode Kafka record");
     }
 
     // TODO: Implement schema getter option (for events!)
     @Override
     public Object getSchema() {
         return null;
     }
 
 }