/**
 * 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.storm.kafka.trident;

import org.apache.storm.task.OutputCollector;
import org.apache.storm.topology.FailedException;
import org.apache.commons.lang.Validate;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.storm.kafka.trident.mapper.TridentTupleToKafkaMapper;
import org.apache.storm.kafka.trident.selector.KafkaTopicSelector;
import org.apache.storm.trident.operation.TridentCollector;
import org.apache.storm.trident.state.State;
import org.apache.storm.trident.tuple.TridentTuple;

import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

public class TridentKafkaState implements State {
    private static final Logger LOG = LoggerFactory.getLogger(TridentKafkaState.class);

    private KafkaProducer producer;
    private OutputCollector collector;

    private TridentTupleToKafkaMapper mapper;
    private KafkaTopicSelector topicSelector;

    public TridentKafkaState withTridentTupleToKafkaMapper(TridentTupleToKafkaMapper mapper) {
        this.mapper = mapper;
        return this;
    }

    public TridentKafkaState withKafkaTopicSelector(KafkaTopicSelector selector) {
        this.topicSelector = selector;
        return this;
    }

    @Override
    public void beginCommit(Long txid) {
        LOG.debug("beginCommit is Noop.");
    }

    @Override
    public void commit(Long txid) {
        LOG.debug("commit is Noop.");
    }

    public void prepare(Properties options) {
        Validate.notNull(mapper, "mapper can not be null");
        Validate.notNull(topicSelector, "topicSelector can not be null");
        producer = new KafkaProducer(options);
    }

    public void updateState(List<TridentTuple> tuples, TridentCollector collector) {
        String topic = null;
        try {
            List<Future<RecordMetadata>> futures = new ArrayList<>(tuples.size());
            for (TridentTuple tuple : tuples) {
                topic = topicSelector.getTopic(tuple);

                if(topic != null) {
                    Future<RecordMetadata> result = producer.send(new ProducerRecord(topic,
                            mapper.getKeyFromTuple(tuple), mapper.getMessageFromTuple(tuple)));
                    futures.add(result);
                } else {
                    LOG.warn("skipping key = " + mapper.getKeyFromTuple(tuple) + ", topic selector returned null.");
                }
            }

            List<ExecutionException> exceptions = new ArrayList<>(futures.size());
            for (Future<RecordMetadata> future : futures) {
                try {
                    future.get();
                } catch (ExecutionException e) {
                    exceptions.add(e);
                }
            }

            if(exceptions.size() > 0){
                String errorMsg = "Could not retrieve result for messages " + tuples + " from topic = " + topic 
                        + " because of the following exceptions: \n";
                for (ExecutionException exception : exceptions) {
                    errorMsg = errorMsg + exception.getMessage() + "\n";
                }
                LOG.error(errorMsg);
                throw new FailedException(errorMsg);
            }
        } catch (Exception ex) {
            String errorMsg = "Could not send messages " + tuples + " to topic = " + topic;
            LOG.warn(errorMsg, ex);
            throw new FailedException(errorMsg, ex);
        }
    }
}
