/**
 * 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.hive.trident;

import org.apache.storm.trident.operation.TridentCollector;
import org.apache.storm.trident.state.State;
import org.apache.storm.trident.tuple.TridentTuple;
import org.apache.storm.task.IMetricsContext;
import org.apache.storm.topology.FailedException;
import org.apache.storm.hive.common.HiveWriter;
import org.apache.hive.hcatalog.streaming.*;
import org.apache.storm.hive.common.HiveOptions;
import org.apache.storm.hive.common.HiveUtils;
import org.apache.hadoop.security.UserGroupInformation;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.Timer;
import java.util.TimerTask;
import java.util.Map.Entry;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;

public class HiveState implements State {
    private static final Logger LOG = LoggerFactory.getLogger(HiveState.class);
    private HiveOptions options;
    private Integer currentBatchSize;
    private ExecutorService callTimeoutPool;
    private transient Timer heartBeatTimer;
    private AtomicBoolean timeToSendHeartBeat = new AtomicBoolean(false);
    private Boolean sendHeartBeat = true;
    private UserGroupInformation ugi = null;
    private Boolean kerberosEnabled = false;
    private Map<HiveEndPoint, HiveWriter> allWriters;
    private boolean tokenAuthEnabled;

    public HiveState(HiveOptions options) {
        this.options = options;
        this.currentBatchSize = 0;
    }


    @Override
    public void beginCommit(Long txId) {
    }

    @Override
    public void commit(Long txId) {
    }

    public void prepare(Map conf, IMetricsContext metrics, int partitionIndex, int numPartitions)  {
        try {
            tokenAuthEnabled = HiveUtils.isTokenAuthEnabled(conf);
            try {
                ugi = HiveUtils.authenticate(tokenAuthEnabled, options.getKerberosKeytab(), options.getKerberosPrincipal());
            } catch(HiveUtils.AuthenticationFailed ex) {
                LOG.error("Hive kerberos authentication failed " + ex.getMessage(), ex);
                throw new IllegalArgumentException(ex);
            }

            allWriters = new ConcurrentHashMap<HiveEndPoint,HiveWriter>();
            String timeoutName = "hive-bolt-%d";
            this.callTimeoutPool = Executors.newFixedThreadPool(1,
                                                                new ThreadFactoryBuilder().setNameFormat(timeoutName).build());
            heartBeatTimer= new Timer();
            setupHeartBeatTimer();
        } catch(Exception e) {
            LOG.warn("unable to make connection to hive ",e);
        }
    }

    public void updateState(List<TridentTuple> tuples, TridentCollector collector) {
        try {
            writeTuples(tuples);
        } catch (Exception e) {
            abortAndCloseWriters();
            LOG.warn("hive streaming failed.",e);
            throw new FailedException(e);
        }
    }

    private void writeTuples(List<TridentTuple> tuples)
        throws Exception {
        for (TridentTuple tuple : tuples) {
            List<String> partitionVals = options.getMapper().mapPartitions(tuple);
            HiveEndPoint endPoint = HiveUtils.makeEndPoint(partitionVals, options);
            HiveWriter writer = getOrCreateWriter(endPoint);
            writer.write(options.getMapper().mapRecord(tuple));
            currentBatchSize++;
            if(currentBatchSize >= options.getBatchSize()) {
                flushAllWriters();
                currentBatchSize = 0;
            }
        }
    }

    private void abortAndCloseWriters() {
        try {
            sendHeartBeat = false;
            abortAllWriters();
            closeAllWriters();
        }  catch(Exception ie) {
            LOG.warn("unable to close hive connections. ", ie);
        }
    }

    /**
     * Abort current Txn on all writers
     */
    private void abortAllWriters() throws InterruptedException, StreamingException, HiveWriter.TxnBatchFailure {
        for (Entry<HiveEndPoint,HiveWriter> entry : allWriters.entrySet()) {
            entry.getValue().abort();
        }
    }


    /**
     * Closes all writers and remove them from cache
     * @return number of writers retired
     */
    private void closeAllWriters() throws InterruptedException, IOException {
        //1) Retire writers
        for (Entry<HiveEndPoint,HiveWriter> entry : allWriters.entrySet()) {
            entry.getValue().close();
        }
        //2) Clear cache
        allWriters.clear();
    }

    private void setupHeartBeatTimer() {
        if(options.getHeartBeatInterval()>0) {
            heartBeatTimer.schedule(new TimerTask() {
                    @Override
                    public void run() {
                        try {
                            if (sendHeartBeat) {
                                LOG.debug("Start sending heartbeat on all writers");
                                sendHeartBeatOnAllWriters();
                                setupHeartBeatTimer();
                            }
                        } catch (Exception e) {
                            LOG.warn("Failed to heartbeat on HiveWriter ", e);
                        }
                    }
                }, options.getHeartBeatInterval() * 1000);
        }
    }

    private void flushAllWriters()
        throws HiveWriter.CommitFailure, HiveWriter.TxnBatchFailure, HiveWriter.TxnFailure, InterruptedException {
        for(HiveWriter writer: allWriters.values()) {
            writer.flush(true);
        }
    }

    private void sendHeartBeatOnAllWriters() throws InterruptedException {
        for (HiveWriter writer : allWriters.values()) {
            writer.heartBeat();
        }
    }

    private HiveWriter getOrCreateWriter(HiveEndPoint endPoint)
        throws HiveWriter.ConnectFailure, InterruptedException {
        try {
            HiveWriter writer = allWriters.get( endPoint );
            if( writer == null ) {
                LOG.info("Creating Writer to Hive end point : " + endPoint);
                writer = HiveUtils.makeHiveWriter(endPoint, callTimeoutPool, ugi, options, tokenAuthEnabled);
                if(allWriters.size() > (options.getMaxOpenConnections() - 1)){
                    int retired = retireIdleWriters();
                    if(retired==0) {
                        retireEldestWriter();
                    }
                }
                allWriters.put(endPoint, writer);
            }
            return writer;
        } catch (HiveWriter.ConnectFailure e) {
            LOG.error("Failed to create HiveWriter for endpoint: " + endPoint, e);
            throw e;
        }

    }



    /**
     * Locate writer that has not been used for longest time and retire it
     */
    private void retireEldestWriter() {
        long oldestTimeStamp = System.currentTimeMillis();
        HiveEndPoint eldest = null;
        for (Entry<HiveEndPoint,HiveWriter> entry : allWriters.entrySet()) {
            if(entry.getValue().getLastUsed() < oldestTimeStamp) {
                eldest = entry.getKey();
                oldestTimeStamp = entry.getValue().getLastUsed();
            }
        }
        try {
            LOG.info("Closing least used Writer to Hive end point : " + eldest);
            allWriters.remove(eldest).flushAndClose();
        } catch (IOException e) {
            LOG.warn("Failed to close writer for end point: " + eldest, e);
        } catch (InterruptedException e) {
            LOG.warn("Interrupted when attempting to close writer for end point: " + eldest, e);
            Thread.currentThread().interrupt();
        } catch (Exception e) {
            LOG.warn("Interrupted when attempting to close writer for end point: " + eldest, e);
        }
    }

    /**
     * Locate all writers past idle timeout and retire them
     * @return number of writers retired
     */
    private int retireIdleWriters() {
        int count = 0;
        long now = System.currentTimeMillis();
        ArrayList<HiveEndPoint> retirees = new ArrayList<HiveEndPoint>();

        //1) Find retirement candidates
        for (Entry<HiveEndPoint,HiveWriter> entry : allWriters.entrySet()) {
            if(now - entry.getValue().getLastUsed() > options.getIdleTimeout()) {
                ++count;
                retirees.add(entry.getKey());
            }
        }
        //2) Retire them
        for(HiveEndPoint ep : retirees) {
            try {
                LOG.info("Closing idle Writer to Hive end point : {}", ep);
                allWriters.remove(ep).flushAndClose();
            } catch (IOException e) {
                LOG.warn("Failed to close writer for end point: {}. Error: "+ ep, e);
            } catch (InterruptedException e) {
                LOG.warn("Interrupted when attempting to close writer for end point: " + ep, e);
                Thread.currentThread().interrupt();
            } catch (Exception e) {
                LOG.warn("Interrupted when attempting to close writer for end point: " + ep, e);
            }
        }
        return count;
    }

    public void cleanup() {
        for (Entry<HiveEndPoint, HiveWriter> entry : allWriters.entrySet()) {
            try {
                sendHeartBeat = false;
                HiveWriter w = entry.getValue();
                LOG.info("Flushing writer to {}", w);
                w.flush(false);
                LOG.info("Closing writer to {}", w);
                w.close();
            } catch (Exception ex) {
                LOG.warn("Error while closing writer to " + entry.getKey() +
                         ". Exception follows.", ex);
                if (ex instanceof InterruptedException) {
                    Thread.currentThread().interrupt();
                }
            }
        }

        ExecutorService toShutdown[] = {callTimeoutPool};
        for (ExecutorService execService : toShutdown) {
            execService.shutdown();
            try {
                while (!execService.isTerminated()) {
                    execService.awaitTermination(
                                                 options.getCallTimeOut(), TimeUnit.MILLISECONDS);
                }
            } catch (InterruptedException ex) {
                LOG.warn("shutdown interrupted on " + execService, ex);
            }
        }
        callTimeoutPool = null;
    }

}
