/*
 * 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.eagle.hadoop.queue.crawler;

import org.apache.eagle.common.DateTimeUtil;
import org.apache.eagle.dataproc.impl.storm.ValuesArray;
import org.apache.eagle.hadoop.queue.common.HadoopClusterConstants;
import org.apache.eagle.hadoop.queue.common.HadoopClusterConstants.AggregateFunc;
import org.apache.eagle.hadoop.queue.common.HadoopClusterConstants.DataSource;
import org.apache.eagle.hadoop.queue.common.HadoopClusterConstants.DataType;
import org.apache.eagle.hadoop.queue.common.HadoopClusterConstants.MetricName;
import org.apache.eagle.hadoop.queue.model.cluster.ClusterMetrics;
import org.apache.eagle.hadoop.queue.storm.HadoopQueueMessageId;
import org.apache.eagle.log.entity.GenericMetricEntity;

import backtype.storm.spout.SpoutOutputCollector;
import org.apache.commons.lang3.builder.HashCodeBuilder;
import java.util.*;
import java.util.stream.Collectors;

public class ClusterMetricsParseListener {

    private String site;
    private SpoutOutputCollector collector;

    private long maxTimestamp;
    private Map<MetricKey, GenericMetricEntity> clusterMetricEntities = new HashMap<>();
    private Map<MetricKey, Integer> clusterMetricCounts = new HashMap<>();

    private static final long AGGREGATE_INTERVAL = DateTimeUtil.ONEMINUTE;
    private static final long HOLD_TIME_WINDOW = 2 * DateTimeUtil.ONEMINUTE;

    public ClusterMetricsParseListener(String site, SpoutOutputCollector collector) {
        reset();
        this.site = site;
        this.collector = collector;
    }

    private void createMetric(String metricName, long timestamp, double value, HadoopClusterConstants.AggregateFunc aggFunc) {
        if (timestamp > maxTimestamp) {
            maxTimestamp = timestamp;
        }
        timestamp = timestamp / AGGREGATE_INTERVAL * AGGREGATE_INTERVAL;
        MetricKey key = new MetricKey(metricName, timestamp);
        GenericMetricEntity entity = clusterMetricEntities.get(key);
        if (entity == null) {
            entity = new GenericMetricEntity();
            entity.setTags(buildMetricTags());
            entity.setTimestamp(timestamp);
            entity.setPrefix(metricName);
            entity.setValue(new double[] {0.0});
            clusterMetricEntities.put(key, entity);
        }
        if (clusterMetricCounts.get(key) == null) {
            clusterMetricCounts.put(key, 0);
        }
        updateEntityAggValue(entity, aggFunc, value, clusterMetricCounts.get(key));
        clusterMetricCounts.put(key, clusterMetricCounts.get(key) + 1);
    }

    public void onMetric(ClusterMetrics metrics, long currentTimestamp) {
        createMetric(MetricName.HADOOP_CLUSTER_NUMPENDING_JOBS, currentTimestamp, metrics.getAppsPending(), AggregateFunc.MAX);
        createMetric(MetricName.HADOOP_CLUSTER_ALLOCATED_MEMORY, currentTimestamp, metrics.getAllocatedMB(), AggregateFunc.AVG);
        createMetric(MetricName.HADOOP_CLUSTER_TOTAL_MEMORY, currentTimestamp, metrics.getTotalMB(), AggregateFunc.MAX);
        createMetric(MetricName.HADOOP_CLUSTER_AVAILABLE_MEMORY, currentTimestamp, metrics.getAvailableMB(), AggregateFunc.AVG);
        createMetric(MetricName.HADOOP_CLUSTER_RESERVED_MEMORY, currentTimestamp, metrics.getReservedMB(), AggregateFunc.AVG);
        createMetric(MetricName.HADOOP_CLUSTER_ALLOCATED_VIRTUAL_CORES, currentTimestamp, metrics.getAllocatedVirtualCores(), AggregateFunc.MAX);
    }

    public void flush() {
        HadoopQueueMessageId messageId = new HadoopQueueMessageId(DataType.METRIC, DataSource.CLUSTER_METRIC, System.currentTimeMillis());
        List<GenericMetricEntity> metrics = new ArrayList<>(clusterMetricEntities.values());
        this.collector.emit(new ValuesArray(DataType.METRIC.name(), metrics), messageId);
        reset();
    }

    private void reset() {
        maxTimestamp = 0;
        clearOldCache();
    }

    private void clearOldCache() {
        List<MetricKey> removedkeys = clusterMetricEntities.keySet().stream().filter(key -> key.createTime < maxTimestamp - HOLD_TIME_WINDOW).collect(Collectors.toList());

        for (MetricKey key : removedkeys) {
            clusterMetricEntities.remove(key);
        }
    }

    private Map<String, String> buildMetricTags() {
        Map<String, String> tags = new HashMap<String, String>();
        tags.put(HadoopClusterConstants.TAG_SITE, site);
        return tags;
    }

    private void updateEntityAggValue(GenericMetricEntity entity,
                                      HadoopClusterConstants.AggregateFunc aggFunc,
                                      double value,
                                      double count) {
        double lastValue = entity.getValue()[0];
        switch (aggFunc) {
            case MAX:
                entity.setValue(new double[] {Math.max(lastValue, value)});
                return;
            case AVG:
                long avgValue = (long) ((lastValue * count + value) / (count + 1));
                entity.setValue(new double[] {avgValue});
                return;
            default:
                throw new IllegalArgumentException("Illegal aggregation function: " + aggFunc);
        }
    }

    private class MetricKey {
        String metricName;
        Long createTime;

        public MetricKey(String metricName, Long timestamp) {
            this.metricName = metricName;
            this.createTime = timestamp;
        }

        public boolean equals(Object obj) {
            if (obj instanceof MetricKey) {
                MetricKey key = (MetricKey) obj;
                if (key == null) {
                    return false;
                }
                return Objects.equals(metricName, key.metricName) & Objects.equals(createTime, key.createTime);
            }
            return false;
        }

        public int hashCode() {
            return new HashCodeBuilder().append(metricName).append(createTime).toHashCode();
        }

    }
}
