com.gs.fw.common.mithra.cacheloader.DateClusterCreator Maven / Gradle / Ivy

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/*
 Copyright 2016 Goldman Sachs.
 Licensed 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.
 */
// Portions copyright Hiroshi Ito. Licensed under Apache 2.0 license

package com.gs.fw.common.mithra.cacheloader;


import org.eclipse.collections.impl.list.mutable.FastList;
import org.joda.time.DateTime;
import org.joda.time.Days;

import java.sql.Timestamp;
import java.util.Collections;
import java.util.List;

public class DateClusterCreator
{
    private static final int MAX_DISTANCE = 5;

    public static List createMultiDateClusters(List businessDates)
    {
        Collections.sort(businessDates);
        return new DateClusterCreatorHelper(MAX_DISTANCE).create(businessDates);
    }

    public static List createSingleDateClusters(List businessDates)
    {
        Collections.sort(businessDates);
        List dateClusters = FastList.newList();
        for (Timestamp businessDate : businessDates)
        {
            dateClusters.add(new DateCluster(businessDate));
        }
        return dateClusters;
    }

    private static class DateClusterCreatorHelper
    {
        private final List dateClusters = FastList.newList();
        private final int maxDistance;

        private DateClusterCreatorHelper(int maxDistance)
        {
            this.maxDistance = maxDistance;
        }

        private List create(List businessDates)
        {
            if (businessDates != null && !businessDates.isEmpty())
            {
                List dateTimes = this.toDateTimes(businessDates);
                this.createFromDateTimes(dateTimes);
            }
            return this.dateClusters;
        }

        private List toDateTimes(List businessDates)
        {
            List dateTimes = FastList.newList(businessDates.size());
            for (Timestamp businessDate : businessDates)
            {
                dateTimes.add(new DateTime(businessDate));
            }
            return dateTimes;
        }

        private void createFromDateTimes(List sortedDateTimes)
        {
            List datesForCurrentCluster = FastList.newListWith(sortedDateTimes.remove(0));
            for (DateTime nextDateTime : sortedDateTimes)
            {
                if (this.isPartOfCurrentCluster(datesForCurrentCluster, nextDateTime))
                {
                    datesForCurrentCluster.add(nextDateTime);
                }
                else
                {
                    this.createCluster(datesForCurrentCluster);
                    datesForCurrentCluster = FastList.newListWith(nextDateTime);
                }
            }
            this.createCluster(datesForCurrentCluster);
        }

        private void createCluster(List datesForCluster)
        {
            List businessDates = FastList.newList(datesForCluster.size());
            for (DateTime dateTime : datesForCluster)
            {
                businessDates.add(toTimestamp(dateTime));
            }
            this.dateClusters.add(new DateCluster(businessDates));
        }

        private boolean isPartOfCurrentCluster(List datesForCurrentCluster, DateTime nextDateTime)
        {
            return Days.daysBetween(datesForCurrentCluster.get(datesForCurrentCluster.size() - 1), nextDateTime).getDays() <= this.maxDistance;
        }

        private static Timestamp toTimestamp(DateTime dateTime)
        {
            return new Timestamp(dateTime.getMillis());
        }
    }
}