/*******************************************************************************
 * Copyright (c) 2008, 2021 SAP AG, IBM Corporation and others
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *    SAP AG - initial API and implementation
 *    IBM Corporation - enhancements and fixes
 *    James Livingston - expose collection utils as API
 *******************************************************************************/
package org.eclipse.mat.inspections.collections;

import java.util.Arrays;

import org.eclipse.mat.SnapshotException;
import org.eclipse.mat.collect.HashMapIntLong;
import org.eclipse.mat.collect.HashMapIntObject;
import org.eclipse.mat.inspections.collectionextract.CollectionExtractionUtils;
import org.eclipse.mat.inspections.collectionextract.ExtractedMap;
import org.eclipse.mat.inspections.collectionextract.IMapExtractor;
import org.eclipse.mat.internal.Messages;
import org.eclipse.mat.internal.collectionextract.HashMapCollectionExtractor;
import org.eclipse.mat.query.IQuery;
import org.eclipse.mat.query.IResult;
import org.eclipse.mat.query.annotations.Argument;
import org.eclipse.mat.query.annotations.CommandName;
import org.eclipse.mat.query.annotations.HelpUrl;
import org.eclipse.mat.query.annotations.Icon;
import org.eclipse.mat.query.quantize.Quantize;
import org.eclipse.mat.snapshot.ISnapshot;
import org.eclipse.mat.snapshot.extension.Subjects;
import org.eclipse.mat.snapshot.model.IClass;
import org.eclipse.mat.snapshot.model.IObject;
import org.eclipse.mat.snapshot.query.IHeapObjectArgument;
import org.eclipse.mat.snapshot.query.RetainedSizeDerivedData;
import org.eclipse.mat.util.IProgressListener;
import org.eclipse.mat.util.MessageUtil;

@CommandName("map_collision_ratio")
@Icon("/META-INF/icons/map_collision.gif")
@HelpUrl("/org.eclipse.mat.ui.help/tasks/analyzingjavacollectionusage.html")
@Subjects({"java.util.AbstractMap",
    "java.util.jar.Attributes",
    "java.util.Dictionary",
    "java.lang.ThreadLocal$ThreadLocalMap",
    "java.util.concurrent.ConcurrentHashMap$Segment",
    "java.util.concurrent.ConcurrentHashMap$CollectionView",
    "java.util.Collections$SynchronizedMap",
    "java.util.Collections$UnmodifiableMap",
    "java.util.Collections$CheckedMap",
    "java.util.Collections$EmptyMap",
    "java.util.ResourceBundle",
    "java.awt.RenderingHints",
    "sun.awt.WeakIdentityHashMap",
    "javax.script.SimpleBindings",
    "javax.management.openmbean.TabularDataSupport",
    "com.ibm.jvm.util.HashMapRT",
    "com.sap.engine.lib.util.AbstractDataStructure",
    "org.eclipse.mat.collect.HashMapIntLong",
    "org.eclipse.mat.collect.HashMapIntObject",
    "org.eclipse.mat.collect.HashMapLongObject",
    "org.eclipse.mat.collect.HashMapObjectLong",

    // Sometimes useful to see collision ratio of a HashSet
    "java.util.HashSet",
    "java.util.Collections$SetFromMap",
    "java.util.Properties$EntrySet",
    "java.util.Collections$EmptySet",
})
public class MapCollisionRatioQuery implements IQuery
{

    @Argument
    public ISnapshot snapshot;

    @Argument(flag = Argument.UNFLAGGED)
    public IHeapObjectArgument objects;

    @Argument(isMandatory = false)
    public int segments = 5;

    @Argument(isMandatory = false)
    public String collection;

    @Argument(isMandatory = false)
    public String size_attribute;

    @Argument(isMandatory = false)
    public String array_attribute;

    private static class Result
    {
        final double ratio;
        final long used;
        public Result(double ratio, long used)
        {
            this.ratio = ratio;
            this.used = used;
        }
    }
    public IResult execute(IProgressListener listener) throws Exception
    {
        listener.subTask(Messages.MapCollisionRatioQuery_CalculatingCollisionRatios);

        // create frequency distribution
        Quantize.Builder builder = Quantize.linearFrequencyDistribution(
                        Messages.MapCollisionRatioQuery_Column_CollisionRatio, 0, 1, (double) 1 / (double) segments);
        builder.column(Messages.MapCollisionRatioQuery_Column_NumObjects, Quantize.COUNT);
        builder.column(Messages.Column_ShallowHeap, Quantize.SUM_BYTES);
        builder.addDerivedData(RetainedSizeDerivedData.APPROXIMATE);
        Quantize quantize = builder.build();

        IMapExtractor specificExtractor = new HashMapCollectionExtractor(size_attribute, array_attribute, null, null);
        final long LIMIT = 20;
        HashMapIntLong exceptions = new HashMapIntLong();
        int counter = 0;
        IClass type = null;
        for (int[] objectIds : objects)
        {
            HashMapIntObject<Result> resultMap = null;
            int sortedObjs[] = objectIds;
            int prev = Integer.MIN_VALUE;
            for (int objectId : objectIds)
            {
                if (objectId < prev)
                {
                    sortedObjs = objectIds.clone();
                    Arrays.sort(sortedObjs);
                    resultMap = new HashMapIntObject<Result>();
                    break;
                }
                prev = objectId;
            }
            for (int objectId : sortedObjs)
            {
                if (listener.isCanceled())
                    break;

                IObject obj = snapshot.getObject(objectId);
                if (counter++ % 1000 == 0 && !obj.getClazz().equals(type))
                {
                    type = obj.getClazz();
                    listener.subTask(Messages.MapCollisionRatioQuery_CalculatingCollisionRatios + "\n" + type.getName()); //$NON-NLS-1$
                }
                try
                {
                    ExtractedMap coll = CollectionExtractionUtils.extractMap(obj, collection, specificExtractor);

                    if (coll != null)
                    {
                        /*
                         * @FIXME - shouldn't really count maps without a collision ratio
                         * but current tests presume TreeSet/TreeMap have one.
                         */
                        if (coll.hasCollisionRatio() || true)
                        {
                            Double collisionRatio = coll.getCollisionRatio();
                            if (collisionRatio == null)
                                collisionRatio = 0.0;
                            if (resultMap != null)
                                resultMap.put(objectId, new Result(collisionRatio, coll.getUsedHeapSize()));
                            else
                                quantize.addValue(objectId, collisionRatio, null, coll.getUsedHeapSize());
                        }
                    }
                }
                catch (RuntimeException | SnapshotException e)
                {
                    int classId = obj.getClazz().getObjectId();
                    if (!exceptions.containsKey(classId))
                    {
                        exceptions.put(classId, 0);
                    }
                    long c =  exceptions.get(classId);
                    exceptions.put(classId, c + 1);
                    if (c < LIMIT)
                    {
                        listener.sendUserMessage(
                                        IProgressListener.Severity.INFO,
                                        MessageUtil.format(Messages.MapCollisionRatioQuery_IgnoringCollection,
                                                        obj.getTechnicalName()), e);
                    }
                }
            }
            if (resultMap != null)
            {
                for (int objectId : objectIds)
                {
                    if (resultMap.containsKey(objectId))
                    {
                        Result r = resultMap.get(objectId);
                        quantize.addValue(objectId, r.ratio, null, r.used);
                    }
                }
            }
            if (listener.isCanceled())
                break;
        }

        return quantize.getResult();
    }
}