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/**
 * Copyright (C) 2014 Dasasian ([email protected])
 *
 * 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.
 */
package com.dasasian.chok.util;

import java.util.*;

public class CollectionUtil {

    // TODO jz: avoid with bidi map?
    public static  Map> invertListMap(Map> key2ValuesMap) {
        One2ManyListMap value2KeysMap = new One2ManyListMap<>();
        for (K shardName : key2ValuesMap.keySet()) {
            List nodes = key2ValuesMap.get(shardName);
            for (V node : nodes) {
                value2KeysMap.add(node, shardName);
            }
        }
        return value2KeysMap.asMap();
    }

    public static List getListOfAdded(final Collection oldList, final Collection updatedList) {
        final List addedEntriesList = new ArrayList<>();
        extractAddedEntries(oldList, updatedList, addedEntriesList);
        return addedEntriesList;
    }

    public static Set getSetOfAdded(final Collection oldSet, final Collection updatedSet) {
        final Set addedEntriesSet = new HashSet<>();
        extractAddedEntries(oldSet, updatedSet, addedEntriesSet);
        return addedEntriesSet;
    }

    public static List getListOfRemoved(final Collection oldList, final Collection updatedList) {
        final List removedEntriesList = new ArrayList<>();
        extractRemovedEntries(oldList, updatedList, removedEntriesList);
        return removedEntriesList;
    }

    public static Set getSetOfRemoved(final Collection oldSet, final Collection updatedSet) {
        final Set removedEntriesSet = new HashSet<>();
        extractRemovedEntries(oldSet, updatedSet, removedEntriesSet);
        return removedEntriesSet;
    }

    private static void extractAddedEntries(final Collection oldCollection, final Collection updatedCollection, final Collection addedEntriesCollection) {
        for (final String entry : updatedCollection) {
            if (!oldCollection.contains(entry)) {
                addedEntriesCollection.add(entry);
            }
        }
    }

    private static void extractRemovedEntries(final Collection oldCollection, final Collection updatedCollection, final Collection removedEntriesCollection) {
        for (final String string : oldCollection) {
            if (!updatedCollection.contains(string)) {
                removedEntriesCollection.add(string);
            }
        }
    }

}