/*

 * 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.commons.collections4.multimap;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.Serializable;

import java.util.ArrayList;

import java.util.Collection;

import java.util.HashMap;

import java.util.Map;

import org.apache.commons.collections4.MultiValuedMap;

/**

 * Implements a {@code ListValuedMap}, using a {@link HashMap} to provide data

 * storage and {@link ArrayList}s as value collections. This is the standard

 * implementation of a ListValuedMap.

 * <p>

 * <strong>Note that ArrayListValuedHashMap is not synchronized and is not

 * thread-safe.</strong> If you wish to use this map from multiple threads

 * concurrently, you must use appropriate synchronization. This class may throw

 * exceptions when accessed by concurrent threads without synchronization.

 * </p>

 *

 * @param <K> the type of the keys in this map

 * @param <V> the type of the values in this map

 * @since 4.1

 */

public class ArrayListValuedHashMap<K, V> extends AbstractListValuedMap<K, V>

    implements Serializable {

    /** Serialization Version */

    private static final long serialVersionUID = 20151118L;

    /**

     * The initial map capacity used when none specified in constructor.

     */

    private static final int DEFAULT_INITIAL_MAP_CAPACITY = 16;

    /**

     * The initial list capacity when using none specified in constructor.

     */

    private static final int DEFAULT_INITIAL_LIST_CAPACITY = 3;

    /**

     * The initial list capacity when creating a new value collection.

     */

    private final int initialListCapacity;

    /**

     * Creates an empty ArrayListValuedHashMap with the default initial

     * map capacity (16) and the default initial list capacity (3).

     */

    public ArrayListValuedHashMap() {

        this(DEFAULT_INITIAL_MAP_CAPACITY, DEFAULT_INITIAL_LIST_CAPACITY);

    }

    /**

     * Creates an empty ArrayListValuedHashMap with the default initial

     * map capacity (16) and the specified initial list capacity.

     *

     * @param initialListCapacity  the initial capacity used for value collections

     */

    public ArrayListValuedHashMap(final int initialListCapacity) {

        this(DEFAULT_INITIAL_MAP_CAPACITY, initialListCapacity);

    }

    /**

     * Creates an empty ArrayListValuedHashMap with the specified initial

     * map and list capacities.

     *

     * @param initialMapCapacity  the initial hashmap capacity

     * @param initialListCapacity  the initial capacity used for value collections

     */

    public ArrayListValuedHashMap(final int initialMapCapacity, final int initialListCapacity) {

        super(new HashMap<K, ArrayList<V>>(initialMapCapacity));

        this.initialListCapacity = initialListCapacity;

    }

    /**

     * Creates an ArrayListValuedHashMap copying all the mappings of the given map.

     *

     * @param map a <code>MultiValuedMap</code> to copy into this map

     */

    public ArrayListValuedHashMap(final MultiValuedMap<? extends K, ? extends V> map) {

        this(map.size(), DEFAULT_INITIAL_LIST_CAPACITY);

        super.putAll(map);

    }

    /**

     * Creates an ArrayListValuedHashMap copying all the mappings of the given map.

     *

     * @param map a <code>Map</code> to copy into this map

     */

    public ArrayListValuedHashMap(final Map<? extends K, ? extends V> map) {

        this(map.size(), DEFAULT_INITIAL_LIST_CAPACITY);

        super.putAll(map);

    }

    // -----------------------------------------------------------------------

    @Override

    protected ArrayList<V> createCollection() {

        return new ArrayList<>(initialListCapacity);

    }

    // -----------------------------------------------------------------------

    /**

     * Trims the capacity of all value collections to their current size.

     */

    public void trimToSize() {

        for (final Collection<V> coll : getMap().values()) {

            final ArrayList<V> list = (ArrayList<V>) coll;

            list.trimToSize();

        }

    }

    // -----------------------------------------------------------------------

    private void writeObject(final ObjectOutputStream oos) throws IOException {

        oos.defaultWriteObject();

        doWriteObject(oos);

    }

    private void readObject(final ObjectInputStream ois) throws IOException, ClassNotFoundException {

        ois.defaultReadObject();

        setMap(new HashMap<K, ArrayList<V>>());

        doReadObject(ois);

    }

}