/*
 * 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.lucene.util;

import java.util.Collection;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * Helper class for keeping Lists of Objects associated with keys. <b>WARNING: THIS CLASS IS NOT
 * THREAD SAFE</b>
 *
 * @lucene.internal
 */
public class MapOfSets<K, V> {

  private final Map<K, Set<V>> theMap;

  /**
   * @param m the backing store for this object
   */
  public MapOfSets(Map<K, Set<V>> m) {
    theMap = m;
  }

  /**
   * @return direct access to the map backing this object.
   */
  public Map<K, Set<V>> getMap() {
    return theMap;
  }

  /**
   * Adds val to the Set associated with key in the Map. If key is not already in the map, a new Set
   * will first be created.
   *
   * @return the size of the Set associated with key once val is added to it.
   */
  public int put(K key, V val) {
    final Set<V> theSet = theMap.computeIfAbsent(key, k -> new HashSet<>(23));
    theSet.add(val);
    return theSet.size();
  }

  /**
   * Adds multiple vals to the Set associated with key in the Map. If key is not already in the map,
   * a new Set will first be created.
   *
   * @return the size of the Set associated with key once val is added to it.
   */
  public int putAll(K key, Collection<? extends V> vals) {
    final Set<V> theSet = theMap.computeIfAbsent(key, k -> new HashSet<>(23));
    theSet.addAll(vals);
    return theSet.size();
  }
}
