/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collection;
import java.util.Comparator;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import org.checkerframework.checker.nullness.qual.Nullable;

Implementation of Multimap whose keys and values are ordered by their natural ordering or by supplied comparators. In all cases, this implementation uses Comparable.compareTo or Comparator.compare instead of Object.equals to determine equivalence of instances. 
Warning: The comparators or comparables used must be consistent with equals as explained by the Comparable class specification. Otherwise, the resulting multiset will violate the general contract of SetMultimap, which it is specified in terms of Object.equals. 
The collections returned by keySet and asMap iterate through the keys according to the key comparator ordering or the natural ordering of the keys. Similarly, 
get, removeAll, and replaceValues return collections that iterate through the values according to the value comparator ordering or the natural ordering of the values. The collections generated by entries, keys, and values iterate across the keys according to the above key ordering, and for each key they iterate across the values according to the value ordering. 
The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
existing key-value pair has no effect.
Null keys and values are permitted (provided, of course, that the respective comparators
support them). All optional multimap methods are supported, and all returned views are
modifiable.
This class is not threadsafe when any concurrent operations update the multimap. Concurrent read operations will work correctly. To allow concurrent update operations, wrap your multimap with a call to Multimaps.synchronizedSortedSetMultimap. 
See the Guava User Guide article on  
Multimap.
Author:
Jared Levy, Louis Wasserman
Since:
2.0/**
 * Implementation of {@code Multimap} whose keys and values are ordered by their natural ordering or
 * by supplied comparators. In all cases, this implementation uses {@link Comparable#compareTo} or
 * {@link Comparator#compare} instead of {@link Object#equals} to determine equivalence of
 * instances.
 *
 * <p><b>Warning:</b> The comparators or comparables used must be <i>consistent with equals</i> as
 * explained by the {@link Comparable} class specification. Otherwise, the resulting multiset will
 * violate the general contract of {@link SetMultimap}, which it is specified in terms of {@link
 * Object#equals}.
 *
 * <p>The collections returned by {@code keySet} and {@code asMap} iterate through the keys
 * according to the key comparator ordering or the natural ordering of the keys. Similarly, {@code
 * get}, {@code removeAll}, and {@code replaceValues} return collections that iterate through the
 * values according to the value comparator ordering or the natural ordering of the values. The
 * collections generated by {@code entries}, {@code keys}, and {@code values} iterate across the
 * keys according to the above key ordering, and for each key they iterate across the values
 * according to the value ordering.
 *
 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
 * existing key-value pair has no effect.
 *
 * <p>Null keys and values are permitted (provided, of course, that the respective comparators
 * support them). All optional multimap methods are supported, and all returned views are
 * modifiable.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
 * read operations will work correctly. To allow concurrent update operations, wrap your multimap
 * with a call to {@link Multimaps#synchronizedSortedSetMultimap}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
 * Multimap}</a>.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible(serializable = true, emulated = true)
public class TreeMultimap<K, V> extends AbstractSortedKeySortedSetMultimap<K, V> {
  private transient Comparator<? super K> keyComparator;
  private transient Comparator<? super V> valueComparator;

  
Creates an empty TreeMultimap ordered by the natural ordering of its keys and values. /**
   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
   */
  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
    return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
  }

  
Creates an empty TreeMultimap instance using explicit comparators. Neither comparator may be null; use Ordering.natural() to specify natural order. 
Params:
keyComparator – the comparator that determines the key ordering
valueComparator – the comparator that determines the value ordering/**
   * Creates an empty {@code TreeMultimap} instance using explicit comparators. Neither comparator
   * may be null; use {@link Ordering#natural()} to specify natural order.
   *
   * @param keyComparator the comparator that determines the key ordering
   * @param valueComparator the comparator that determines the value ordering
   */
  public static <K, V> TreeMultimap<K, V> create(
      Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
    return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
  }

  
Constructs a TreeMultimap, ordered by the natural ordering of its keys and values, with the same mappings as the specified multimap. 
Params:
multimap – the multimap whose contents are copied to this multimap/**
   * Constructs a {@code TreeMultimap}, ordered by the natural ordering of its keys and values, with
   * the same mappings as the specified multimap.
   *
   * @param multimap the multimap whose contents are copied to this multimap
   */
  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create(
      Multimap<? extends K, ? extends V> multimap) {
    return new TreeMultimap<>(Ordering.natural(), Ordering.natural(), multimap);
  }

  TreeMultimap(Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
    super(new TreeMap<K, Collection<V>>(keyComparator));
    this.keyComparator = keyComparator;
    this.valueComparator = valueComparator;
  }

  private TreeMultimap(
      Comparator<? super K> keyComparator,
      Comparator<? super V> valueComparator,
      Multimap<? extends K, ? extends V> multimap) {
    this(keyComparator, valueComparator);
    putAll(multimap);
  }

  @Override
  Map<K, Collection<V>> createAsMap() {
    return createMaybeNavigableAsMap();
  }

  
{@inheritDoc}
Creates an empty TreeSet for a collection of values for one key. 
Returns:
a new TreeSet containing a collection of values for one key/**
   * {@inheritDoc}
   *
   * <p>Creates an empty {@code TreeSet} for a collection of values for one key.
   *
   * @return a new {@code TreeSet} containing a collection of values for one key
   */
  @Override
  SortedSet<V> createCollection() {
    return new TreeSet<V>(valueComparator);
  }

  @Override
  Collection<V> createCollection(@Nullable K key) {
    if (key == null) {
      keyComparator().compare(key, key);
    }
    return super.createCollection(key);
  }

  
Returns the comparator that orders the multimap keys.
Deprecated:
Use ((NavigableSet<K>) multimap.keySet()).comparator() instead./**
   * Returns the comparator that orders the multimap keys.
   *
   * @deprecated Use {@code ((NavigableSet<K>) multimap.keySet()).comparator()} instead.
   */
  @Deprecated
  public Comparator<? super K> keyComparator() {
    return keyComparator;
  }

  @Override
  public Comparator<? super V> valueComparator() {
    return valueComparator;
  }

  
Since:
14.0 (present with return type SortedSet since 2.0)/** @since 14.0 (present with return type {@code SortedSet} since 2.0) */
  @Override
  @GwtIncompatible // NavigableSet
  public NavigableSet<V> get(@Nullable K key) {
    return (NavigableSet<V>) super.get(key);
  }

  
{@inheritDoc}
Because a TreeMultimap has unique sorted keys, this method returns a NavigableSet, instead of the Set specified in the Multimap interface. 
Since:
14.0 (present with return type SortedSet since 2.0)/**
   * {@inheritDoc}
   *
   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
   * NavigableSet}, instead of the {@link java.util.Set} specified in the {@link Multimap}
   * interface.
   *
   * @since 14.0 (present with return type {@code SortedSet} since 2.0)
   */
  @Override
  public NavigableSet<K> keySet() {
    return (NavigableSet<K>) super.keySet();
  }

  
{@inheritDoc}
Because a TreeMultimap has unique sorted keys, this method returns a NavigableMap, instead of the Map specified in the Multimap interface. 
Since:
14.0 (present with return type SortedMap since 2.0)/**
   * {@inheritDoc}
   *
   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
   * NavigableMap}, instead of the {@link java.util.Map} specified in the {@link Multimap}
   * interface.
   *
   * @since 14.0 (present with return type {@code SortedMap} since 2.0)
   */
  @Override
  public NavigableMap<K, Collection<V>> asMap() {
    return (NavigableMap<K, Collection<V>>) super.asMap();
  }

  
@serialData
key comparator, value comparator, number of distinct keys, and then for each
    distinct key: the key, number of values for that key, and key values/**
   * @serialData key comparator, value comparator, number of distinct keys, and then for each
   *     distinct key: the key, number of values for that key, and key values
   */
  @GwtIncompatible // java.io.ObjectOutputStream
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(keyComparator());
    stream.writeObject(valueComparator());
    Serialization.writeMultimap(this, stream);
  }

  @GwtIncompatible // java.io.ObjectInputStream
  @SuppressWarnings("unchecked") // reading data stored by writeObject
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
    keyComparator = checkNotNull((Comparator<? super K>) stream.readObject());
    valueComparator = checkNotNull((Comparator<? super V>) stream.readObject());
    setMap(new TreeMap<K, Collection<V>>(keyComparator));
    Serialization.populateMultimap(this, stream);
  }

  @GwtIncompatible // not needed in emulated source
  private static final long serialVersionUID = 0;
}