/*
 * 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 java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Map;
import java.util.SortedSet;

import javax.annotation.Nullable;

import com.google.common.annotations.GwtCompatible;

/**
 * Basic implementation of the {@link SortedSetMultimap} interface. It's a
 * wrapper around {@link AbstractMapBasedMultimap} that converts the returned
 * collections into sorted sets. The {@link #createCollection} method must
 * return a {@code SortedSet}.
 *
 * @author Jared Levy
 */
@GwtCompatible
abstract class AbstractSortedSetMultimap<K, V> extends AbstractSetMultimap<K, V> implements SortedSetMultimap<K, V> {
	/**
	 * Creates a new multimap that uses the provided map.
	 *
	 * @param map place to store the mapping from each key to its corresponding
	 *            values
	 */
	protected AbstractSortedSetMultimap(Map<K, Collection<V>> map) {
		super(map);
	}

	@Override
	abstract SortedSet<V> createCollection();

	@Override
	SortedSet<V> createUnmodifiableEmptyCollection() {
		Comparator<? super V> comparator = valueComparator();
		if (comparator == null) {
			return Collections.unmodifiableSortedSet(createCollection());
		} else {
			return ImmutableSortedSet.emptySet(valueComparator());
		}
	}

	// Following Javadoc copied from Multimap and SortedSetMultimap.

	/**
	 * Returns a collection view of all values associated with a key. If no mappings
	 * in the multimap have the provided key, an empty collection is returned.
	 *
	 * <p>
	 * Changes to the returned collection will update the underlying multimap, and
	 * vice versa.
	 *
	 * <p>
	 * Because a {@code SortedSetMultimap} has unique sorted values for a given key,
	 * this method returns a {@link SortedSet}, instead of the {@link Collection}
	 * specified in the {@link Multimap} interface.
	 */
	@Override
	public SortedSet<V> get(@Nullable K key) {
		return (SortedSet<V>) super.get(key);
	}

	/**
	 * Removes all values associated with a given key. The returned collection is
	 * immutable.
	 *
	 * <p>
	 * Because a {@code SortedSetMultimap} has unique sorted values for a given key,
	 * this method returns a {@link SortedSet}, instead of the {@link Collection}
	 * specified in the {@link Multimap} interface.
	 */
	@Override
	public SortedSet<V> removeAll(@Nullable Object key) {
		return (SortedSet<V>) super.removeAll(key);
	}

	/**
	 * Stores a collection of values with the same key, replacing any existing
	 * values for that key. The returned collection is immutable.
	 *
	 * <p>
	 * Because a {@code SortedSetMultimap} has unique sorted values for a given key,
	 * this method returns a {@link SortedSet}, instead of the {@link Collection}
	 * specified in the {@link Multimap} interface.
	 *
	 * <p>
	 * Any duplicates in {@code values} will be stored in the multimap once.
	 */
	@Override
	public SortedSet<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
		return (SortedSet<V>) super.replaceValues(key, values);
	}

	/**
	 * Returns a map view that associates each key with the corresponding values in
	 * the multimap. Changes to the returned map, such as element removal, will
	 * update the underlying multimap. The map does not support {@code setValue} on
	 * its entries, {@code put}, or {@code putAll}.
	 *
	 * <p>
	 * When passed a key that is present in the map, {@code
	 * asMap().get(Object)} has the same behavior as {@link #get}, returning a live
	 * collection. When passed a key that is not present, however, {@code
	 * asMap().get(Object)} returns {@code null} instead of an empty collection.
	 *
	 * <p>
	 * Though the method signature doesn't say so explicitly, the returned map has
	 * {@link SortedSet} values.
	 */
	@Override
	public Map<K, Collection<V>> asMap() {
		return super.asMap();
	}

	/**
	 * {@inheritDoc}
	 *
	 * Consequently, the values do not follow their natural ordering or the ordering
	 * of the value comparator.
	 */
	@Override
	public Collection<V> values() {
		return super.values();
	}

	private static final long serialVersionUID = 430848587173315748L;
}
