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/*
 * Copyright 2017 ~ 2025 the original author or authors. James Wong 
 *
 * 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.wl4g.infra.common.collection.multimap;

import java.util.List;
import java.util.Map;

/**
 * Extension of the {@code Map} interface that stores multiple values.
 *
 * @param 
 *            the key type
 * @param 
 *            the value element type
 */
public interface MultiValueMap extends Map> {

    /**
     * Return the first value for the given key.
     * 
     * @param key
     *            the key
     * @return the first value for the specified key, or {@code null} if none
     */
    V getFirst(K key);

    /**
     * Add the given single value to the current list of values for the given
     * key.
     * 
     * @param key
     *            the key
     * @param value
     *            the value to be added
     */
    void add(K key, V value);

    /**
     * Add all the values of the given list to the current list of values for
     * the given key.
     * 
     * @param key
     *            they key
     * @param values
     *            the values to be added
     * @since 5.0
     */
    void addAll(K key, List values);

    /**
     * Add all the values of the given {@code MultiValueMap} to the current
     * values.
     * 
     * @param values
     *            the values to be added
     * @since 5.0
     */
    void addAll(MultiValueMap values);

    /**
     * {@link #add(Object, Object) Add} the given value, only when the map does
     * not {@link #containsKey(Object) contain} the given key.
     * 
     * @param key
     *            the key
     * @param value
     *            the value to be added
     * @since 5.2
     */
    default void addIfAbsent(K key, V value) {
        if (!containsKey(key)) {
            add(key, value);
        }
    }

    /**
     * Set the given single value under the given key.
     * 
     * @param key
     *            the key
     * @param value
     *            the value to set
     */
    void set(K key, V value);

    /**
     * Set the given values under.
     * 
     * @param values
     *            the values.
     */
    void setAll(Map values);

    /**
     * Return a {@code Map} with the first values contained in this
     * {@code MultiValueMap}.
     * 
     * @return a single value representation of this map
     */
    Map toSingleValueMap();

}