/*
 * PEnetration TEsting Proxy (PETEP)
 *
 * Copyright (C) 2021 Michal Válka
 *
 * This program is free software: you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program. If
 * not, see <https://www.gnu.org/licenses/>.
 */
package com.warxim.petep.extension.internal.history.repository;

import java.util.HashMap;
import java.util.Map;
import java.util.function.Function;

/**
 * Entity cache for caching queries.
 * <p>Entity cache is currently backed by {@link HashMap}.</p>
 * @param <K> Type of cached key
 * @param <V> Type of cached value
 */
public class EntityCache<K, V> {
    private Map<K, V> entities;

    /**
     * Constructs entity cache.
     */
    public EntityCache() {
        entities = new HashMap<>();
    }

    /**
     * Obtains value for given key or generates it using specified provided and returns generated value.
     * @param key Key for searching the entity
     * @param provider Provider for generating the entity if it does not exist already
     * @return Value for given key
     */
    public V computeIfAbsent(K key, Function<K, V> provider) {
        return entities.computeIfAbsent(key, provider);
    }

    /**
     * Clears the whole cache of entities.
     */
    public void clear() {
        entities.clear();
    }
}
