/*
 * Copyright 2016-2018 shardingsphere.io.
 * <p>
 * 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.
 * </p>
 */

package io.shardingsphere.transaction.xa.convert.swap;

import com.google.common.base.Optional;
import lombok.Getter;
import lombok.RequiredArgsConstructor;

import java.util.Map;

/**
 * Advanced map updater.
 *
 * @author zhaojun
 */
@RequiredArgsConstructor
final class AdvancedMapUpdater<K, V> {
    
    @Getter
    private final Map<K, V> delegateMap;
    
    /**
     * Update delegate map if value is present.
     * @param from old key
     * @param to new key
     */
    void transfer(final K from, final K to) {
        Optional<V> originValue = get(from);
        if (originValue.isPresent()) {
            delegateMap.put(to, originValue.get());
        }
    }
    
    /**
     * Get value by key.
     *
     * @param key key
     * @return optional value
     */
    private Optional<V> get(final K key) {
        return Optional.fromNullable(delegateMap.get(key));
    }
}
