/*
 * Copyright 2016 Open Networking Laboratory
 *
 * 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 org.onosproject.store.primitives.impl;

import java.util.function.Function;

import org.onosproject.store.service.AsyncConsistentMap;
import org.onosproject.store.service.AsyncDistributedSet;

/**
 * Misc utilities for working with {@code DistributedPrimitive}s.
 */
public final class DistributedPrimitives {

    private DistributedPrimitives() {}

    /**
     * Creates an instance of {@code AsyncDistributedSet} that is backed by a {@code AsyncConsistentMap}.
     *
     * @param map backing map
     * @return set
     * @param <E> set element type
     */
    public static <E> AsyncDistributedSet<E> newSetFromMap(AsyncConsistentMap<E, Boolean> map) {
        return new DefaultAsyncDistributedSet<>(map, map.name(), true);
    }

    /**
     * Creates an instance of {@code AsyncConsistentMap} that records metrics for all its operations.
     *
     * @param map map whose operations are to be metered
     * @return metered map
     * @param <K> map key type
     * @param <V> map value type
     */
    public static <K, V> AsyncConsistentMap<K, V> newMeteredMap(AsyncConsistentMap<K, V> map) {
        return new MeteredAsyncConsistentMap<>(map);
    }

    /**
     * Creates an instance of {@code AsyncConsistentMap} that caches entries on get.
     *
     * @param map backing map
     * @return caching map
     * @param <K> map key type
     * @param <V> map value type
     */
    public static <K, V> AsyncConsistentMap<K, V> newCachingMap(AsyncConsistentMap<K, V> map) {
        return new CachingAsyncConsistentMap<>(map);
    }

    /**
     * Creates an instance of {@code AsyncConsistentMap} that disallows updates.
     *
     * @param map backing map
     * @return unmodifiable map
     * @param <K> map key type
     * @param <V> map value type
     */
    public static <K, V> AsyncConsistentMap<K, V> newUnmodifiableMap(AsyncConsistentMap<K, V> map) {
        return new UnmodifiableAsyncConsistentMap<>(map);
    }

    /**
     * Creates an instance of {@code AsyncConsistentMap} that transforms operations inputs and applies them
     * to corresponding operation in a different typed map and returns the output after reverse transforming it.
     *
     * @param map backing map
     * @param keyEncoder transformer for key type of returned map to key type of input map
     * @param keyDecoder transformer for key type of input map to key type of returned map
     * @param valueEncoder transformer for value type of returned map to value type of input map
     * @param valueDecoder transformer for value type of input map to value type of returned map
     * @param <K1> returned map key type
     * @param <K2> input map key type
     * @param <V1> returned map value type
     * @param <V2> input map key type
     * @return new map
     */
    public static <K1, V1, K2, V2> AsyncConsistentMap<K1, V1> newTranscodingMap(AsyncConsistentMap<K2, V2> map,
            Function<K1, K2> keyEncoder,
            Function<K2, K1> keyDecoder,
            Function<V1, V2> valueEncoder,
            Function<V2, V1> valueDecoder) {
        return new TranscodingAsyncConsistentMap<K1, V1, K2, V2>(map,
                keyEncoder,
                keyDecoder,
                valueEncoder,
                valueDecoder);
    }
}