/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *
 *   https://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.apache.commons.compress.archivers.zip;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.commons.compress.parallel.FileBasedScatterGatherBackingStore;
import org.apache.commons.compress.parallel.ScatterGatherBackingStore;
import org.apache.commons.compress.parallel.ScatterGatherBackingStoreSupplier;

/**
 * Implements {@link ScatterGatherBackingStoreSupplier} using a temporary folder.
 * <p>
 * For example:
 * </p>
 *
 * <pre>
 * final Path dir = Paths.get("target/custom-temp-dir");
 * Files.createDirectories(dir);
 * final ParallelScatterZipCreator zipCreator = new ParallelScatterZipCreator(Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors()),
 *         new DefaultBackingStoreSupplier(dir));
 * </pre>
 *
 * @since 1.23
 */
public class DefaultBackingStoreSupplier implements ScatterGatherBackingStoreSupplier {

    private static final String PREFIX = "parallelscatter";

    private final AtomicInteger storeNum = new AtomicInteger();

    private final Path dir;

    /**
     * Constructs a new instance. If {@code dir} is null, then use the default temporary-file directory.
     *
     * @param dir temporary folder, may be null, must exist if non-null.
     */
    public DefaultBackingStoreSupplier(final Path dir) {
        this.dir = dir;
    }

    @Override
    public ScatterGatherBackingStore get() throws IOException {
        final String suffix = "n" + storeNum.incrementAndGet();
        final Path tempFile = dir == null ? Files.createTempFile(PREFIX, suffix) : Files.createTempFile(dir, PREFIX, suffix);
        return new FileBasedScatterGatherBackingStore(tempFile);
    }
}
