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Apache Commons Compress defines an API for working with compression and archive formats. These include bzip2, gzip, pack200, LZMA, XZ, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4, Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.
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/*
 *  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
 *
 *      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.apache.commons.compress.archivers.zip;


import org.apache.commons.compress.parallel.FileBasedScatterGatherBackingStore;
import org.apache.commons.compress.parallel.ScatterGatherBackingStore;
import org.apache.commons.compress.utils.BoundedInputStream;

import java.io.Closeable;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.zip.Deflater;

/**
 * A zip output stream that is optimized for multi-threaded scatter/gather construction of zip files.
 * 
 * The internal data format of the entries used by this class are entirely private to this class
 * and are not part of any public api whatsoever.
 * 
 * It is possible to extend this class to support different kinds of backing storage, the default
 * implementation only supports file-based backing.
 * 
 * Thread safety: This class supports multiple threads. But the "writeTo" method must be called
 * by the thread that originally created the {@link ZipArchiveEntry}.
 *
 * @since 1.10
 */
public class ScatterZipOutputStream implements Closeable {
    private final Queue items = new ConcurrentLinkedQueue<>();
    private final ScatterGatherBackingStore backingStore;
    private final StreamCompressor streamCompressor;

    private static class CompressedEntry {
        final ZipArchiveEntryRequest zipArchiveEntryRequest;
        final long crc;
        final long compressedSize;
        final long size;

        public CompressedEntry(final ZipArchiveEntryRequest zipArchiveEntryRequest, final long crc, final long compressedSize, final long size) {
            this.zipArchiveEntryRequest = zipArchiveEntryRequest;
            this.crc = crc;
            this.compressedSize = compressedSize;
            this.size = size;
        }

        /**
         * Update the original {@link ZipArchiveEntry} with sizes/crc
         * Do not use this methods from threads that did not create the instance itself !
         * @return the zipArchiveEntry that is basis for this request
         */

        public ZipArchiveEntry transferToArchiveEntry(){
            final ZipArchiveEntry entry = zipArchiveEntryRequest.getZipArchiveEntry();
            entry.setCompressedSize(compressedSize);
            entry.setSize(size);
            entry.setCrc(crc);
            entry.setMethod(zipArchiveEntryRequest.getMethod());
            return entry;
        }
    }

    public ScatterZipOutputStream(final ScatterGatherBackingStore backingStore,
                                  final StreamCompressor streamCompressor) {
        this.backingStore = backingStore;
        this.streamCompressor = streamCompressor;
    }

    /**
     * Add an archive entry to this scatter stream.
     *
     * @param zipArchiveEntryRequest The entry to write.
     * @throws IOException    If writing fails
     */
    public void addArchiveEntry(final ZipArchiveEntryRequest zipArchiveEntryRequest) throws IOException {
        try (final InputStream payloadStream = zipArchiveEntryRequest.getPayloadStream()) {
            streamCompressor.deflate(payloadStream, zipArchiveEntryRequest.getMethod());
        }
        items.add(new CompressedEntry(zipArchiveEntryRequest, streamCompressor.getCrc32(),
                                      streamCompressor.getBytesWrittenForLastEntry(), streamCompressor.getBytesRead()));
    }

    /**
     * Write the contents of this scatter stream to a target archive.
     *
     * @param target The archive to receive the contents of this {@link ScatterZipOutputStream}.
     * @throws IOException If writing fails
     */
    public void writeTo(final ZipArchiveOutputStream target) throws IOException {
        backingStore.closeForWriting();
        try (final InputStream data = backingStore.getInputStream()) {
            for (final CompressedEntry compressedEntry : items) {
                try (final BoundedInputStream rawStream = new BoundedInputStream(data,
                        compressedEntry.compressedSize)) {
                    target.addRawArchiveEntry(compressedEntry.transferToArchiveEntry(), rawStream);
                }
            }
        }
    }


    /**
     * Closes this stream, freeing all resources involved in the creation of this stream.
     * @throws IOException If closing fails
     */
    @Override
    public void close() throws IOException {
        backingStore.close();
        streamCompressor.close();
    }

    /**
     * Create a {@link ScatterZipOutputStream} with default compression level that is backed by a file
     *
     * @param file The file to offload compressed data into.
     * @return A ScatterZipOutputStream that is ready for use.
     * @throws FileNotFoundException if the file cannot be found
     */
    public static ScatterZipOutputStream fileBased(final File file) throws FileNotFoundException {
        return fileBased(file, Deflater.DEFAULT_COMPRESSION);
    }

    /**
     * Create a {@link ScatterZipOutputStream} that is backed by a file
     *
     * @param file             The file to offload compressed data into.
     * @param compressionLevel The compression level to use, @see #Deflater
     * @return A  ScatterZipOutputStream that is ready for use.
     * @throws FileNotFoundException if the file cannot be found
     */
    public static ScatterZipOutputStream fileBased(final File file, final int compressionLevel) throws FileNotFoundException {
        final ScatterGatherBackingStore bs = new FileBasedScatterGatherBackingStore(file);
        // lifecycle is bound to the ScatterZipOutputStream returned
        final StreamCompressor sc = StreamCompressor.create(compressionLevel, bs); //NOSONAR
        return new ScatterZipOutputStream(bs, sc);
    }
}