/*
    *  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 static org.apache.commons.compress.archivers.zip.ZipArchiveEntryRequest.createZipArchiveEntryRequest;
  
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.util.Deque;
  import java.util.concurrent.Callable;
  import java.util.concurrent.ConcurrentLinkedDeque;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.Future;
  import java.util.concurrent.TimeUnit;
  import java.util.zip.Deflater;
  
  import org.apache.commons.compress.parallel.InputStreamSupplier;
  import org.apache.commons.compress.parallel.ScatterGatherBackingStore;
  import org.apache.commons.compress.parallel.ScatterGatherBackingStoreSupplier;
  
  /**
   * Creates a ZIP in parallel by using multiple threadlocal {@link ScatterZipOutputStream} instances.
   * <p>
   * Note that until 1.18, this class generally made no guarantees about the order of things written to the output file. Things that needed to come in a specific
   * order (manifests, directories) had to be handled by the client of this class, usually by writing these things to the {@link ZipArchiveOutputStream}
   * <em>before</em> calling {@link #writeTo writeTo} on this class.
   * </p>
   * <p>
   * The client can supply an {@link java.util.concurrent.ExecutorService}, but for reasons of memory model consistency, this will be shut down by this class
   * prior to completion.
   * </p>
   *
   * @since 1.10
   */
  public class ParallelScatterZipCreator {
  
      private final Deque<ScatterZipOutputStream> streams = new ConcurrentLinkedDeque<>();
      private final ExecutorService executorService;
      private final ScatterGatherBackingStoreSupplier backingStoreSupplier;
  
      private final Deque<Future<? extends ScatterZipOutputStream>> futures = new ConcurrentLinkedDeque<>();
      private final long startedAt = System.currentTimeMillis();
      private long compressionDoneAt;
      private long scatterDoneAt;
  
      private final int compressionLevel;
  
      private final ThreadLocal<ScatterZipOutputStream> tlScatterStreams = new ThreadLocal<ScatterZipOutputStream>() {
          @Override
          protected ScatterZipOutputStream initialValue() {
              try {
                  final ScatterZipOutputStream scatterStream = createDeferred(backingStoreSupplier);
                  streams.add(scatterStream);
                  return scatterStream;
              } catch (final IOException e) {
                  throw new UncheckedIOException(e); // NOSONAR
              }
          }
      };
  
      /**
       * Constructs a ParallelScatterZipCreator with default threads, which is set to the number of available processors, as defined by
       * {@link Runtime#availableProcessors}
       */
      public ParallelScatterZipCreator() {
          this(Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors()));
      }
  
      /**
       * Constructs a ParallelScatterZipCreator
       *
       * @param executorService The executorService to use for parallel scheduling. For technical reasons, this will be shut down by this class.
       */
      public ParallelScatterZipCreator(final ExecutorService executorService) {
          this(executorService, new DefaultBackingStoreSupplier(null));
      }
  
      /**
       * Constructs a ParallelScatterZipCreator
       *
       * @param executorService      The executorService to use. For technical reasons, this will be shut down by this class.
       * @param backingStoreSupplier The supplier of backing store which shall be used
       */
     public ParallelScatterZipCreator(final ExecutorService executorService, final ScatterGatherBackingStoreSupplier backingStoreSupplier) {
         this(executorService, backingStoreSupplier, Deflater.DEFAULT_COMPRESSION);
     }
 
     /**
      * Constructs a ParallelScatterZipCreator
      *
      * @param executorService      The executorService to use. For technical reasons, this will be shut down by this class.
      * @param backingStoreSupplier The supplier of backing store which shall be used
      * @param compressionLevel     The compression level used in compression, this value should be -1(default level) or between 0~9.
      * @throws IllegalArgumentException if the compression level is illegal
      * @since 1.21
      */
     public ParallelScatterZipCreator(final ExecutorService executorService, final ScatterGatherBackingStoreSupplier backingStoreSupplier,
             final int compressionLevel) throws IllegalArgumentException {
         if ((compressionLevel < Deflater.NO_COMPRESSION || compressionLevel > Deflater.BEST_COMPRESSION) && compressionLevel != Deflater.DEFAULT_COMPRESSION) {
             throw new IllegalArgumentException("Compression level is expected between -1~9");
         }
 
         this.backingStoreSupplier = backingStoreSupplier;
         this.executorService = executorService;
         this.compressionLevel = compressionLevel;
     }
 
     /**
      * Adds an archive entry to this archive.
      * <p>
      * This method is expected to be called from a single client thread
      * </p>
      *
      * @param zipArchiveEntry The entry to add.
      * @param source          The source input stream supplier
      */
 
     public void addArchiveEntry(final ZipArchiveEntry zipArchiveEntry, final InputStreamSupplier source) {
         submitStreamAwareCallable(createCallable(zipArchiveEntry, source));
     }
 
     /**
      * Adds an archive entry to this archive.
      * <p>
      * This method is expected to be called from a single client thread
      * </p>
      *
      * @param zipArchiveEntryRequestSupplier Should supply the entry to be added.
      * @since 1.13
      */
     public void addArchiveEntry(final ZipArchiveEntryRequestSupplier zipArchiveEntryRequestSupplier) {
         submitStreamAwareCallable(createCallable(zipArchiveEntryRequestSupplier));
     }
 
     private void closeAll() {
         for (final ScatterZipOutputStream scatterStream : streams) {
             try {
                 scatterStream.close();
             } catch (final IOException ignored) {
                 // no way to properly log this
             }
         }
     }
 
     /**
      * Creates a callable that will compress the given archive entry.
      *
      * <p>
      * This method is expected to be called from a single client thread.
      * </p>
      *
      * Consider using {@link #addArchiveEntry addArchiveEntry}, which wraps this method and {@link #submitStreamAwareCallable submitStreamAwareCallable}. The
      * most common use case for using {@link #createCallable createCallable} and {@link #submitStreamAwareCallable submitStreamAwareCallable} from a client is
      * if you want to wrap the callable in something that can be prioritized by the supplied {@link ExecutorService}, for instance to process large or slow
      * files first. Since the creation of the {@link ExecutorService} is handled by the client, all of this is up to the client.
      *
      * @param zipArchiveEntry The entry to add.
      * @param source          The source input stream supplier
      * @return A callable that should subsequently be passed to #submitStreamAwareCallable, possibly in a wrapped/adapted from. The value of this callable is
      *         not used, but any exceptions happening inside the compression will be propagated through the callable.
      */
 
     public final Callable<ScatterZipOutputStream> createCallable(final ZipArchiveEntry zipArchiveEntry, final InputStreamSupplier source) {
         final int method = zipArchiveEntry.getMethod();
         if (method == ZipMethod.UNKNOWN_CODE) {
             throw new IllegalArgumentException("Method must be set on zipArchiveEntry: " + zipArchiveEntry);
         }
         final ZipArchiveEntryRequest zipArchiveEntryRequest = createZipArchiveEntryRequest(zipArchiveEntry, source);
         return () -> {
             final ScatterZipOutputStream scatterStream = tlScatterStreams.get();
             scatterStream.addArchiveEntry(zipArchiveEntryRequest);
             return scatterStream;
         };
     }
 
     /**
      * Creates a callable that will compress archive entry supplied by {@link ZipArchiveEntryRequestSupplier}.
      *
      * <p>
      * This method is expected to be called from a single client thread.
      * </p>
      *
      * The same as {@link #createCallable(ZipArchiveEntry, InputStreamSupplier)}, but the archive entry to be added is supplied by a
      * {@link ZipArchiveEntryRequestSupplier}.
      *
      * @see #createCallable(ZipArchiveEntry, InputStreamSupplier)
      *
      * @param zipArchiveEntryRequestSupplier Should supply the entry to be added.
      * @return A callable that should subsequently be passed to #submitStreamAwareCallable, possibly in a wrapped/adapted from. The value of this callable is
      *         not used, but any exceptions happening inside the compression will be propagated through the callable.
      * @since 1.13
      */
     public final Callable<ScatterZipOutputStream> createCallable(final ZipArchiveEntryRequestSupplier zipArchiveEntryRequestSupplier) {
         return () -> {
             final ScatterZipOutputStream scatterStream = tlScatterStreams.get();
             scatterStream.addArchiveEntry(zipArchiveEntryRequestSupplier.get());
             return scatterStream;
         };
     }
 
     @SuppressWarnings("resource") // Caller closes
     private ScatterZipOutputStream createDeferred(final ScatterGatherBackingStoreSupplier scatterGatherBackingStoreSupplier) throws IOException {
         final ScatterGatherBackingStore bs = scatterGatherBackingStoreSupplier.get();
         // lifecycle is bound to the ScatterZipOutputStream returned
         final StreamCompressor sc = StreamCompressor.create(compressionLevel, bs); // NOSONAR
         return new ScatterZipOutputStream(bs, sc);
     }
 
     /**
      * Gets a message describing the overall statistics of the compression run
      *
      * @return A string
      */
     public ScatterStatistics getStatisticsMessage() {
         return new ScatterStatistics(compressionDoneAt - startedAt, scatterDoneAt - compressionDoneAt);
     }
 
     /**
      * Submits a callable for compression.
      *
      * @see ParallelScatterZipCreator#createCallable for details of if/when to use this.
      *
      * @param callable The callable to run, created by {@link #createCallable createCallable}, possibly wrapped by caller.
      */
     public final void submit(final Callable<? extends Object> callable) {
         submitStreamAwareCallable(() -> {
             callable.call();
             return tlScatterStreams.get();
         });
     }
 
     /**
      * Submits a callable for compression.
      *
      * @see ParallelScatterZipCreator#createCallable for details of if/when to use this.
      *
      * @param callable The callable to run, created by {@link #createCallable createCallable}, possibly wrapped by caller.
      * @since 1.19
      */
     public final void submitStreamAwareCallable(final Callable<? extends ScatterZipOutputStream> callable) {
         futures.add(executorService.submit(callable));
     }
 
     /**
      * Writes the contents this to the target {@link ZipArchiveOutputStream}.
      * <p>
      * It may be beneficial to write things like directories and manifest files to the targetStream before calling this method.
      * </p>
      * <p>
      * Calling this method will shut down the {@link ExecutorService} used by this class. If any of the {@link Callable}s {@link #submitStreamAwareCallable
      * submit}ted to this instance throws an exception, the archive can not be created properly and this method will throw an exception.
      * </p>
      *
      * @param targetStream The {@link ZipArchiveOutputStream} to receive the contents of the scatter streams
      * @throws IOException          If writing fails
      * @throws InterruptedException If we get interrupted
      * @throws ExecutionException   If something happens in the parallel execution
      */
     public void writeTo(final ZipArchiveOutputStream targetStream) throws IOException, InterruptedException, ExecutionException {
 
         try {
             // Make sure we catch any exceptions from parallel phase
             try {
                 for (final Future<?> future : futures) {
                     future.get();
                 }
             } finally {
                 executorService.shutdown();
             }
 
             executorService.awaitTermination(1000 * 60L, TimeUnit.SECONDS); // == Infinity. We really *must* wait for this to complete
 
             // It is important that all threads terminate before we go on, ensure happens-before relationship
             compressionDoneAt = System.currentTimeMillis();
 
             for (final Future<? extends ScatterZipOutputStream> future : futures) {
                 final ScatterZipOutputStream scatterStream = future.get();
                 scatterStream.zipEntryWriter().writeNextZipEntry(targetStream);
             }
 
             for (final ScatterZipOutputStream scatterStream : streams) {
                 scatterStream.close();
             }
 
             scatterDoneAt = System.currentTimeMillis();
         } finally {
             closeAll();
         }
     }
 }