EDIT

/**

* Copyright (C) 2017 EDIT

* European Distributed Institute of Taxonomy

* http://www.e-taxonomy.eu

*

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.cdm.io.common;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.util.HashMap;

import java.util.Map;

import java.util.zip.ZipEntry;

import java.util.zip.ZipOutputStream;

import org.apache.commons.io.output.DeferredFileOutputStream;

/**

 * Writing to zip files is not possible in parallel.

 * This class buffers streams into the zip file in

 * {@link DeferredFileOutputStream}s which store data in

 * memory or, if a certain threshold size is exceeded in

 * temporary files.

 * Calling {@link #close()} will write all data into the

 * given defined zip file.

 * Each entry offers its own {@link OutputStream} to write

 * into in parallel.

 *

 * @author a.mueller

 * @since 29.06.2017

 *

 */

public class ZipWriter {

    public static final int DEFAULT_THRESHOLD = 2000000;

    private int threshold = DEFAULT_THRESHOLD;

    private Map<String, DeferredFileOutputStream> entryMap  = new HashMap<>();

    private File tmpFolder = new File(System.getProperty("java.io.tmpdir"));

    private File targetFile;

    /**

     * {@link ZipWriter} with default values.

     *

     * @param targetFile final zip file to be filled

     */

    public ZipWriter(File targetFile) {

        this(targetFile, null, null);

    }

    /**

     * @param targetFile final zip file to be filled

     * @param threshold the threshold when to start writing to file,

     *         uses default (2MB) if  <code>null</code>

     * @param tmpFolder the folder to write the temporary file to

     */

    public ZipWriter(File targetFile, Integer threshold, File tmpFolder) {

        super();

        this.targetFile = targetFile;

        this.threshold = threshold == null ? DEFAULT_THRESHOLD : threshold;

        this.tmpFolder = tmpFolder == null ? this.tmpFolder : tmpFolder;

    }

    public OutputStream getEntryStream(String entryName){

        DeferredFileOutputStream result = entryMap.get(entryName);

        if (result == null){

            result = new DeferredFileOutputStream(threshold, "tmp", "_zip_buffer", tmpFolder);

            entryMap.put(entryName, result);

        }

        return result;

    }

    public void close() throws IOException{

        FileOutputStream fos = new FileOutputStream(targetFile);

        ZipOutputStream zos = new ZipOutputStream(fos);

        for (String key:  entryMap.keySet()){

            ZipEntry zipEntry = new ZipEntry(key);

            zos.putNextEntry(zipEntry);

            DeferredFileOutputStream os = entryMap.get(key);

            os.close();

//            zos.setComment(comment);

            os.writeTo(zos);

            zos.closeEntry();

        }

        try {

            zos.finish();

            zos.close();

        } catch (IOException e) {

            throw e;

        }

        for (String key:  entryMap.keySet()){

            DeferredFileOutputStream os = entryMap.get(key);

            cleanupFile(os);

        }

    }

    private boolean cleanupFile(DeferredFileOutputStream os) {

        try {

            boolean deleted = true;

            File file = os.getFile();

            if (file != null){

                deleted = file.delete();

            }

            return deleted;

        } catch (Exception e) {

            //no matter, it should be in temp folder

            e.printStackTrace();

            return false;

        }

    }

}