/**
    * This file Copyright (c) 2015-2017 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.ui.framework.util;
  
  import info.magnolia.cms.core.Path;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.vaadin.server.DownloadStream;
  import com.vaadin.server.StreamResource;
  
  /**
   * {@link StreamSource} version which organises streaming via a temporary file.
   *
   * Streamed content can be populated via {@link OutputStream} provided by {@link #getTempFileOutputStream()}.
   * In order to set up the resource the following attributes are required to be set:
   * <ul>
   * <li>tempFileName - name of the buffer temporary file</li>
   * <li>tempFileExtension - extension of the buffer temporary file</li>
   * <li>fileName - the name of the downloaded file</li>
   * </ul>
   *
   * <strong>Note:</strong> the streamed resource is by default configured to be not cached
   * <strong>Note:</strong> the temporary file is attempted to be eagerly deleted once the streaming is over
   */
  public class TempFileStreamResource extends StreamResource {
  
      private static final Logger log = LoggerFactory.getLogger(TempFileStreamResource.class);
  
      public TempFileStreamResource(String filename) {
          super(new TempFileStreamSource(), filename);
          setCacheTime(-1);
      }
  
      public TempFileStreamResource() {
          this(null);
      }
  
      @Override
      public TempFileStreamSource getStreamSource() {
          return (TempFileStreamSource) super.getStreamSource();
      }
  
      @Override
      public DownloadStream getStream() {
          final DownloadStream stream = super.getStream();
          if (!StringUtils.isBlank(getFilename())) {
              stream.setParameter("Content-Disposition", "attachment;filename=\"" + getFilename() + "\"");
          }
          return stream;
      }
  
      public void setTempFileName(String name) {
          getStreamSource().tempFileName = name;
      }
  
      public void setTempFileExtension(String extension) {
          getStreamSource().tempFileExtension = extension;
     }
 
     public OutputStream getTempFileOutputStream() throws IOException {
         return getStreamSource().getOutputStream();
     }
 
     private static class TempFileStreamSource implements StreamSource {
 
         private String tempFileName;
 
         private String tempFileExtension;
 
         private File tempFile = null;
 
         private FileOutputStream fileOutputStream = null;
 
         @Override
         public InputStream getStream() {
             try {
                 return new DeleteOnCloseFileInputStream(tempFile);
             } catch (FileNotFoundException e) {
                 return null;
             }
         }
 
         OutputStream getOutputStream() throws IOException {
             if (fileOutputStream == null) {
                 fileOutputStream = new FileOutputStream(getTempFile());
             }
             return fileOutputStream;
         }
 
         File getTempFile() throws IOException {
             if (tempFile == null) {
                 // Create a temporary file that will hold the data created by the export command.
 
                 tempFile = File.createTempFile(tempFileName, tempFileExtension, Path.getTempDirectory());
 
             }
             return tempFile;
         }
     }
 
     private static class DeleteOnCloseFileInputStream extends FileInputStream {
 
         private File file;
 
         public DeleteOnCloseFileInputStream(File file) throws FileNotFoundException {
             super(file);
             this.file = file;
         }
 
         @Override
         public void close() throws IOException {
             super.close();
             if (file.exists() && !file.delete()) {
                 log.warn("Could not delete temporary export file {}", file.getAbsolutePath());
             }
         }
 
     }
 }