/*
    Dateiverwaltung - File management in your browser
    Copyright (C) 2017 Ulrich Hilger, http://uhilger.de

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package de.uhilger.filecms.api;

import de.uhilger.filecms.data.FileRef;
import de.uhilger.filecms.pub.AbstractComparator;
import de.uhilger.filecms.pub.FileNameComparator;
import de.uhilger.filecms.pub.ImgFileFilter;
import de.uhilger.wbx.Bild;
import de.uhilger.wbx.WbxUtils;
import static de.uhilger.wbx.WbxUtils.EMPTY_STRING;
import static de.uhilger.wbx.WbxUtils.WBX_FILE_BASE;
import de.uhilger.wbx.data.Inhalt;
import de.uhilger.wbx.web.TNServlet;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.security.Principal;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.zip.Adler32;
import java.util.zip.CheckedOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;
import javax.servlet.http.HttpServletRequest;
import net.coobird.thumbnailator.Thumbnails;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.filefilter.WildcardFileFilter;
import org.apache.commons.lang.StringEscapeUtils;

/**
 * Methoden zur Verwaltung von Dateien
 */
public class FileMgr extends Api {
  private static final Logger logger = Logger.getLogger(FileMgr.class.getName());
    
  public static final int OP_COPY = 1;
  public static final int OP_MOVE = 2;
  
  public static final String DOT = ".";
  
  public String hallo() {
    return "Hallo Welt!";
  }
  
  /**
   * Inhalte der WebBox listen. Hier wird nur der relative Pfad 
   * ausgehend von www oder home ausgegeben sowie zudem ausgehend 
   * von $daten und $basis, sofern der Benutzer die Rolle wbxAdmin hat.
   * 
   * Andere Inhalte werden nicht ausgegeben.
   * 
   * @param relPath
   * @return 
   */
  public List<FileRef> list(String relPath) {
    return listInt(relPath, "name", AbstractComparator.ORDER_ASC);
  }
  
  public List<FileRef> listOrdered(String relPath, String orderBy, String order) {
    return listInt(relPath, orderBy, order);
  }
  
  /**
   * Inhalte der WebBox listen. Hier wird nur der relative Pfad 
   * ausgehend von www oder home ausgegeben sowie zudem ausgehend 
   * von $daten und $basis, sofern der Benutzer die Rolle wbxAdmin hat.
   * 
   * Andere Inhalte werden nicht ausgegeben.
   * 
   * @param relPath
   * @param orderBy 'name'
   * @param order AbstractComparator.ORDER_ASC oder AbstractComparator.ORDER_DESC
   * @return 
   */
  private List<FileRef> listInt(String relPath, String orderBy, String order) {
    Bild bild = new Bild();
    List<FileRef> files = new ArrayList();
    if (!relPath.startsWith(".") && !relPath.contains("WEB-INF") && !relPath.contains("META-INF")) {
      if (relPath.length() == 0) {
        FileRef namedPublicFolder = new FileRef(PUB_DIR_NAME, true);
        logger.finer(namedPublicFolder.getAbsolutePath());
        FileRef namedHomeFolder = new FileRef(HOME_DIR_NAME, true);
        logger.finer(namedHomeFolder.getAbsolutePath());
        FileRef namedDavFolder = new FileRef(DAV_DIR_NAME, true);
        logger.finer(namedDavFolder.getAbsolutePath());
        files = new ArrayList();
        files.add(namedHomeFolder);
        files.add(namedPublicFolder);
        files.add(namedDavFolder);
        if (getRequest().isUserInRole(WBX_ADMIN_ROLE)) {
          FileRef namedBaseFolder = new FileRef(WBX_BASE, true);
          FileRef namedDataFolder = new FileRef(WBX_DATA, true);
          files.add(namedBaseFolder);
          files.add(namedDataFolder);
        }
      } else {
        String path = getTargetDir(relPath).getAbsolutePath();
        logger.fine("listing path: " + path);
        File dir = new File(path);
        if (dir.exists()) {
          File[] fileArray = dir.listFiles(new ImgFileFilter());
          if (orderBy != null && orderBy.equalsIgnoreCase("name")) {
            Arrays.sort(fileArray, new FileNameComparator(order));
          } else {
            Arrays.sort(fileArray, new FileNameComparator(AbstractComparator.ORDER_ASC));
          }
          for (int i = 0; i < fileArray.length; i++) {
            logger.fine(fileArray[i].toURI().toString());
            String fname = fileArray[i].toURI().toString().replace("file:/", "");
            if (fileArray[i].isDirectory()) {
              fname = fname.substring(0, fname.length() - 1);
            }
            logger.fine(fname);
            if(!fname.contains("WEB-INF") && !fname.contains("META-INF")) {
              long fLen = fileArray[i].length();
              long lastMod = fileArray[i].lastModified();
              FileRef ref = new FileRef(fname, fileArray[i].isDirectory(), fileArray[i].isHidden(), lastMod, fLen);
              ref.setMimetype(bild.getMimeType(fileArray[i]));
              files.add(ref);
            }
          }
        }
      }
    }
    return files;
  }

  public List<Inhalt> collect(String relativePath, int maxTiefe, int maxAnzahl, int len) {
    
    WbxUtils wu = new WbxUtils();
    HttpServletRequest req = getRequest();
    String requestUrl = req.getRequestURL().toString();
    String contextPath = req.getContextPath();
    return wu.collectFiles(requestUrl, contextPath, relativePath, maxTiefe, maxAnzahl, len);
  }
  
  public FileRef newFolder(String relPath, String folderName) {
    if (!relPath.startsWith(".")) {
      logger.finer(relPath);
      String targetPath = null;
      if(relPath.startsWith(PUB_DIR_NAME)) {
        targetPath = PUB_DIR_PATH + getUserName() + "/" + relPath.substring(PUB_DIR_NAME.length()) + "/" + folderName;
      } else if(relPath.startsWith(HOME_DIR_NAME)) {
        targetPath = HOME_DIR_PATH + getUserName() + "/" + relPath.substring(HOME_DIR_NAME.length()) + "/" + folderName;
      } else {
        // kann eigentlich nicht sein..
      }
      logger.finer(targetPath);
      File targetDir = new File(getBase().getAbsolutePath(), targetPath);
      targetDir.mkdirs();
      return new FileRef(targetDir.getAbsolutePath(), true);
    } else {
      return null;
    }
  }
  
  public String getCode(String relPath, String fileName) {
    String code = null;
    if (!relPath.startsWith(".")) {
      Object p = getRequest().getUserPrincipal();
      if (p instanceof Principal) {
        Reader reader = null;
        try {
          File targetFile = new File(getTargetDir(relPath), fileName);

          reader = new InputStreamReader(new FileInputStream(targetFile), Charset.forName("UTF-8").newDecoder());
          //reader = new FileReader(targetFile);
          StringBuffer buf = new StringBuffer();
          char[] readBuffer = new char[1024];
          int charsRead = reader.read(readBuffer);
          while (charsRead > -1) {
            buf.append(readBuffer, 0, charsRead);
            charsRead = reader.read(readBuffer);
          }
          code = buf.toString();
        } catch (FileNotFoundException ex) {
          Logger.getLogger(FileMgr.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
          Logger.getLogger(FileMgr.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
          try {
            reader.close();
          } catch (IOException ex) {
            Logger.getLogger(FileMgr.class.getName()).log(Level.SEVERE, null, ex);
          }
        }

      }
    }
    return code;
  }
  
  public String renameFile(String relPath, String fname, String newName) {
    if (!relPath.startsWith(".")) {
      File targetDir = getTargetDir(relPath);
      File file = new File(targetDir, fname);
      if(fname.endsWith(TNServlet.JPEG) || fname.endsWith(TNServlet.JPG) || fname.endsWith(TNServlet.PNG)) {
        renameImgFiles(targetDir, file, newName);  
      } else {
        file.renameTo(new File(targetDir, newName));
      }
      return fname + " umbenannt zu " + newName;
    } else {
      return "Pfad nicht erlaubt.";
    }
  }
  
  public void renameImgFiles(File targetDir, File targetFile, String newName) {
    String alt;
    String neu;
    
    int newdotpos = newName.lastIndexOf(DOT);
    String newfname = newName.substring(0, newdotpos);
    String newext = newName.substring(newdotpos);
    logger.fine("newfname: " + newfname + ", newext: " + newext);
    
    String fnameext = targetFile.getName();
    int dotpos = fnameext.lastIndexOf(DOT);
    String fname = fnameext.substring(0, dotpos);
    String ext = fnameext.substring(dotpos);
    logger.fine("fname: " + fname + ", ext: " + ext);
    
    FileFilter fileFilter = new WildcardFileFilter(fname + "*" + ext);
    File[] files = targetDir.listFiles(fileFilter);
    for (int i = 0; i < files.length; i++) {
      alt = files[i].getName();
      logger.fine("alt: " + alt);
      if(alt.contains(TNServlet.TN)) {
        neu = newfname + TNServlet.TN + newext;
      } else if (alt.contains(TNServlet.KL)) {
        neu = newfname + TNServlet.KL + newext;
      } else if(alt.contains(TNServlet.GR)) {
        neu = newfname + TNServlet.GR + newext;
      } else if(alt.contains(TNServlet.MT)) {
        neu = newfname + TNServlet.MT + newext;
      } else if(alt.contains(TNServlet.SM)) {
        neu = newfname + TNServlet.SM + newext;
      } else {
        neu = newName;
      }
      files[i].renameTo(new File(targetDir, neu));        
      logger.fine("neu: " + neu);
    }      
  }
  
  public String deleteFiles(String relPath, List fileNames) {
    String result = null;
    try {
      logger.fine(fileNames.toString());
      if (!relPath.startsWith(DOT)) {
        File targetDir = getTargetDir(relPath);
        for(int i=0; i < fileNames.size(); i++) {
          Object o = fileNames.get(i);
          if(o instanceof ArrayList) {
            ArrayList al = (ArrayList) o;
            logger.fine(al.get(0).toString());
            File targetFile = new File(targetDir, al.get(0).toString());
            logger.fine(targetFile.getAbsolutePath());
            if(targetFile.isDirectory()) {
              FileUtils.deleteDirectory(targetFile);
            } else {
                /*
                Wenn targetFile mit jpg, jpeg oder png endet, 
                muss eine Unterfunktion eine Liste aller Dateien bilden, 
                die so heissen, also z.B. alle [Dateiname]*.jpg
                */
              String fname = targetFile.getName().toLowerCase();
              if(fname.endsWith(TNServlet.JPEG) || fname.endsWith(TNServlet.JPG) || fname.endsWith(TNServlet.PNG)) {
                deleteImgFiles(targetDir, targetFile);  
              } else {
                targetFile.delete();
              }
            }
          }
        }
        result = "deleted";
      }
    } catch (Throwable ex) {
      logger.log(Level.SEVERE, ex.getLocalizedMessage(), ex);
    }
    return result;
  }
  
  public void deleteImgFiles(File targetDir, File targetFile) {
    String fnameext = targetFile.getName();
    int dotpos = fnameext.lastIndexOf(DOT);
    String fname = fnameext.substring(0, dotpos);
    String ext = fnameext.substring(dotpos);
    logger.fine("fname: " + fname + ", ext: " + ext);
    FileFilter fileFilter = new WildcardFileFilter(fname + "*" + ext);
    File[] files = targetDir.listFiles(fileFilter);
    for (int i = 0; i < files.length; i++) {
        logger.fine(files[i].getName());
        files[i].delete();
    }      
  }
  
  public String copyFiles(String fromPath, String toPath, List fileNames) {
    return copyOrMoveFiles(fromPath, toPath, fileNames, OP_COPY);
  }
  
  public String moveFiles(String fromPath, String toPath, List fileNames) {
    return copyOrMoveFiles(fromPath, toPath, fileNames, OP_MOVE);
  }
  
  public String duplicateFile(String fromPath, String fileName) {
    String result = null;
    try {
      File srcDir = getTargetDir(fromPath);
      File srcFile = new File(srcDir, fileName);
      String fnameext = srcFile.getName();
      int dotpos = fnameext.lastIndexOf(DOT);
      String fname = fnameext.substring(0, dotpos);
      String ext = fnameext.substring(dotpos);
      File destFile = new File(srcDir, fname + "-Kopie" + ext);
      int i = 1;
      while(destFile.exists()) {
        destFile = new File(srcDir, fname + "-Kopie-" + Integer.toString(++i) + ext);
      }
      FileUtils.copyFile(srcFile, destFile);
      result = destFile.getName();
    } catch (IOException ex) {
      logger.log(Level.SEVERE, ex.getLocalizedMessage(), ex);
    }
    return result;
  }
  
  private String copyOrMoveFiles(String fromPath, String toPath, List fileNames, int operation) {
    String result = null;
    try {
      if (!fromPath.startsWith(".")) {
        File srcDir = getTargetDir(fromPath);
        File targetDir = getTargetDir(toPath);
        Iterator i = fileNames.iterator();
        while(i.hasNext()) {
          Object o = i.next();
          if (o instanceof ArrayList) {
            ArrayList al = (ArrayList) o;
            File srcFile = new File(srcDir, al.get(0).toString());
            if(srcFile.isDirectory()) {
              if(operation == OP_MOVE) {
                FileUtils.moveDirectoryToDirectory(srcFile, targetDir, false);
              } else {
                FileUtils.copyDirectoryToDirectory(srcFile, targetDir);
              }
            } else {
              if(operation == OP_MOVE) {
                String fname = srcFile.getName().toLowerCase();                
                if(fname.endsWith(TNServlet.JPEG) || fname.endsWith(TNServlet.JPG) || fname.endsWith(TNServlet.PNG)) {
                  moveImgFilesToDirectory(srcFile, srcDir, targetDir, false);
                } else {
                  FileUtils.moveFileToDirectory(srcFile, targetDir, false);
                }
              } else {
                FileUtils.copyFileToDirectory(srcFile, targetDir);              
              }
            }
          }
        }
      }
    } catch (IOException ex) {
      logger.log(Level.SEVERE, ex.getLocalizedMessage(), ex);
    }
    return result;
  }
  
  private void moveImgFilesToDirectory(File srcFile, File srcDir, File targetDir, boolean createDestDir) throws IOException {
    String fnameext = srcFile.getName();
    int dotpos = fnameext.lastIndexOf(DOT);
    String fname = fnameext.substring(0, dotpos);
    String ext = fnameext.substring(dotpos);
    logger.fine("fname: " + fname + ", ext: " + ext);
    FileFilter fileFilter = new WildcardFileFilter(fname + "*" + ext);
    File[] files = srcDir.listFiles(fileFilter);
    for (int i = 0; i < files.length; i++) {
      logger.fine(files[i].getName());
      FileUtils.moveFileToDirectory(files[i], targetDir, createDestDir);
    }      
  }
  
  public FileRef saveTextFileAs(String relPath, String fileName, String contents) {
    FileRef savedFile = null;
    logger.fine(relPath + " " + fileName);
    if (!relPath.startsWith(".")) {
      //FileRef datenRef = getBase();
      Object p = getRequest().getUserPrincipal();
      if(p instanceof Principal) {
        File targetFile = new File(getTargetDir(relPath), fileName);
        if(targetFile.exists()) {
          targetFile = getNewFileName(targetFile);
        } else {
          targetFile.getParentFile().mkdirs();
        }
        saveToFile(targetFile, contents);
      }
    }
    return savedFile;
  }
  
  private File getNewFileName(File file) {
    File dir = file.getParentFile();
    String targetName = file.getName();
    logger.fine("targetName: " + targetName);
    String ext = "";
    int dotpos = targetName.indexOf(".");
    if(dotpos > -1) {
      ext = targetName.substring(dotpos);
      targetName = targetName.substring(0, dotpos);
    }
    logger.fine("targetName: " + targetName + ", ext: " + ext);
    int i = 1;
    while(file.exists()) {
      StringBuffer buf = new StringBuffer();
      buf.append(targetName);
      buf.append("-");
      buf.append(i);
      if(ext.length() > 0) {
        buf.append(ext);
      }
      file = new File(dir, buf.toString());
      i++;
    }
    logger.fine("new file: " + file.getName());
    return file;
  }  
  
  private FileRef saveToFile(File targetFile, String contents) {
    FileRef savedFile = null;
    try {
      targetFile.createNewFile();
      //FileWriter w = new FileWriter(targetFile, Charset.forName("UTF-8"));
      //w.write(StringEscapeUtils.unescapeHtml(contents));
      Writer w = new OutputStreamWriter(new FileOutputStream(targetFile), "UTF-8");
      //w.write(contents);
      w.write(StringEscapeUtils.unescapeHtml(contents));
      w.flush();
      w.close();
      savedFile = new FileRef(
              targetFile.getAbsolutePath(),
              targetFile.isDirectory(),
              targetFile.isHidden(),
              targetFile.lastModified(),
              targetFile.length());
    } catch (IOException ex) {
      logger.log(Level.SEVERE, ex.getLocalizedMessage(), ex);
    }
    return savedFile;
  }
  
  public FileRef saveTextFile(String relPath, String fileName, String contents) {
    FileRef savedFile = null;
    logger.fine(relPath + " " + fileName);
    if (!relPath.startsWith(".")) {    
      //FileRef datenRef = getBase();
      Object p = getRequest().getUserPrincipal();
      if(p instanceof Principal) {
        File targetFile = new File(getTargetDir(relPath), fileName);
        if(targetFile.exists()) {
          /*
            muss delete() sein?
            pruefen: ueberschreibt der FileWriter den alteen Inhalt oder 
            entsteht eine unerwuenschte Mischung aus altem und neuem 
            Inhalt?
          */
          targetFile.delete();
        } else {
          targetFile.getParentFile().mkdirs();
        }
        saveToFile(targetFile, contents);
      }
    }
    return savedFile;
  }
  
  public String bildVerkleinern(String relPath, String bildName) {
    if (!relPath.startsWith(".")) {
      File dir = getTargetDir(relPath);
      File original = new File(dir, bildName);
      Bild bild = new Bild();
      //for (int i = 0; i < Bild.GR.length; i++) {

      //int gr = bild.getVariantenGroesse(i);
      String ext = "";
      String nurname = bildName;
      int dotpos = bildName.indexOf(".");
      if (dotpos > -1) {
        ext = bildName.substring(dotpos);
        nurname = bildName.substring(0, dotpos);
      }

          // 120, 240, 500, 700, 1200

      
      for (int i = 0; i < Bild.GR.length; i++) {
        StringBuffer buf = new StringBuffer();
        buf.append(nurname);
        buf.append(bild.getVariantenName(i));
        buf.append(ext);
        File newImgFile = new File(dir, buf.toString());
        try {
          Thumbnails.of(original)
                  .size(bild.getVariantenGroesse(i), bild.getVariantenGroesse(i))
                  .keepAspectRatio(true)
                  .outputQuality(0.7)
                  .toFile(newImgFile);
        } catch (IOException ex) {
          logger.log(Level.SEVERE, ex.getLocalizedMessage(), ex);
        }
      }
      return "ok";
    } else {
      return "Pfad micht erlaubt.";
    }
  }
  
  public String bildRotieren(String relPath, String bildName) {
    if (!relPath.startsWith(".")) {
      File dir = getTargetDir(relPath);
      File original = new File(dir, bildName);

      String ext = "";
      String nurname = bildName;
      int dotpos = bildName.indexOf(".");
      if (dotpos > -1) {
        ext = bildName.substring(dotpos);
        nurname = bildName.substring(0, dotpos);
      }

      StringBuffer buf = new StringBuffer();
      buf.append(nurname);
      buf.append("-rot");
      buf.append(ext);
      File newImgFile = new File(dir, buf.toString());
      
      logger.fine("original: " + original.getAbsolutePath() + " newImgFile: " + newImgFile.getAbsolutePath());

      try {
        Thumbnails.of(original)
                .scale(1)
                .rotate(90)
                .toFile(newImgFile);
      } catch (IOException ex) {
        logger.log(Level.SEVERE, ex.getLocalizedMessage(), ex);
      }


      return "ok";
    } else {
      return "Pfad micht erlaubt.";
    }
  }
  
  /* --------- ZIP entpacken ---------------- */
  
  public String extractZipfile(String relPath, String filename) {
    String result = null;
    if (!relPath.startsWith(".")) {    
      try {
        File targetDir = getTargetDir(relPath);
        File archive = new File(targetDir, filename);
        if(extract(archive)) {
          result = "ok";
        } else {
          result = "error while extracting";
        }
      } catch(Exception ex) {
        result = ex.getLocalizedMessage();
        logger.log(Level.SEVERE, ex.getLocalizedMessage(), ex);
      }
    }
    return result;
  }
  
  /**
	 * extract a given ZIP archive to the folder respective archive resides in
	 * @param archive  the archive to extract
	 * @throws Exception
	 */
	private boolean extract(File archive) throws Exception {
		ZipFile zipfile = new ZipFile(archive);
		Enumeration en = zipfile.entries();
		while(en.hasMoreElements()) {
			ZipEntry zipentry = (ZipEntry) en.nextElement();
			unzip(zipfile, zipentry, archive.getParent());
		}
		zipfile.close();
		return true;
	}

	/**
	 * unzip a given entry of a given zip file to a given location
	 * @param zipfile  the zip file to read an entry from
	 * @param zipentry  the zip entry to read
	 * @param destPath  the path to the destination location for the extracted content
	 * @throws IOException
	 */
	private void unzip(ZipFile zipfile, ZipEntry zipentry, String destPath) throws IOException {
		byte buf[] = new byte[1024];
		InputStream is = zipfile.getInputStream(zipentry);
		String outFileName = destPath + File.separator + zipentry.getName();
		File file = new File(outFileName);
		if(!zipentry.isDirectory()) {
			file.getParentFile().mkdirs();
			if(!file.exists())
				file.createNewFile();
			FileOutputStream fos = new FileOutputStream(file);
			int i = is.read(buf, 0, 1024);
			while(i > -1) {
				fos.write(buf, 0, i);
				i = is.read(buf, 0, 1024);
			}
			fos.close();
			is.close();
		} else {
			file.mkdirs();
		}
	}

  /* ------------- Ornder als ZIP packen --------------- */
  
  public String packFolder(String relPath) {
    if (!relPath.startsWith(".")) {    
      try {
        File targetDir = getTargetDir(relPath);
        File parentDir = targetDir.getParentFile();
        StringBuffer fname = new StringBuffer();
        fname.append(targetDir.getName());
        fname.append(".zip");
        File archiveFile = new File(parentDir, fname.toString());
        FileRef folderToPack = new FileRef(targetDir.getAbsolutePath());
        FileRef archive = new FileRef(archiveFile.getAbsolutePath());
        pack(folderToPack, archive);
        return "ok";
      } catch(Exception ex) {
        String result = ex.getLocalizedMessage();
        logger.log(Level.SEVERE, result, ex);
        return result;
      }
    } else {
      return "Falsche relative Pfadangabe";
    }
  }
  
	/**
	 * pack the contents of a given folder into a new ZIP compressed archive
	 * @param folder  the folder to pack
	 * @param archive  the archive to create from the given files
	 * @throws Exception
	 */
	private boolean pack(FileRef folder, FileRef archive) throws Exception {
		File file = new File(archive.getAbsolutePath());
		FileOutputStream fos = new FileOutputStream(file);
		CheckedOutputStream checksum = new CheckedOutputStream(fos, new Adler32());
		ZipOutputStream zos = new ZipOutputStream(checksum);
		pack(zos, folder.getAbsolutePath(), "");
		zos.flush();
		zos.finish();
		zos.close();
		fos.flush();
		fos.close();
		return true;
	}

	/**
	 * go through the given file structure recursively
	 * @param zipFile  the ZIP file to write to
	 * @param srcDir  the directory to pack during this cycle
	 * @param subDir  the subdirectory to append to names of file entries inside the archive
	 * @throws IOException
	 */
	private void pack(ZipOutputStream zipFile, String srcDir, String subDir) throws IOException {
		File[] files = new File(srcDir).listFiles();
		for(int i = 0; i < files.length; i++) {
			if(files[i].isDirectory()) {
				pack(zipFile, files[i].getAbsolutePath(), subDir + File.separator + files[i].getName());
			}
			else {
				packFile(zipFile, subDir, files[i]);
			}
		}
	}

	/**
	 * pack a given file
	 * @param zipFile  the ZIP archive to pack to
	 * @param dir  the directory name to append to name of file entry inside archive
	 * @param file  the file to pack
	 * @throws IOException
	 */
	private void packFile(ZipOutputStream zipFile, String dir, File file) throws IOException
	{
		FileInputStream fileinputstream = new FileInputStream(file);
		byte buf[] = new byte[fileinputstream.available()];
		fileinputstream.read(buf);
		String dirWithSlashes = dir.replace('\\', '/');
		//System.out.println("zipping " + dirWithSlashes + "/" + file.getName());
		ZipEntry ze = new ZipEntry(dirWithSlashes + "/" + file.getName());
		ze.setMethod(ZipEntry.DEFLATED);
		zipFile.putNextEntry(ze);
		zipFile.write(buf, 0, buf.length);
		zipFile.closeEntry();
		fileinputstream.close();
	}

  

  /* ---- Hilfsfunktionen ---- */
  
}