/*
  fm - File management class library
  Copyright (C) 2024  Ulrich Hilger

  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 <https://www.gnu.org/licenses/>.
 */
package de.uhilger.fm;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

/**
 * Entpacken von Dateien
 *
 * @author Ulrich Hilger, 15. Januar 2024
 */
public class Inflator {

  /**
   * Eine Zip-Datei entpacken
   * 
   * @param fName Name der Zip-Datei
   * @param base absoluter Pfad des Ablageortes der Zip-Datei
   * @return 'ok', wenn erfolgreich oder Fehlermeldung, wenn nicht
   */
  public String extractZipfile(String fName, /*String relPath, */String base) {
    //logger.fine("fName: " + fName + ", relPath: " + relPath);
    String result = null;
//    if (!relPath.startsWith(".")) {
      try {
        //File targetDir = new File(fileBase, relPath);
        //File targetDir = getTargetDir(relPath);
        File archive = new File(base, fName);
        if (extract(archive)) {
          result = "ok";
        } else {
          result = "error while extracting";
        }
      } catch (Exception ex) {
        result = ex.getLocalizedMessage();
        //logger.log(Level.SEVERE, ex.getLocalizedMessage(), ex);
      }
//    } else {
//      result = "Falsche relative Pfadangabe.";
//    }
    return result;
  }

  /**
   * Eine Datei in den Ordner entpacken, in dem sie liegt
   *
   * @param archive die zu entpackende Zip-Datei
   * @throws Exception wenn etwas schief geht
   */
  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
   * Einen Eintrag in einer ZIP-Datei an einen gegebenen Ausgabeort extrahieren
   *
   * @param zipfile die Zip-Datei, aus der ein zu entpackender Eintrag gelesen werden soll
   * @param zipentry der Eintrag, der entpackt werden soll
   * @param destPath der Pfad zum Ausgabeort
   * @throws IOException wenn etwas schief geht
   */
  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();
    }
  }

}