/*
    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 static de.uhilger.filecms.api.FileMgr.HOME_DIR_NAME;
import static de.uhilger.filecms.api.FileMgr.HOME_DIR_PATH;
import static de.uhilger.filecms.api.FileMgr.PUB_DIR_NAME;
import static de.uhilger.filecms.api.FileMgr.PUB_DIR_PATH;
import de.uhilger.filecms.web.Initialiser;
import de.uhilger.filesystem.FileRef;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.security.Principal;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.FileCleanerCleanup;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.FileCleaningTracker;

/**
 * Objekte der Klasee UploadServlet nehmen eine Datei per HTTP Multipart Request
 * entgegen und speichern sie im webapps-Verzeichnis des Servlet-Containers.
 *
 * Annahme ist, dass das von javax.servlet.context.tempdir bezeichnete
 * Verzeichnis auf CATALINA_BASE/work/Catalina/localhost/[context] zeigt. Von
 * dort wird dann das webapps-Verzeichnis als CATALINA_BASE/webapps ermittelt.
 */
public class UploadServlet extends HttpServlet {

  public static final String DESC = "file-cms uploader";

  private static final Logger logger = Logger.getLogger(UploadServlet.class.getName());
  
  private String targetDirStr;

  /**
   * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
   * methods.
   *
   * @param request servlet request
   * @param response servlet response
   * @throws ServletException if a servlet-specific error occurs
   * @throws IOException if an I/O error occurs
   */
  protected void processRequest(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException {
    
    //logger.log(Level.INFO, "start");
    boolean isMultipart = ServletFileUpload.isMultipartContent(request);

    if (isMultipart) {
      //logger.log(Level.INFO, "isMultipart");
      try {
        ServletContext servletContext = this.getServletConfig().getServletContext();

        // Configure a repository (to ensure a secure temp location is used)
        File repository = (File) servletContext.getAttribute("javax.servlet.context.tempdir");
        // CATALINA_BASE/work/Catalina/localhost/wbx

        // Create a factory for disk-based file items
        DiskFileItemFactory factory = newDiskFileItemFactory(servletContext, repository);

        // Create a new file upload handler
        ServletFileUpload upload = new ServletFileUpload(factory);

        // Parse the request
        List<FileItem> items = upload.parseRequest(request);

        // Process the uploaded items
        Iterator<FileItem> iter = items.iterator();
        FileItem fileItem = null;
        while (iter.hasNext()) {
          FileItem item = iter.next();

          if (item.isFormField()) {
            processFormField(item);
          } else {
            //File base = repository.getParentFile().getParentFile().getParentFile().getParentFile();
            //File webapps = new File(base, "webapps");
            //logger.info(webapps.getAbsolutePath());
            fileItem = item;
          }
        }
        File targetDir = getTargetDir(request, targetDirStr);
        if(targetDir != null && fileItem != null) {
          logger.log(Level.FINER, "targetDir before upload: " + targetDir.getAbsolutePath());
          processUploadedFile(targetDir, fileItem, true);
        }
      } catch (Exception ex) {
        logger.log(Level.SEVERE, null, ex);
      }
    } else {
      // kein Upload
    }

    /*
    response.setContentType("text/html;charset=UTF-8");
    try (PrintWriter out = response.getWriter()) {
      out.println("<!DOCTYPE html>");
      out.println("<html>");
      out.println("<head>");
      out.println("<title>Servlet UploadServlet</title>");      
      out.println("</head>");
      out.println("<body>");
      out.println("<h1>Servlet UploadServlet at " + request.getContextPath() + "</h1>");
      out.println("</body>");
      out.println("</html>");
    }
     */
  }

  private File getTargetDir(HttpServletRequest request, String relPath) {
    File targetDir = null;
    if(relPath != null) {
      logger.finer(relPath);
      String targetPath = null;
      if(relPath.startsWith(PUB_DIR_NAME)) {
        targetPath = PUB_DIR_PATH + getUserName(request) + relPath.substring(PUB_DIR_NAME.length());
      } else if(relPath.startsWith(HOME_DIR_NAME)) {
        targetPath = HOME_DIR_PATH + getUserName(request) + relPath.substring(HOME_DIR_NAME.length());
      } else {
        // kann eigentlich nicht sein..
      }
      logger.finer(targetPath);
      targetDir = new File(getBase().getAbsolutePath(), targetPath);
    }
    return targetDir;
  }
  
  private String getUserName(HttpServletRequest request) {
    String userName = null;
    Object p = request.getUserPrincipal();
    if (p instanceof Principal) {
      userName = ((Principal) p).getName();
    }
    return userName;
  }

  private FileRef getBase() {
    FileRef base = null;
    Object o = getServletContext().getAttribute(Initialiser.FILE_BASE);
    if (o instanceof FileRef) {
      base = (FileRef) o;
    }
    return base;
  }

  private void processUploadedFile(File targetDir, FileItem item, boolean writeToFile) throws Exception {
    //logger.log(Level.INFO, "start");
    // Process a file upload
    if (!item.isFormField()) {
      String fieldName = item.getFieldName();
      String fileName = item.getName();
      String contentType = item.getContentType();
      boolean isInMemory = item.isInMemory();
      long sizeInBytes = item.getSize();
      // Process a file upload
      if (writeToFile) {
        File uploadedFile = new File(targetDir, fileName);
        logger.log(Level.FINER, "writeToFile " + uploadedFile.getAbsolutePath());
        item.write(uploadedFile);
      } else {
        InputStream uploadedStream = item.getInputStream();
        //...
        uploadedStream.close();
      }
    }
  }

  private void processFormField(FileItem item) {
    //logger.log(Level.INFO, "start");
    // Process a regular form field
    if (item.isFormField()) {
      String name = item.getFieldName();
      String value = item.getString();
      logger.log(Level.FINER, "field name: " + name + ", value: " + value);
      //...
      if(name.equals("pfad")) {
        targetDirStr = value;
      }
    }
  }

  public static DiskFileItemFactory newDiskFileItemFactory(ServletContext context,
          File repository) {
    FileCleaningTracker fileCleaningTracker
            = FileCleanerCleanup.getFileCleaningTracker(context);
    DiskFileItemFactory factory
            = new DiskFileItemFactory(DiskFileItemFactory.DEFAULT_SIZE_THRESHOLD,
                    repository);
    factory.setFileCleaningTracker(fileCleaningTracker);
    return factory;
  }

  // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
  /**
   * Handles the HTTP <code>GET</code> method.
   *
   * @param request servlet request
   * @param response servlet response
   * @throws ServletException if a servlet-specific error occurs
   * @throws IOException if an I/O error occurs
   */
  @Override
  protected void doGet(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException {
    processRequest(request, response);
  }

  /**
   * Handles the HTTP <code>POST</code> method.
   *
   * @param request servlet request
   * @param response servlet response
   * @throws ServletException if a servlet-specific error occurs
   * @throws IOException if an I/O error occurs
   */
  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException {
    processRequest(request, response);
  }

  /**
   * Returns a short description of the servlet.
   *
   * @return a String containing servlet description
   */
  @Override
  public String getServletInfo() {
    return DESC;
  }// </editor-fold>

}