/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.exoplatform.commons.utils;

import eu.medsea.mimeutil.MimeUtil;

import org.exoplatform.services.log.ExoLogger;
import org.exoplatform.services.log.Log;

import java.io.IOException;
import java.io.InputStream;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;

public class MimeTypeResolver
{
   protected static Log log = ExoLogger.getLogger("org.exoplatform.commons.utils.MimeTypeResolver");

   static {
      SecurityHelper.doPrivilegedAction(new PrivilegedAction<Void>()
      {
         public Void run()
         {
            MimeUtil.registerMimeDetector("eu.medsea.mimeutil.detector.MagicMimeMimeDetector");
            return null;
         }
      });
   }

   private Map<String, List<String>> mimeTypes = new HashMap<String, List<String>>();

   private Map<String, List<String>> extentions = new HashMap<String, List<String>>();

   private String defaultMimeType = "application/octet-stream";

   public MimeTypeResolver()
   {
      try
      {
         SecurityHelper.doPrivilegedIOExceptionAction(new PrivilegedExceptionAction<Void>()
         {
            public Void run() throws Exception
            {
               Scanner scanner = null;
               String mimeTypeProperties = System.getProperty("org.exoplatform.mimetypes");
               if (mimeTypeProperties != null)
               {
                  InputStream stream =
                     Thread.currentThread().getContextClassLoader().getResourceAsStream(mimeTypeProperties);
                  if (stream != null)
                  {
                     scanner = new Scanner(stream, "ISO-8859-1");
                  }
               }
               if (scanner == null)
               {
                  scanner = new Scanner(getClass().getResourceAsStream("mimetypes.properties"), "ISO-8859-1");
               }
               try
               {
                  while (scanner.hasNextLine())
                  {
                     processLine(scanner.nextLine());
                  }
               }
               finally
               {
                  scanner.close();
               }

               return null;
            }
         });
      }
      catch (IOException e)
      {
         throw new InternalError("Unable to load mimetypes: " + e.toString());
      }
   }

   /**
    * Returns default MIMEType.
    * 
    * @return String
    */
   public String getDefaultMimeType()
   {
      return defaultMimeType;
   }

   /**
    * Set default MIMEType.
    * 
    * @param defaultMimeType
    *          String, default MIMEType
    */
   public void setDefaultMimeType(String defaultMimeType)
   {
      this.defaultMimeType = defaultMimeType;
   }

   /**
    * Get MIMEType which corresponds to file extension. If file extension is unknown the default 
    * MIMEType will be returned. If there are more than one MIMETypes for specific extension the 
    * first occurred in the list will be returned. 
    * 
    * @param filename
    * @return String MIMEType
    */
   public String getMimeType(String filename)
   {
      String ext = filename.substring(filename.lastIndexOf(".") + 1);
      if (ext.isEmpty())
      {
         ext = filename;
      }

      List<String> values = mimeTypes.get(ext);
      return values == null ? defaultMimeType : values.get(0);
   }

   /**
    * Get MIMEType which corresponds to file content. If file content 
    * does not allow to determine MIMEtype, the default MIMEType will be returned. 
    *
    * @param fileName
    * @param is
    * @return String MIMEType
    */
   public String getMimeType(String fileName, InputStream is)
   {
      String mimeType = getMimeType(fileName);

      if (mimeType == defaultMimeType)
      {
         Collection<?> mimeTypes = MimeUtil.getMimeTypes(is);
         if (!mimeTypes.isEmpty())
         {
            mimeType = mimeTypes.toArray()[0].toString();
         }
      }

      return mimeType;
   }

   /**
    * Get file extension corresponds to MIMEType. If MIMEType is empty or equals
    * default MIMEType empty string will be returned. If there is no file extension
    * for specific MIMEType the empty string will be returned also. In case when 
    * there are more than one extension for specific MIMEType the first occurred 
    * extension in the list will be returned if MIMEType ends with this extension
    * otherwise just first occurred.
    * 
    * @param mimeType
    *          MIMEType
    * @return file extension
    */
   public String getExtension(String mimeType)
   {
      if (mimeType.isEmpty() || mimeType.equals(defaultMimeType))
      {
         return "";
      }

      List<String> values = extentions.get(mimeType);
      if (values == null)
      {
         return "";
      }

      String resultExt = "";
      for (String ext : values)
      {
         if (mimeType.endsWith(ext))
         {
            return ext;
         }

         if (resultExt.isEmpty())
         {
            resultExt = ext;
         }
      }
      return resultExt;
   }

   /**
    * Load MIMEType and corresponding extension.
    * 
    * @param aLine
    */
   protected void processLine(String aLine)
   {
      int p = aLine.indexOf("=");

      String ext = aLine.substring(0, p);
      String mimetype = aLine.substring(p + 1);

      // add mimetype
      List<String> values = mimeTypes.get(ext);
      if (values == null)
      {
         values = new ArrayList<String>();
         mimeTypes.put(ext, values);
      }
      values.add(mimetype);

      // add extension
      values = extentions.get(mimetype);
      if (values == null)
      {
         values = new ArrayList<String>();
         extentions.put(mimetype, values);
      }
      values.add(ext);
   }
}
