/****************************************************************
    * Licensed to the Apache Software Foundation (ASF) under one   *
    * or more contributor license agreements.  See the NOTICE file *
    * distributed with this work for additional information        *
    * regarding copyright ownership.  The ASF licenses this file   *
    * to you under the Apache License, Version 2.0 (the            *
    * "License"); you may not use this file except in compliance   *
    * with the License.  You may obtain a copy of the License at   *
    *                                                              *
   *   http://www.apache.org/licenses/LICENSE-2.0                 *
   *                                                              *
   * Unless required by applicable law or agreed to in writing,   *
   * software distributed under the License is distributed on an  *
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
   * KIND, either express or implied.  See the License for the    *
   * specific language governing permissions and limitations      *
   * under the License.                                           *
   ****************************************************************/
  
  package org.apache.james.user.impl.file;
  
  import java.io.BufferedInputStream;
  import java.io.BufferedOutputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.io.IOUtils;
  import org.apache.james.api.user.UserMetaDataRespository;
  import org.apache.james.api.user.UserRepositoryException;
  
  /**
   * Stores user meta-data in the file system.
   */
  public class FileUserMetaDataRepository implements UserMetaDataRespository {
      
      private static final String SERIALIZED_FILE_TYPE_NAME = ".ser";
  
      /** Characters that may safely be used to create names */
      private final static char[] SAFE_CHARS = {
          'a','b','c','d','e','f','g','h','i','j',
          'k','l','m','n','o','p','q','r','s','t',
          'u','v','w','x','y','z','0','1','2','3',
          '4','5','6','7','8','9'
      };
      
      private final String baseDirectory;
      
      public FileUserMetaDataRepository(final String baseDirectory) {
          super();
          this.baseDirectory = baseDirectory;
      }
  
      public void clear(String username) throws UserRepositoryException {
          final File userDir = userDirectory(username);
          try {
              FileUtils.deleteDirectory(userDir);
          } catch (IOException e) {
              throw new UserRepositoryException("Cannot delete " + userDir.getAbsolutePath(), e);
          }
      }
  
      public Serializable getAttribute(String username, String key)
              throws UserRepositoryException {
          final File valueFile = valueFile(username, key);
          final Serializable result;
          if (valueFile.exists()) {
              ObjectInputStream in = null;
              try {
                  in = new ObjectInputStream(new BufferedInputStream(new FileInputStream(valueFile)));
                  result = (Serializable) in.readObject();
              } catch (IOException e) {
                  throw new UserRepositoryException(e);
              } catch (ClassNotFoundException e) {
                  throw new UserRepositoryException(e);
              } finally {
                  IOUtils.closeQuietly(in);
              }
              
          } else {
              result = null;
          }
          return result;
      }
  
      public void setAttribute(String username, Serializable value, String key)
              throws UserRepositoryException {
  
          final File valueFile = valueFile(username, key);
          ObjectOutputStream out = null;
          try {
              
              out = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(valueFile)));
              out.writeObject(value);
             
         } catch (IOException e) {
             throw new UserRepositoryException(e);
         } finally {
             IOUtils.closeQuietly(out);
         }
     }
 
     private File valueFile(String username, String key) throws UserRepositoryException {
         final File userDir = userDirectory(username);
         
         final String valueFileName = fileSystemSafeName(key, SERIALIZED_FILE_TYPE_NAME);
         final File valueFile = new File(userDir, valueFileName);
         return valueFile;
     }
 
     private File userDirectory(String username) throws UserRepositoryException {
         final File baseDir = getBaseDirectory();
         
         final String userDirectoryName = fileSystemSafeName(username);
         final File userDir = new File(baseDir, userDirectoryName);
         if (!userDir.exists()) {
             if (!userDir.mkdir()) {
                 throw new UserRepositoryException("Cannot create directory: " + userDir.getAbsolutePath());
             }
         }
         return userDir;
     }
 
     private File getBaseDirectory() throws UserRepositoryException {
         final File baseDir = new File(baseDirectory);
         if (!baseDir.exists()) {
             if (!baseDir.mkdirs()) {
                 throw new UserRepositoryException("Cannot create directory: " + baseDirectory);
             }
         }
         return baseDir;
     }
 
     /**
      * Maps a value to a file-system safe name.
      * @param value name, not null
      * @param suffix optional suffix to be append, possibly null
      * @return file system safe mapping of the name
      */
     private String fileSystemSafeName(String value) {
         return fileSystemSafeName(value, null);
     }
     
     /**
      * Maps a value to a file-system safe name.
      * @param value name, not null
      * @param suffix optional suffix to be append, possibly null
      * @return file system safe mapping of the name
      */
     private String fileSystemSafeName(String value, String suffix) {
         final int length = value.length();
         final StringBuffer buffer = new StringBuffer(length * 10);
         for (int i=0;i<length;i++) {
             final int next = value.charAt(i);
             for (int j=0;j<4;j++) {
                 buffer.append(SAFE_CHARS[(next >> j * 4) % 32]);
             }
         }
         if (suffix != null) {
             buffer.append(suffix);
         }
         final String result = buffer.toString();
         return result;
     }
 }