/*
    * 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.commons.vfs2.impl;
  
  import java.io.File;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  import java.security.PrivilegedActionException;
  import java.security.PrivilegedExceptionAction;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.vfs2.FileObject;
  import org.apache.commons.vfs2.FileSelector;
  import org.apache.commons.vfs2.FileSystemException;
  import org.apache.commons.vfs2.provider.FileReplicator;
  import org.apache.commons.vfs2.provider.VfsComponent;
  import org.apache.commons.vfs2.provider.VfsComponentContext;
  
  /**
   * A file replicator that wraps another file replicator, performing the replication as a privileged action.
   */
  public class PrivilegedFileReplicator implements FileReplicator, VfsComponent {
  
      private final FileReplicator replicator;
      private final VfsComponent replicatorComponent;
  
      public PrivilegedFileReplicator(final FileReplicator replicator) {
          this.replicator = replicator;
          if (replicator instanceof VfsComponent) {
              replicatorComponent = (VfsComponent) replicator;
          } else {
              replicatorComponent = null;
          }
      }
  
      /**
       * Sets the Logger to use for the component.
       *
       * @param logger The logger.
       */
      @Override
      public void setLogger(final Log logger) {
          if (replicatorComponent != null) {
              replicatorComponent.setLogger(logger);
          }
      }
  
      /**
       * Sets the context for the replicator.
       *
       * @param context The component context.
       */
      @Override
      public void setContext(final VfsComponentContext context) {
          if (replicatorComponent != null) {
              replicatorComponent.setContext(context);
          }
      }
  
      /**
       * Initializes the component.
       *
       * @throws FileSystemException if an error occurs.
       */
      @Override
      public void init() throws FileSystemException {
          if (replicatorComponent != null) {
              try {
                  AccessController.doPrivileged(new InitAction());
              } catch (final PrivilegedActionException e) {
                  throw new FileSystemException("vfs.impl/init-replicator.error", e);
              }
          }
      }
  
      /**
       * Closes the replicator.
       */
      @Override
      public void close() {
          if (replicatorComponent != null) {
              AccessController.doPrivileged(new CloseAction());
          }
      }
  
     /**
      * Creates a local copy of the file, and all its descendants.
      *
      * @param srcFile The source FileObject.
      * @param selector The file selector.
      * @return The replicated file.
      * @throws FileSystemException if an error occurs.
      */
     @Override
     public File replicateFile(final FileObject srcFile, final FileSelector selector) throws FileSystemException {
         try {
             final ReplicateAction action = new ReplicateAction(srcFile, selector);
             return AccessController.doPrivileged(action);
         } catch (final PrivilegedActionException e) {
             throw new FileSystemException("vfs.impl/replicate-file.error", e, srcFile.getName());
         }
     }
 
     /**
      * An action that initializes the wrapped replicator.
      */
     private class InitAction implements PrivilegedExceptionAction<Object> {
         /**
          * Performs the action.
          */
         @Override
         public Object run() throws Exception {
             replicatorComponent.init();
             return null;
         }
     }
 
     /**
      * An action that replicates a file using the wrapped replicator.
      */
     private class ReplicateAction implements PrivilegedExceptionAction<File> {
         private final FileObject srcFile;
         private final FileSelector selector;
 
         public ReplicateAction(final FileObject srcFile, final FileSelector selector) {
             this.srcFile = srcFile;
             this.selector = selector;
         }
 
         /**
          * Performs the action.
          *
          * @throws Exception if an error occurs.
          */
         @Override
         public File run() throws Exception {
             // TODO - Do not pass the selector through. It is untrusted
             // TODO - Need to determine which files can be read
             return replicator.replicateFile(srcFile, selector);
         }
     }
 
     /**
      * An action that closes the wrapped replicator.
      */
     private class CloseAction implements PrivilegedAction<Object> {
         /**
          * Performs the action.
          */
         @Override
         public Object run() {
             replicatorComponent.close();
             return null;
         }
     }
 }