/*
    * 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.provider.ftp;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.time.Instant;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.commons.net.ftp.FTPClient;
  import org.apache.commons.net.ftp.FTPConnectionClosedException;
  import org.apache.commons.net.ftp.FTPFile;
  import org.apache.commons.net.ftp.FTPReply;
  import org.apache.commons.vfs2.FileSystemException;
  import org.apache.commons.vfs2.FileSystemOptions;
  import org.apache.commons.vfs2.UserAuthenticationData;
  import org.apache.commons.vfs2.provider.GenericFileName;
  import org.apache.commons.vfs2.util.UserAuthenticatorUtils;
  
  /**
   * A wrapper to the FTPClient to allow automatic reconnect on connection loss.
   * <p>
   * I decided to not to use eg. noop() to determine the state of the connection to avoid unnecessary server round-trips.
   * </p>
   */
  public class FTPClientWrapper implements FtpClient {
  
      private static final Log LOG = LogFactory.getLog(FTPClientWrapper.class);
  
      /**
       * Authentication options.
       */
      protected final FileSystemOptions fileSystemOptions;
      private FTPClient ftpClient;
      private final GenericFileName rootFileName;
  
      /**
       * Constructs a new instance.
       *
       * @param rootFileName the root file name.
       * @param fileSystemOptions the file system options.
       * @throws FileSystemException if a file system error occurs.
       */
      protected FTPClientWrapper(final GenericFileName rootFileName, final FileSystemOptions fileSystemOptions)
          throws FileSystemException {
          this.rootFileName = rootFileName;
          this.fileSystemOptions = fileSystemOptions;
          getFtpClient(); // fail-fast
      }
  
      @Override
      public boolean abort() throws IOException {
          try {
              // imario@apache.org: 2005-02-14
              // it should be better to really "abort" the transfer, but
              // currently I didn't manage to make it work - so lets "abort" the hard way.
              // return getFtpClient().abort();
              disconnect();
              return true;
          } catch (final IOException e) {
              disconnect();
          }
          return true;
      }
  
      @Override
      public OutputStream appendFileStream(final String relPath) throws IOException {
          try {
              return getFtpClient().appendFileStream(relPath);
          } catch (final IOException e) {
              disconnect();
              return getFtpClient().appendFileStream(relPath);
          }
      }
  
      @Override
      public boolean completePendingCommand() throws IOException {
          if (ftpClient != null) {
              return getFtpClient().completePendingCommand();
          }
          return true;
      }
  
     /**
      * Creates an FTP client.
      *
      * @return a new FTP client.
      * @throws FileSystemException if an error occurs while establishing a connection.
      */
     private FTPClient createClient() throws FileSystemException {
         final GenericFileName rootName = getRoot();
         UserAuthenticationData authData = null;
         try {
             authData = UserAuthenticatorUtils.authenticate(fileSystemOptions, FtpFileProvider.AUTHENTICATOR_TYPES);
             return createClient(rootName, authData);
         } finally {
             UserAuthenticatorUtils.cleanup(authData);
         }
     }
 
     /**
      * Creates an FTPClient.
      *
      * @param rootFileName the root file name.
      * @param authData authentication data.
      * @return an FTPClient.
      * @throws FileSystemException if an error occurs while establishing a connection.
      */
     protected FTPClient createClient(final GenericFileName rootFileName, final UserAuthenticationData authData)
         throws FileSystemException {
         return FtpClientFactory.createConnection(rootFileName.getHostName(), rootFileName.getPort(),
             UserAuthenticatorUtils.getData(authData, UserAuthenticationData.USERNAME,
                 UserAuthenticatorUtils.toChar(rootFileName.getUserName())),
             UserAuthenticatorUtils.getData(authData, UserAuthenticationData.PASSWORD,
                 UserAuthenticatorUtils.toChar(rootFileName.getPassword())),
             rootFileName.getPath(), getFileSystemOptions());
     }
 
     @Override
     public boolean deleteFile(final String relPath) throws IOException {
         try {
             return getFtpClient().deleteFile(relPath);
         } catch (final IOException e) {
             disconnect();
             return getFtpClient().deleteFile(relPath);
         }
     }
 
     @Override
     public void disconnect() throws IOException {
         if (ftpClient != null) {
             try {
                 ftpClient.quit();
             } catch (final IOException e) {
                 LOG.debug("I/O exception while trying to quit, connection likely timed out, ignoring.", e);
             } finally {
                 try {
                     getFtpClient().disconnect();
                 } catch (final IOException e) {
                     LOG.warn("I/O exception while trying to disconnect, connection likely closed, ignoring.", e);
                 } finally {
                     ftpClient = null;
                 }
             }
         }
     }
 
     /**
      * Gets the FileSystemOptions.
      *
      * @return the FileSystemOptions.
      */
     public FileSystemOptions getFileSystemOptions() {
         return fileSystemOptions;
     }
 
     /**
      * Package-private for debugging only, consider private.
      *
      * @return the actual FTP client.
      * @throws FileSystemException if an error occurs while establishing a connection.
      */
     FTPClient getFtpClient() throws FileSystemException {
         if (ftpClient == null) {
             ftpClient = createClient();
         }
         return ftpClient;
     }
 
     @Override
     public int getReplyCode() throws IOException {
         return getFtpClient().getReplyCode();
     }
 
     @Override
     public String getReplyString() throws IOException {
         return getFtpClient().getReplyString();
     }
 
     /**
      * Gets the root file name.
      *
      * @return  the root file name.
      */
     public GenericFileName getRoot() {
         return rootFileName;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean hasFeature(final String feature) throws IOException {
         try {
             return getFtpClient().hasFeature(feature);
         } catch (final IOException ex) {
             disconnect();
             return getFtpClient().hasFeature(feature);
         }
     }
 
     @Override
     public boolean isConnected() throws FileSystemException {
         return ftpClient != null && ftpClient.isConnected();
     }
 
     @Override
     public FTPFile[] listFiles(final String relPath) throws IOException {
         try {
             // VFS-210: return getFtpClient().listFiles(relPath);
             return listFilesInDirectory(relPath);
         } catch (final IOException e) {
             disconnect();
             return listFilesInDirectory(relPath);
         }
     }
 
     private FTPFile[] listFilesInDirectory(final String relPath) throws IOException {
         // VFS-307: no check if we can simply list the files, this might fail if there are spaces in the path
         FTPFile[] ftpFiles = getFtpClient().listFiles(relPath);
         if (FTPReply.isPositiveCompletion(getFtpClient().getReplyCode())) {
             return ftpFiles;
         }
 
         // VFS-307: now try the hard way by cd'ing into the directory, list and cd back
         // if VFS is required to fallback here the user might experience a real bad FTP performance
         // as then every list requires 4 FTP commands.
         String workingDirectory = null;
         if (relPath != null) {
             workingDirectory = getFtpClient().printWorkingDirectory();
             if (!getFtpClient().changeWorkingDirectory(relPath)) {
                 return null;
             }
         }
 
         ftpFiles = getFtpClient().listFiles();
 
         if (relPath != null && !getFtpClient().changeWorkingDirectory(workingDirectory)) {
             throw new FileSystemException("vfs.provider.ftp.wrapper/change-work-directory-back.error",
                 workingDirectory);
         }
         return ftpFiles;
     }
 
     @Override
     public boolean makeDirectory(final String relPath) throws IOException {
         try {
             return getFtpClient().makeDirectory(relPath);
         } catch (final IOException e) {
             disconnect();
             return getFtpClient().makeDirectory(relPath);
         }
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Instant mdtmInstant(final String relPath) throws IOException {
         try {
             return getFtpClient().mdtmCalendar(relPath).toInstant();
         } catch (final IOException ex) {
             disconnect();
             return getFtpClient().mdtmCalendar(relPath).toInstant();
         }
     }
 
     @Override
     public boolean removeDirectory(final String relPath) throws IOException {
         try {
             return getFtpClient().removeDirectory(relPath);
         } catch (final IOException e) {
             disconnect();
             return getFtpClient().removeDirectory(relPath);
         }
     }
 
     @Override
     public boolean rename(final String oldName, final String newName) throws IOException {
         try {
             return getFtpClient().rename(oldName, newName);
         } catch (final IOException e) {
             disconnect();
             return getFtpClient().rename(oldName, newName);
         }
     }
 
     @Override
     public InputStream retrieveFileStream(final String relPath) throws IOException {
         try {
             return getFtpClient().retrieveFileStream(relPath);
         } catch (final IOException e) {
             disconnect();
             return getFtpClient().retrieveFileStream(relPath);
         }
     }
 
     @Override
     public InputStream retrieveFileStream(final String relPath, final int bufferSize) throws IOException {
         try {
             final FTPClient client = getFtpClient();
             client.setBufferSize(bufferSize);
             return client.retrieveFileStream(relPath);
         } catch (final IOException e) {
             disconnect();
             final FTPClient client = getFtpClient();
             client.setBufferSize(bufferSize);
             return client.retrieveFileStream(relPath);
         }
     }
 
     @Override
     public InputStream retrieveFileStream(final String relPath, final long restartOffset) throws IOException {
         try {
             final FTPClient client = getFtpClient();
             client.setRestartOffset(restartOffset);
             return client.retrieveFileStream(relPath);
         } catch (final IOException e) {
             disconnect();
             final FTPClient client = getFtpClient();
             client.setRestartOffset(restartOffset);
             return client.retrieveFileStream(relPath);
         }
     }
 
     /**
      * A convenience method to send the FTP OPTS command to the server, receive the reply, and return the reply code.
      * <p>
      * FTP request Syntax:
      * </p>
      * <pre>{@code
      * opts             = opts-cmd SP command-name
      *                         [ SP command-options ] CRLF
      * opts-cmd         = "opts"
      * command-name     = <any FTP command which allows option setting>
      * command-options  = <format specified by individual FTP command>
      * }</pre>
      * @param commandName The OPTS command name.
      * @param commandOptions The OPTS command options.
      * @return The reply code received from the server.
      * @throws FTPConnectionClosedException If the FTP server prematurely closes the connection as a result of the client being idle or some other reason
      *                                      causing the server to send FTP reply code 421. This exception may be caught either as an IOException or
      *                                      independently as itself.
      * @throws IOException                  If an I/O error occurs while either sending the command or receiving the server reply.
      * @since 2.11.0
      */
     public int sendOptions(final String commandName, String commandOptions) throws IOException {
         // Commons Net 3.12.0
         // return getFtpClient().opts(commandName, commandOptions);
         return getFtpClient().sendCommand("OPTS", commandName + ' ' + commandOptions);
     }
 
     @Override
     public void setBufferSize(final int bufferSize) throws FileSystemException {
         getFtpClient().setBufferSize(bufferSize);
     }
 
     @Override
     public OutputStream storeFileStream(final String relPath) throws IOException {
         try {
             return getFtpClient().storeFileStream(relPath);
         } catch (final IOException e) {
             disconnect();
             return getFtpClient().storeFileStream(relPath);
         }
     }
 }