/*

  * Copyright 2008 the original author or authors.

  *

  * Licensed 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.mockftpserver.fake.command;

 import org.mockftpserver.core.command.Command;

 import org.mockftpserver.core.command.ReplyCodes;

 import org.mockftpserver.core.session.Session;

 import org.mockftpserver.core.session.SessionKeys;

 import org.mockftpserver.core.util.IoUtil;

 import org.mockftpserver.fake.filesystem.FileEntry;

 import org.mockftpserver.fake.filesystem.FileSystemEntry;

 import org.mockftpserver.fake.filesystem.FileSystemException;

 import java.io.ByteArrayOutputStream;

 import java.io.IOException;

 import java.io.InputStream;

 /**

  * CommandHandler for the RETR command. Handler logic:

  * <ol>

  * <li>If the user has not logged in, then reply with 530 and terminate</li>

  * <li>If the required pathname parameter is missing, then reply with 501 and terminate</li>

  * <li>If the pathname parameter does not specify a valid, existing filename, then reply with 550 and terminate</li>

  * <li>If the current user does not have read access to the file at the specified path or execute permission to its directory, then reply with 550 and terminate</li>

  * <li>Send an initial reply of 150</li>

  * <li>Send the contents of the named file across the data connection</li>

  * <li>If there is an error reading the file, then reply with 550 and terminate</li>

  * <li>Send a final reply with 226</li>

  * </ol>

  *

  * @author Chris Mair

  * @version $Revision: 214 $ - $Date: 2008-12-26 20:00:19 -0500 (Fri, 26 Dec 2008) $

  */

 public class RetrCommandHandler extends AbstractFakeCommandHandler {

     protected void handle(Command command, Session session) {

         verifyLoggedIn(session);

         this.replyCodeForFileSystemException = ReplyCodes.READ_FILE_ERROR;

         String path = getRealPath(session, command.getRequiredParameter(0));

         FileSystemEntry entry = getFileSystem().getEntry(path);

         verifyFileSystemCondition(entry != null, path, "filesystem.doesNotExist");

         verifyFileSystemCondition(!entry.isDirectory(), path, "filesystem.isNotAFile");

         FileEntry fileEntry = (FileEntry) entry;

         // User must have read permission to the file

         verifyReadPermission(session, path);

         // User must have execute permission to the parent directory

         verifyExecutePermission(session, getFileSystem().getParent(path));

         sendReply(session, ReplyCodes.TRANSFER_DATA_INITIAL_OK);

         InputStream input = fileEntry.createInputStream();

         session.openDataConnection();

         byte[] bytes = null;

         try {

             bytes = IoUtil.readBytes(input);

         }

         catch (IOException e) {

             LOG.error("Error reading from file [" + fileEntry.getPath() + "]", e);

             throw new FileSystemException(fileEntry.getPath(), null, e);

         }

         finally {

             try {

                 input.close();

             }

             catch (IOException e) {

                 LOG.error("Error closing InputStream for file [" + fileEntry.getPath() + "]", e);

             }

         }

         if (isAsciiMode(session)) {

             bytes = convertLfToCrLf(bytes);

         }

         session.sendData(bytes, bytes.length);

         session.closeDataConnection();

         sendReply(session, ReplyCodes.TRANSFER_DATA_FINAL_OK);

     }

     /**

      * Within the specified byte array, replace all LF (\n) that are NOT preceded by a CR (\r) into CRLF (\r\n).

      *

      * @param bytes - the bytes to be converted

      * @return the result of converting LF to CRLF

      */

     protected byte[] convertLfToCrLf(byte[] bytes) {

         ByteArrayOutputStream out = new ByteArrayOutputStream();

         char lastChar = ' ';

         for (int i = 0; i < bytes.length; i++) {

             char ch = (char) bytes[i];

             if (ch == '\n' && lastChar != '\r') {

                 out.write('\r');

                 out.write('\n');

             } else {

                 out.write(bytes[i]);

             }

             lastChar = ch;

         }

         return out.toByteArray();

     }

     private boolean isAsciiMode(Session session) {

         // Defaults to true

         return session.getAttribute(SessionKeys.ASCII_TYPE) != Boolean.FALSE;

     }

 }