/*
 * Copyright (C) The Apache Software Foundation. All rights reserved.
 *
 * This software is published under the terms of the Apache Software License
 * version 1.1, a copy of which has been included with this distribution in
 * the LICENSE file.
 */
package server.ftp;

import io.IoUtils;
import io.StreamConnector;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.RandomAccessFile;
import java.io.Writer;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.StringTokenizer;

/**
 * This class handles each ftp connection. Here all the ftp command
 * methods take two arguments - a ftp request and a writer object. 
 * This is the main backbone of the ftp server.
 * <br>
 * The ftp command method signature is: 
 * <code>public void doXYZ(FtpRequest request, FtpWriter out) throws IOException</code>.
 * <br>
 * Here <code>XYZ</code> is the capitalized ftp command. 
 *
 * @author <a href="mailto:rana_b@yahoo.com">Rana Bhattacharyya</a>
 */
public
class FtpConnection extends BaseFtpConnection {
        
    // as SimpleDateFormat is not thread-safe we have to use ThreadLocal
    private final static ThreadLocal DATE_FMT = new ThreadLocal() {
        protected Object initialValue() {
            return new SimpleDateFormat("yyyyMMddHHmmss.SSS"); 
        }
    };
    
    // command state specific temporary variables
    private boolean mbReset   = false;
    private long    mlSkipLen = 0;     
    
    private boolean mbRenFr   = false;
    private String  mstRenFr  = null;
    
    private boolean mbUser    = false;
    private boolean mbPass    = false;
    
    /**
     * Set configuration file and the control socket. 
     */
    public FtpConnection(FtpConfig cfg, Socket soc) {
        super(cfg, soc);
    }
     
    /**
     * Check the user permission to execute this command.
     */
    protected boolean hasPermission(FtpRequest request) {
        String cmd = request.getCommand();
        return mUser.hasLoggedIn() || 
                cmd.equals("USER") || 
                cmd.equals("PASS") ||
                cmd.equals("HELP") ||
                cmd.equals("SYST");
    }
     
    /**
     * Reset temporary state variables.
     */
    private void resetState() {
        mbRenFr = false;
        mstRenFr = null;
            
        mbReset = false;
        mlSkipLen = 0;
            
        mbUser = false;
        mbPass = false;
    }
 
     ////////////////////////////////////////////////////////////
     /////////////////   all the FTP handlers   /////////////////
     ////////////////////////////////////////////////////////////
     /**
      * <code>ABOR &lt;CRLF&gt;</code><br>
      *
      * This command tells the server to abort the previous FTP
      * service command and any associated transfer of data.
      * No action is to be taken if the previous command
      * has been completed (including data transfer).  The control
      * connection is not to be closed by the server, but the data
      * connection must be closed.  
      * Current implementation does not do anything. As here data 
      * transfers are not multi-threaded. 
      */
     public void doABOR(FtpRequest request, FtpWriter out) throws IOException {
         
         // reset state variables
         resetState();
         
         // and abort any data connection
         mDataConnection.closeDataSocket();
         out.write(mFtpStatus.getResponse(226, request, mUser, null));
     }
     
     
     /**
      * <code>APPE &lt;SP&gt; &lt;pathname&gt; &lt;CRLF&gt;</code><br>
      *
      * This command causes the server-DTP to accept the data
      * transferred via the data connection and to store the data in
      * a file at the server site.  If the file specified in the
      * pathname exists at the server site, then the data shall be
      * appended to that file; otherwise the file specified in the
      * pathname shall be created at the server site.
      */
     public void doAPPE(FtpRequest request, FtpWriter out) throws IOException {
         
         InputStream is = null;
         OutputStream os = null;
         String[] args = null;
         
         try {           
         
             // reset state variables
             resetState();
             
             // argument check
             if(!request.hasArgument()) {
                out.write(mFtpStatus.getResponse(501, request, mUser, null));
                return;  
             }
             
             // get filenames
             String fileName = request.getArgument();
             fileName = mUser.getVirtualDirectory().getAbsoluteName(fileName);
             String physicalName = mUser.getVirtualDirectory().getPhysicalName(fileName);
             File requestedFile = new File(physicalName);
             args = new String[] {fileName};
             
             // check file existance
             if( !(requestedFile.exists() && requestedFile.isFile()) ) {
                 out.write(mFtpStatus.getResponse(550, request, mUser, args));
                 return;
             }
             
             // check permission
             if(!mUser.getVirtualDirectory().hasWritePermission(physicalName, true)) {
                 out.write(mFtpStatus.getResponse(450, request, mUser, args));
                 return;
             }
             
             // now transfer file data
             out.write(mFtpStatus.getResponse(150, request, mUser, args));
             Socket dataSoc = mDataConnection.getDataSocket();
             if (dataSoc == null) {
                  out.write(mFtpStatus.getResponse(550, request, mUser, args));
                  return;
             }
             
             // go to the end of the file
             is = dataSoc.getInputStream();
             RandomAccessFile raf = new RandomAccessFile(requestedFile, "rw");
             raf.seek(raf.length());
             os = mUser.getOutputStream( new FileOutputStream(raf.getFD()) );
             
             // receive data from client
             StreamConnector msc = new StreamConnector(is, os);
             msc.setMaxTransferRate(mUser.getMaxUploadRate());
             msc.setObserver(this);
             msc.connect();
             
             if(msc.hasException()) {
                 out.write(mFtpStatus.getResponse(451, request, mUser, args));
             }
             else {
                 mConfig.getStatistics().setUpload(requestedFile, mUser, msc.getTransferredSize());
             }
             
             out.write(mFtpStatus.getResponse(226, request, mUser, args));
         }
         catch(IOException ex) {
             out.write(mFtpStatus.getResponse(425, request, mUser, args));
         }
         finally {
            IoUtils.close(is);
            IoUtils.close(os);
            mDataConnection.closeDataSocket(); 
         }
     }
     
     
     /**
      * <code>CDUP &lt;CRLF&gt;</code><br>
      *
      * This command is a special case of CWD, and is included to
      * simplify the implementation of programs for transferring
      * directory trees between operating systems having different
      * syntaxes for naming the parent directory.  The reply codes
      * shall be identical to the reply codes of CWD.      
      */
     public void doCDUP(FtpRequest request, FtpWriter out) throws IOException {
         
         // reset state variables
         resetState();
         
         // change directory
         if (mUser.getVirtualDirectory().changeDirectory("..")) {
             String args[] = {mUser.getVirtualDirectory().getCurrentDirectory()};
             out.write(mFtpStatus.getResponse(200, request, mUser, args));
         }
         else {
             out.write(mFtpStatus.getResponse(431, request, mUser, null));
         }
     }
     
     
     /**
      * <code>CWD  &lt;SP&gt; &lt;pathname&gt; &lt;CRLF&gt;</code><br>
      *
      * This command allows the user to work with a different
      * directory for file storage or retrieval without
      * altering his login or accounting information.  Transfer
      * parameters are similarly unchanged.  The argument is a
      * pathname specifying a directory.
      */
     public void doCWD(FtpRequest request, FtpWriter out) throws IOException {
         
         // reset state variables
         resetState();
         
         // get new directory name
         String dirName = "/";
         if (request.hasArgument()) {
             dirName = request.getArgument();
         } 
         
         // change directory
         if (mUser.getVirtualDirectory().changeDirectory(dirName)) {
             String args[] = {mUser.getVirtualDirectory().getCurrentDirectory()};
             out.write(mFtpStatus.getResponse(200, request, mUser, args));
         }
         else {
             out.write(mFtpStatus.getResponse(431, request, mUser, null));
         }
     }
     
     
     /**
      * <code>DELE &lt;SP&gt; &lt;pathname&gt; &lt;CRLF&gt;</code><br>
      *
      * This command causes the file specified in the pathname to be
      * deleted at the server site.
      */
     public void doDELE(FtpRequest request, FtpWriter out) throws IOException {
        
        // reset state variables
        resetState();  
         
        // argument check
        if(!request.hasArgument()) {
           out.write(mFtpStatus.getResponse(501, request, mUser, null));
           return;  
        }    
        
        // get filenames
        String fileName = request.getArgument();
        fileName = mUser.getVirtualDirectory().getAbsoluteName(fileName);
        String physicalName = mUser.getVirtualDirectory().getPhysicalName(fileName);
        File requestedFile = new File(physicalName);
        String[] args = {fileName};
        
        // check permission
        if(!mUser.getVirtualDirectory().hasWritePermission(physicalName, true)) {
            out.write(mFtpStatus.getResponse(450, request, mUser, args));
            return;
        }
        
        // now delete
        if(requestedFile.delete()) {
           out.write(mFtpStatus.getResponse(250, request, mUser, args)); 
           mConfig.getStatistics().setDelete(requestedFile, mUser); 
        }
        else {
           out.write(mFtpStatus.getResponse(450, request, mUser, args));
        }
     }
     
     
     /**
      * <code>HELP [&lt;SP&gt; <string>] &lt;CRLF&gt;</code><br>
      *
      * This command shall cause the server to send helpful
      * information regarding its implementation status over the
      * control connection to the user.  The command may take an
      * argument (e.g., any command name) and return more specific
      * information as a response.
      */
     public void doHELP(FtpRequest request, FtpWriter out) throws IOException {
         resetState();
         
         // print global help
         if(!request.hasArgument()) {
             out.write(mFtpStatus.getResponse(214, null, mUser, null));
             return;
         }
         
         // print command specific help
         String ftpCmd = request.getArgument().toUpperCase();
         String args[] = null;
         FtpRequest tempRequest = new FtpRequest(ftpCmd);