/**
  UploadServer program - simple file upload web-server
  Author: Denis Volkov (c) 2007
  For information and support visit http://www.denvo.ru

  This program is FREEWARE, you are free to use any part of code
  as well as whole program in your development provided that you
  remain original copyrights and site name in your source.

  The product is distributed "as is". The author of the Product will
  not be liable for any consequences, loss of profit or any other kind
  of loss, that may occur while using the product itself and/or together
  with any other software.
*/

import java.net.*;
import java.io.*;
import java.security.*;
import java.util.*;
import java.util.regex.*;
import java.nio.charset.*;

public class UploadServer extends Thread
{
  private final static String httpHeader = "HTTP/1.1 200 OK\r\n"
    + "Content-Type: text/html\r\n"
    + "\r\n";
  private final static String uploadFormString = httpHeader
    + "<form method=\"POST\" enctype=\"multipart/form-data\">\r\n"
    + "<input type=\"file\" name=\"upload_file\" size=100>\r\n"
    + "<input type=\"submit\" value=\"Upload\">\r\n"
    + "</form>\r\n\r\n";

  private final Charset streamCharset = Charset.forName("ISO-8859-1");

  private ServerSocket serverSocket;
  private Socket clientSocket;

  UploadServer(int port) throws Exception
  {
    serverSocket = new ServerSocket(port);
    System.err.println("Server ready @" + port);
  }

  public void run()
  {
    while(true)
    {
      try
      {
        clientSocket = serverSocket.accept();
        System.err.println("Client connection accepted from "
          + clientSocket.getInetAddress().toString());
        // Read and process data from socket
        processConnection();
      }
      catch(Exception e)
      {
        System.err.println("Exception in run's main loop");
        e.printStackTrace();
      }
      // Close socket
      try
      {
        clientSocket.close();
      }
      catch(Exception e) { }
      System.err.println("Client connection closed");
    }
  }

  private void processConnection() throws Exception
  {
    InputStream inStream = clientSocket.getInputStream();
    BufferedReader in = new BufferedReader(new InputStreamReader(inStream, streamCharset));
    OutputStream out = clientSocket.getOutputStream();
    // Read requiest header
    String headerLine, firstLine = null;
    Map headerData = new TreeMap();
    Pattern headerPattern = Pattern.compile("([^\\:]+)\\:(.*)");
    while((headerLine = in.readLine()).length() > 0)
    {
      if(firstLine == null)
        firstLine = headerLine;
      else
      {
        Matcher m = headerPattern.matcher(headerLine);
        if(m.matches())
        {
          headerData.put(m.group(1).trim(), m.group(2).trim());
        }
      }
      System.out.println("HEADER: " + headerLine);
    }
    // Process first line of request
    if(firstLine.startsWith("GET"))
    {
      System.out.println("Send upload form");
      // Show upload form
      out.write(uploadFormString.getBytes());
    }
    else if(firstLine.startsWith("POST"))
    {
      // Get body info
      int contentLength = Integer.parseInt((String)(headerData.get("Content-Length")));
      String contentType = (String)(headerData.get("Content-Type"));
      String boundary = "\r\n--" + contentType.substring(contentType.indexOf("boundary=") + 9) + "--";
      System.out.println("File upload, reading body: " + contentLength + " bytes");
      // Prepare to reading
      Pattern fileNamePattern = Pattern.compile("filename=\"([^\"]+)\"");
      OutputStreamWriter writer = null;
      MessageDigest digestMD5 = MessageDigest.getInstance("MD5");
      String fileName = null;
      String prevBuffer = "";
      char[] buffer = new char[16 << 10];
      int totalLength = contentLength;
      // Reading loop
      while(contentLength > 0)
      {
        if(writer == null)
        {
          // Read strings
          String bodyLine = in.readLine();
          contentLength -= bodyLine.length() + 2;
          // Find name of file
          if(bodyLine.length() > 0)
          {
            Matcher m = fileNamePattern.matcher(bodyLine);
            if(m.find())
            {
              fileName = m.group(1);
            }
          }
          else if(fileName != null)
          {
            OutputStream stream = new FileOutputStream(fileName);
            if(digestMD5 != null)
              stream = new DigestOutputStream(stream, digestMD5);
            writer = new OutputStreamWriter(stream, streamCharset);
          }
          else
            throw new RuntimeException("Name of uploaded file not found");
        }
        else
        {
          // Read data from stream
          int readLength = Math.min(contentLength, buffer.length);
          readLength = in.read(buffer, 0, readLength);
          if(readLength < 0)
            break;
          contentLength -= readLength;
          // Find boundary string
          String curBuffer = new String(buffer, 0, readLength);
          String bothBuffers = prevBuffer + curBuffer;
          int boundaryPos = bothBuffers.indexOf(boundary);
          if(boundaryPos == -1)
          {
            writer.write(prevBuffer, 0, prevBuffer.length());
            prevBuffer = curBuffer;
          }
          else
          {
            writer.write(bothBuffers, 0, boundaryPos);
            break;
          }
        }
        // Write stats
        System.out.print("Read: " + (totalLength - contentLength)
          + " Remains: " + contentLength + " Total: " + totalLength
          + " bytes       \r");
      }
      System.out.println("Done                                                 ");
      writer.close();
      // Finalize digest calculation
      byte[] md5Sum = digestMD5.digest();
      StringBuffer md5SumString = new StringBuffer();
      for(int n = 0; n < md5Sum.length; ++ n)
        md5SumString.append(printByte(md5Sum[n]));
      // Output client info
      String answer = httpHeader + "<p><b>Upload completed, " + totalLength
        + " bytes, MD5 sum: " + md5SumString.toString() + "</b>"
        + "<p><a href=\"/\">Next file</a>\r\n\r\n";
      out.write(answer.getBytes());
    }
  }

  private static String printByte(byte b)
  {
    int bi = ((int)b) & 0xFF;
    if(bi < 16)
      return "0" + Integer.toHexString(bi);
    else
      return Integer.toHexString(bi);
  }

  public static void main(String[] args)
  {
    try
    {
      if(args.length < 1)
      {
        System.out.println("Usage: UploadServer <port>");
        return;
      }
      UploadServer server = new UploadServer(Integer.parseInt(args[0]));
      server.start();
    }
    catch(Exception e)
    {
      System.err.println("Error in main");
      e.printStackTrace();
    }
  }
}