/*

 *   SONEWS News Server

 *   see AUTHORS for the list of contributors

 *

 *   This program is free software: you can redistribute it and/or modify

 *   it under the terms of the GNU General Public License as published by

 *   the Free Software Foundation, either version 3 of the License, or

 *   (at your option) any later version.

 *

 *   This program is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *   GNU General Public License for more details.

 *

 *   You should have received a copy of the GNU General Public License

 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

package org.sonews.util.io;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.UnsupportedEncodingException;

import java.net.Socket;

import java.net.UnknownHostException;

import org.sonews.config.Config;

import org.sonews.util.Log;

/**

 * Reads an news article from a NNTP server.

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public class ArticleReader 

{

  private BufferedOutputStream out;

  private BufferedInputStream  in;

  private String               messageID;

  public ArticleReader(String host, int port, String messageID)

    throws IOException, UnknownHostException

  {

    this.messageID = messageID;

    // Connect to NNTP server

    Socket socket = new Socket(host, port);

    this.out = new BufferedOutputStream(socket.getOutputStream());

    this.in  = new BufferedInputStream(socket.getInputStream());

    String line = readln(this.in);

    if(!line.startsWith("200 "))

    {

      throw new IOException("Invalid hello from server: " + line);

    }

  }

  private boolean eofArticle(byte[] buf)

  {

    if(buf.length < 4)

    {

      return false;

    }

    int l = buf.length - 1;

    return buf[l-3] == 10 // '*\n'

        && buf[l-2] == '.'                   // '.'

        && buf[l-1] == 13 && buf[l] == 10;  // '\r\n'

  }

  public byte[] getArticleData()

    throws IOException, UnsupportedEncodingException

  {

    long maxSize = Config.inst().get(Config.ARTICLE_MAXSIZE, 1024) * 1024L;

    try

    {

      this.out.write(("ARTICLE " + this.messageID + "\r\n").getBytes("UTF-8"));

      this.out.flush();

      String line = readln(this.in);

      if(line.startsWith("220 "))

      {

        ByteArrayOutputStream buf = new ByteArrayOutputStream();

        while(!eofArticle(buf.toByteArray()))

        {

          for(int b = in.read(); b != 10; b = in.read())

          {

            buf.write(b);

          }

          buf.write(10);

          if(buf.size() > maxSize)

          {

            Log.get().warning("Skipping message that is too large: " + buf.size());

            return null;

          }

        }

        return buf.toByteArray();

      }

      else

      {

        Log.get().warning("ArticleReader: " + line);

        return null;

      }

    }

    catch(IOException ex)

    {

      throw ex;

    }

    finally

    {

      this.out.write("QUIT\r\n".getBytes("UTF-8"));

      this.out.flush();

      this.out.close();

    }

  }

  private String readln(InputStream in)

    throws IOException

  {

    ByteArrayOutputStream buf = new ByteArrayOutputStream();

    for(int b = in.read(); b != 10 /* \n */; b = in.read())

    {

      buf.write(b);

    }

    return new String(buf.toByteArray());

  }

}