/*

 *   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.daemon.command;

import java.io.IOException;

import java.util.List;

import java.util.Locale;

import java.util.regex.PatternSyntaxException;

import org.sonews.daemon.NNTPConnection;

import org.sonews.storage.StorageBackendException;

import org.sonews.storage.StorageManager;

import org.sonews.util.Pair;

/**

 * <pre>

 *   XPAT header range|<message-id> pat [pat...]

 *

 *   The XPAT command is used to retrieve specific headers from

 *   specific articles, based on pattern matching on the contents of

 *   the header. This command was first available in INN.

 *

 *   The required header parameter is the name of a header line (e.g.

 *   "subject") in a news group article. See RFC-1036 for a list

 *   of valid header lines. The required range argument may be

 *   any of the following:

 *               an article number

 *               an article number followed by a dash to indicate

 *                  all following

 *               an article number followed by a dash followed by

 *                  another article number

 *

 *   The required message-id argument indicates a specific

 *   article. The range and message-id arguments are mutually

 *   exclusive. At least one pattern in wildmat must be specified

 *   as well. If there are additional arguments the are joined

 *   together separated by a single space to form one complete

 *   pattern. Successful responses start with a 221 response

 *   followed by a the headers from all messages in which the

 *   pattern matched the contents of the specified header line. This

 *   includes an empty list. Once the output is complete, a period

 *   is sent on a line by itself. If the optional argument is a

 *   message-id and no such article exists, the 430 error response

 *   is returned. A 502 response will be returned if the client only

 *   has permission to transfer articles.

 *

 *   Responses

 *

 *       221 Header follows

 *       430 no such article

 *       502 no permission

 *

 *   Response Data:

 *

 *       art_nr fitting_header_value

 * 

 * </pre>

 * [Source:"draft-ietf-nntp-imp-02.txt"] [Copyright: 1998 S. Barber]

 * 

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public class XPatCommand implements Command

{

  @Override

  public String[] getSupportedCommandStrings()

  {

    return new String[]{"XPAT"};

  }

  @Override

  public boolean hasFinished()

  {

    return true;

  }

  @Override

  public boolean isStateful()

  {

    return false;

  }

  @Override

  public void processLine(NNTPConnection conn, final String line, byte[] raw)

    throws IOException, StorageBackendException

  {

    if(conn.getCurrentChannel() == null)

    {

      conn.println("430 no group selected");

      return;

    }

    String[] command = line.split("\\p{Space}+");

    // There may be multiple patterns and Thunderbird produces

    // additional spaces between range and pattern

    if(command.length >= 4)

    {

      String header  = command[1].toLowerCase(Locale.US);

      String range   = command[2];

      String pattern = command[3];

      long start = -1;

      long end   = -1;

      if(range.contains("-"))

      {

        String[] rsplit = range.split("-", 2);

        start = Long.parseLong(rsplit[0]);

        if(rsplit[1].length() > 0)

        {

          end = Long.parseLong(rsplit[1]);

        }

      }

      else // TODO: Handle Message-IDs

      {

        start = Long.parseLong(range);

      }

      try

      {

        List<Pair<Long, String>> heads = StorageManager.current().

          getArticleHeaders(conn.getCurrentChannel(), start, end, header, pattern);

        conn.println("221 header follows");

        for(Pair<Long, String> head : heads)

        {

          conn.println(head.getA() + " " + head.getB());

        }

        conn.println(".");

      }

      catch(PatternSyntaxException ex)

      {

        ex.printStackTrace();

        conn.println("500 invalid pattern syntax");

      }

      catch(StorageBackendException ex)

      {

        ex.printStackTrace();

        conn.println("500 internal server error");

      }

    }

    else

    {

      conn.println("430 invalid command usage");

    }

  }

}