/*

 *   StarOffice 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 com.so.news.command;

import java.text.SimpleDateFormat;

import java.util.Locale;

import com.so.news.Debug;

import com.so.news.NNTPConnection;

import com.so.news.storage.Article;

/**

 * Class handling the OVER/XOVER command.

 * 

 * Description of the XOVER command:

 * 

 * XOVER [range]

 *

 * The XOVER command returns information from the overview

 * database for the article(s) specified.

 *

 * The optional 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

 *

 * If no argument is specified, then information from the

 * current article is displayed. Successful responses start

 * with a 224 response followed by the overview information

 * for all matched messages. Once the output is complete, a

 * period is sent on a line by itself. If no argument is

 * specified, the information for the current article is

 * returned.  A news group must have been selected earlier,

 * else a 412 error response is returned. If no articles are

 * in the range specified, a 420 error response is returned

 * by the server. A 502 response will be returned if the

 * client only has permission to transfer articles.

 *

 * Each line of output will be formatted with the article number,

 * followed by each of the headers in the overview database or the

 * article itself (when the data is not available in the overview

 * database) for that article separated by a tab character.  The

 * sequence of fields must be in this order: subject, author,

 * date, message-id, references, byte count, and line count. Other

 * optional fields may follow line count. Other optional fields may

 * follow line count. These fields are specified by examining the

 * response to the LIST OVERVIEW.FMT command. Where no data exists,

 * a null field must be provided (i.e. the output will have two tab

 * characters adjacent to each other). Servers should not output

 * fields for articles that have been removed since the XOVER database

 * was created.

 *

 * The LIST OVERVIEW.FMT command should be implemented if XOVER

 * is implemented. A client can use LIST OVERVIEW.FMT to determine

 * what optional fields  and in which order all fields will be

 * supplied by the XOVER command. 

 *

 * Note that any tab and end-of-line characters in any header

 * data that is returned will be converted to a space character.

 *

 * Responses:

 *

 *   224 Overview information follows

 *   412 No news group current selected

 *   420 No article(s) selected

 *   502 no permission

 * 

 * @author Christian Lins

 */

public class OverCommand extends Command

{

  public OverCommand(NNTPConnection conn)

  {

    super(conn);

  }

  public boolean process(String[] command)

    throws Exception

  {

    if(getCurrentGroup() == null)

    {

      printStatus(412, "No news group current selected");

      return false;

    }

    // If no parameter was specified, show information about

    // the currently selected article(s)

    if(command.length == 1)

    {

      Article art = getCurrentArticle();

      if(art == null)

      {

        printStatus(420, "No article(s) selected");

        return false;

      }

      String o = buildOverview(art, -1);

      printText(o);

    }

    // otherwise print information about the specified range

    else

    {

      int artStart = -1;

      int artEnd   = -1;

      String[] nums = command[1].split("-");

      if(nums.length > 1)

      {

        try

        {

          artStart = Integer.parseInt(nums[0]);

        }

        catch(Exception e) 

        {

          artStart = Integer.parseInt(command[1]);

        }

        try

        {

          artEnd = Integer.parseInt(nums[1]);

        }

        catch(Exception e) {}

      }

      printStatus(224, "Overview information follows");

      for(int n = artStart; n <= artEnd; n++)

      {

        Article art = Article.getByNumberInGroup(getCurrentGroup(), n);

        if(art == null)

        {

          Debug.getInstance().log("Article (gid=" + getCurrentGroup() + ", art=" + n + " is null!");

        }

        else

        {

          printTextPart(buildOverview(art, n) + NEWLINE);

        }

      }

      println(".");

      flush();

    }

    return true;

  }

  private String buildOverview(Article art, int nr)

  {

    SimpleDateFormat sdf = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss Z", Locale.US);

    StringBuilder overview = new StringBuilder();

    overview.append(nr);

    overview.append('\t');

    overview.append(art.getHeader().get("Subject"));

    overview.append('\t');

    overview.append(art.getHeader().get("From"));

    overview.append('\t');

    overview.append(sdf.format(art.getDate()));

    overview.append('\t');

    overview.append(art.getHeader().get("Message-ID"));

    overview.append('\t');

    overview.append(art.getHeader().get("References"));

    overview.append('\t');

    overview.append(art.getHeader().get("Bytes"));

    overview.append('\t');

    overview.append(art.getHeader().get("Lines"));

    return overview.toString();

  }

}