/*

 *   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;

import org.sonews.daemon.AbstractDaemon;

import org.sonews.config.Config;

import org.sonews.storage.Article;

import org.sonews.storage.Headers;

import java.util.Date;

import java.util.List;

import org.sonews.storage.Channel;

import org.sonews.storage.Group;

import org.sonews.storage.StorageBackendException;

import org.sonews.storage.StorageManager;

/**

 * The purger is started in configurable intervals to search

 * for messages that can be purged. A message must be deleted if its lifetime

 * has exceeded, if it was marked as deleted or if the maximum number of

 * articles in the database is reached.

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public class Purger extends AbstractDaemon

{

  /**

   * Loops through all messages and deletes them if their time

   * has come.

   */

  @Override

  public void run()

  {

    try

    {

      while(isRunning())

      {

        purgeDeleted();

        purgeOutdated();

        Thread.sleep(120000); // Sleep for two minutes

      }

    }

    catch(StorageBackendException ex)

    {

      ex.printStackTrace();

    }

    catch(InterruptedException ex)

    {

      Log.msg("Purger interrupted: " + ex, true);

    }

  }

  private void purgeDeleted()

    throws StorageBackendException

  {

    List<Channel> groups = StorageManager.current().getGroups();

    for(Channel channel : groups)

    {

      if(!(channel instanceof Group))

        continue;

      Group group = (Group)channel;

      // Look for groups that are marked as deleted

      if(group.isDeleted())

      {

        List<Long> ids = StorageManager.current().getArticleNumbers(group.getInternalID());

        if(ids.size() == 0)

        {

          StorageManager.current().purgeGroup(group);

          Log.msg("Group " + group.getName() + " purged.", true);

        }

        for(int n = 0; n < ids.size() && n < 10; n++)

        {

          Article art = StorageManager.current().getArticle(ids.get(n), group.getInternalID());

          StorageManager.current().delete(art.getMessageID());

          Log.msg("Article " + art.getMessageID() + " purged.", true);

        }

      }

    }

  }

  private void purgeOutdated()

    throws InterruptedException, StorageBackendException

  {

    long articleMaximum =

      Config.inst().get("sonews.article.maxnum", Long.MAX_VALUE);

    long lifetime =

      Config.inst().get("sonews.article.lifetime", -1);

    if(lifetime > 0 || articleMaximum < Stats.getInstance().getNumberOfNews())

    {

      Log.msg("Purging old messages...", true);

      String mid = StorageManager.current().getOldestArticle();

      if (mid == null) // No articles in the database

      {

        return;

      }

      Article art = StorageManager.current().getArticle(mid);

      long artDate = 0;

      String dateStr = art.getHeader(Headers.DATE)[0];

      try

      {

        artDate = Date.parse(dateStr) / 1000 / 60 / 60 / 24;

      }

      catch (IllegalArgumentException ex)

      {

        Log.msg("Could not parse date string: " + dateStr + " " + ex, true);

      }

      // Should we delete the message because of its age or because the

      // article maximum was reached?

      if (lifetime < 0 || artDate < (new Date().getTime() + lifetime))

      {

        StorageManager.current().delete(mid);

        System.out.println("Deleted: " + mid);

      }

      else

      {

        Thread.sleep(1000 * 60); // Wait 60 seconds

        return;

      }

    }

    else

    {

      Log.msg("Lifetime purger is disabled", true);

      Thread.sleep(1000 * 60 * 30); // Wait 30 minutes

    }

  }

}