/*

 *   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 java.util.Date;

import java.util.List;

import org.sonews.daemon.AbstractDaemon;

import org.sonews.config.Config;

import org.sonews.storage.Article;

import org.sonews.storage.Headers;

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.get().warning("Purger interrupted: " + ex);

		}

	}

	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.get().info("Group " + group.getName() + " purged.");

				}

				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.get().info("Article " + art.getMessageID() + " purged.");

				}

			}

		}

	}

	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.get().info("Purging old messages...");

			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.get().warning("Could not parse date string: " + dateStr + " " + ex);

			}

			// 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.get().info("Lifetime purger is disabled");

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

		}

	}

}