/*

  *   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.storage;

 import java.util.ArrayList;

 import java.util.List;

 import org.sonews.util.Pair;

 /**

  * A logical communication Channel is the a generic structural element for sets

  * of messages; e.g. a Newsgroup for a set of Articles.

  * A Channel can either be a real set of messages or an aggregated set of

  * several subsets.

  * @author Christian Lins

  * @since sonews/1.0

  */

 public abstract class Channel

 {

   /**

    * If this flag is set the Group is no real newsgroup but a mailing list

    * mirror. In that case every posting and receiving mails must go through

    * the mailing list gateway.

    */

   public static final int MAILINGLIST = 0x1;

   /**

    * If this flag is set the Group is marked as readonly and the posting

    * is prohibited. This can be useful for groups that are synced only in

    * one direction.

    */

   public static final int READONLY    = 0x2;

   /**

    * If this flag is set the Group is marked as deleted and must not occur

    * in any output. The deletion is done lazily by a low priority daemon.

    */

   public static final int DELETED     = 0x80;

   public static List<Channel> getAll()

   {

     List<Channel> all = new ArrayList<Channel>();

     /*List<Channel> agroups = AggregatedGroup.getAll();

     if(agroups != null)

     {

       all.addAll(agroups);

     }*/

     List<Channel> groups = Group.getAll();

     if(groups != null)

     {

       all.addAll(groups);

     }

     return all;

   }

   public static Channel getByName(String name)

   {

     Channel channel;

     // Check if it's an aggregated group

     channel = AggregatedGroup.getByName(name);

     // If it's not an aggregate is probably a "real" group

     if(channel == null)

     {

       channel = Group.getByName(name);

     }

     return channel;

   }

   public abstract Article getArticle(long idx)

     throws StorageBackendException;

   public abstract List<Pair<Long, ArticleHead>> getArticleHeads(

     final long first, final long last)

     throws StorageBackendException;

   public abstract List<Long> getArticleNumbers()

     throws StorageBackendException;

   public abstract long getFirstArticleNumber()

     throws StorageBackendException;

   public abstract long getIndexOf(Article art)

     throws StorageBackendException;

   public abstract long getInternalID();

   public abstract long getLastArticleNumber()

     throws StorageBackendException;

   public abstract String getName();

   public abstract long getPostingsCount()

     throws StorageBackendException;

   public abstract boolean isDeleted();

   public abstract boolean isWriteable();

 }