/*
    * Copyright (c) 1998-2002 The Jgroup Team.
    *
    * This program is free software; you can redistribute it and/or modify
    * it under the terms of the GNU Lesser General Public License version 2 as
    * published by the Free Software Foundation.
    *
    * 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 Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   *
   */
  
  package jgroup.relacs.daemon;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import jgroup.core.EndPoint;
  
  import org.apache.log4j.Logger;
  
  
  /**
   * The <code>GroupTable</code> class
   *
   * @author  Alberto Montresor
   * @since   Jgroup 1.2
   */
  final class GroupTable
  {
  
    ////////////////////////////////////////////////////////////////////////////////////////////
    // Logger
    ////////////////////////////////////////////////////////////////////////////////////////////
  
    /** Obtain logger for this class */
    private static final Logger log = Logger.getLogger(GroupTable.class);
  
  
    ////////////////////////////////////////////////////////////////////////////////////////////
    // Fields
    ////////////////////////////////////////////////////////////////////////////////////////////
  
    /** Hash table containing the groups in the system */
    private final Map<Integer,Group> totgroups = new HashMap<Integer,Group>();
  
    /** Hash map: host to a list of Group objects on that host */
    private final Map<EndPoint,List<Group>> grouplists = new HashMap<EndPoint,List<Group>>();
  
    /** Hash table that maps host to symmetry sets */ 
    private final Map<EndPoint,EndPoint[]> symsets = new HashMap<EndPoint,EndPoint[]>();
  
  
    ////////////////////////////////////////////////////////////////////////////////////////////
    // Constructors
    ////////////////////////////////////////////////////////////////////////////////////////////
  
    GroupTable() { }
  
  
    ////////////////////////////////////////////////////////////////////////////////////////////
    // Methods
    ////////////////////////////////////////////////////////////////////////////////////////////
  
    @Override
    public String toString()
    {
      StringBuilder buf = new StringBuilder("GroupTable: groups=");
      for (Group group : totgroups.values()) {
        buf.append(group.getGid());
        buf.append(" ");
      }
      for (Map.Entry<EndPoint,List<Group>> groupEntry : grouplists.entrySet()) {
        buf.append("endpoint=");
        buf.append(groupEntry.getKey());
        buf.append(": ");
        for (Group group : groupEntry.getValue()) {
          buf.append(group.getGid());
        }
        buf.append("; ");
      }
      return buf.toString();
    }
  
    /**
     *  Add a new host/endpoint to the given group.
     */
    void addEndpointToGroup(EndPoint endpoint, Group group)
    {
      if (log.isDebugEnabled()) 
       log.debug("GroupTable: addGroupEndPoint: " + endpoint);
     if (!containsGroup(group.getGid()))
       throw new IllegalStateException("Cannot add group endpoint to a non-local group.");
     List<Group> groups = grouplists.get(endpoint);
     if (groups == null) {
       groups = new ArrayList<Group>(10);
       grouplists.put(endpoint, groups);
     }
     if (!groups.contains(group))
       groups.add(group);
 
     if (log.isDebugEnabled())
       log.debug(toString());
   }
 
   /**
    *  Insert a new group in the group table.
    */
   void insertGroup(Group group)
   {
     totgroups.put(group.getGid(), group);
   }
 
   /**
    *  Remove the given group from the group table.
    */
   void removeGroup(int gid)
   {
     if (log.isDebugEnabled())
       log.debug("Removing group: " + gid);
 
     Group group = getGroup(gid);
     for (Iterator iter = grouplists.entrySet().iterator(); iter.hasNext();) {
       Map.Entry groupEntry = (Map.Entry) iter.next();
       List groups = (List) groupEntry.getValue();
       groups.remove(group);
       if (log.isDebugEnabled())
         log.debug("Removed group " + group.getGid() + " from host " + groupEntry.getKey());
       if (groups.isEmpty())
         iter.remove();
     }
     totgroups.remove(gid);
 
     if (log.isDebugEnabled())
       log.debug(toString());
   }
 
   /**
    *  Return the group object for the given group identifier.
    */
   Group getGroup(int gid)
   {
     return totgroups.get(gid);
   }
 
   /**
    *  Returns true if the given group is contained in this group table.
    */
   boolean containsGroup(int gid)
   {
     return totgroups.containsKey(gid);
   }
 
   /**
    *  Returns true if the group table contains no local group members.
    */
   boolean isEmpty()
   {
     return totgroups.isEmpty();
   }
     
   /**
    *  Returns an iterator containing all the the groups contained in
    *  this group table.
    */
   Iterator iterator()
   {
     return totgroups.values().iterator();
   }
   
   /**
    *  Returns an iterator containing the list of groups
    *  joined by the specified host.
    */
   Iterator getGroups(EndPoint endpoint) 
   {
     List<Group> groups = grouplists.get(endpoint);
     /* 
      * Ensures that we return an empty iterator if there are no groups
      * for the specified host.
      */
     if (groups == null)
       groups = new ArrayList<Group>(0);
     return groups.iterator();
   }
 
   EndPoint[] getSymset(EndPoint endpoint)
   {
     return symsets.get(endpoint);
   }
   
   void setSymset(EndPoint host, EndPoint[] symset)
   {
     symsets.put(host, symset);
   }
 
 } // END GroupTable