/*
    Copyright (c) 2007 Volker Krause <vkrause@kde.org>

    This library is free software; you can redistribute it and/or modify it
    under the terms of the GNU Library General Public License as published by
    the Free Software Foundation; either version 2 of the License, or (at your
    option) any later version.

    This library 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 Library General Public
    License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to the
    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
    02110-1301, USA.
*/

#ifndef AKONADI_NOTIFICATIONMESSAGEV2_P_H
#define AKONADI_NOTIFICATIONMESSAGEV2_P_H

#include "notificationmessagev2_p.h"

namespace Akonadi
{

class NotificationMessageHelpers
{
  public:
    template<typename T>
    static bool compareWithoutOpAndParts( const T &left, const T &right )
    {
      return left.entities() == right.entities()
          && left.type() == right.type()
          && left.sessionId() == right.sessionId()
          && left.resource() == right.resource()
          && left.destinationResource() == right.destinationResource()
          && left.parentCollection() == right.parentCollection()
          && left.parentDestCollection() == right.parentDestCollection();
    }

    template<typename List, typename Msg>
    static bool appendAndCompressImpl( List &list, const Msg &msg )
    {
      // fast-path for stuff that is not considered during O(n) compression below
      if ( msg.operation() != NotificationMessageV2::Add && msg.operation() != NotificationMessageV2::Link
          && msg.operation() != NotificationMessageV2::Unlink && msg.operation() != NotificationMessageV2::Subscribe
          && msg.operation() != NotificationMessageV2::Unsubscribe && msg.operation() != NotificationMessageV2::Move ) {

        typename List::Iterator end = list.end();
        for ( typename List::Iterator it = list.begin(); it != end; ) {
          if ( compareWithoutOpAndParts( msg, ( *it ) ) ) {

            // both are modifications, merge them together and drop the new one
            if ( msg.operation() == NotificationMessageV2::Modify && it->operation() == NotificationMessageV2::Modify ) {
              ( *it ).setItemParts( ( *it ).itemParts() + msg.itemParts() );
              return false;
            }

            else if ( msg.operation() == NotificationMessageV2::ModifyFlags && it->operation() == NotificationMessageV2::ModifyFlags ) {
              ( *it ).setAddedFlags( ( *it ).addedFlags() + msg.addedFlags() );
              ( *it ).setRemovedFlags( ( *it ).removedFlags() + msg.removedFlags() );

               // If merged notifications result in no-change notification, drop both.
              if ( ( *it ).addedFlags() == ( *it ).removedFlags() ) {
                it = list.erase( it );
                end = list.end();
              }

              return false;
            }

            else if ( msg.operation() == NotificationMessageV2::ModifyTags && it->operation() == NotificationMessageV2::ModifyTags ) {
              ( *it ).setAddedTags( ( *it ).addedTags() + msg.addedTags() );
              ( *it ).setRemovedTags( ( *it ).removedTags() + msg.removedTags() );

              // If merged notification results in no-change notification, drop both
              if ( ( *it ).addedTags() == ( *it ).removedTags() ) {
                it = list.erase( it );
                end = list.end();
              }

              return false;
            }
            // new one is a modification, the existing one not, so drop the new one
            else if ( ( ( msg.operation() == NotificationMessageV2::Modify ) || ( msg.operation() == NotificationMessageV2::ModifyFlags ) )
              && ( ( *it ).operation() != NotificationMessageV2::Modify )
              && ( *it ).operation() != NotificationMessageV2::ModifyFlags
              && ( *it ).operation() != NotificationMessageV2::ModifyTags ) {
              return false;
            }
            // new one is a deletion, erase the existing modification ones (and keep going, in case there are more)
            else if ( msg.operation() == NotificationMessageV2::Remove && ( ( *it ).operation() == NotificationMessageV2::Modify || ( *it ).operation() == NotificationMessageV2::ModifyFlags || ( *it ).operation() == NotificationMessageV2::ModifyTags ) ) {
              it = list.erase( it );
              end = list.end();
            }
            // keep looking
            else {
              ++it;
            }
          } else {
            ++it;
          }
        }
      }

      list.append( msg );
      return true;
    }
};

}

#endif