/*
    Copyright (c) 2008 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_PROTOCOLHELPER_P_H
#define AKONADI_PROTOCOLHELPER_P_H

#include <akonadi/cachepolicy.h>
#include <akonadi/collection.h>
#include <akonadi/collectionutils_p.h>
#include <akonadi/item.h>
#include <akonadi/itemfetchscope.h>
#include <akonadi/sharedvaluepool_p.h>

#include <akonadi/private/imapparser_p.h>
#include <akonadi/private/protocol_p.h>

#include <boost/bind.hpp>
#include <algorithm>

namespace Akonadi {

struct ProtocolHelperValuePool
{
  typedef Internal::SharedValuePool<QByteArray, QVector> FlagPool;
  typedef Internal::SharedValuePool<QString, QVector> MimeTypePool;

  FlagPool flagPool;
  MimeTypePool mimeTypePool;
  QHash<Collection::Id, Collection> ancestorCollections;
};
  
/**
  @internal
  Helper methods for converting between libakonadi objects and their protocol
  representation.

  @todo Add unit tests for this.
  @todo Use exceptions for a useful error handling
*/
class ProtocolHelper
{
  public:
    /** Part namespaces. */
    enum PartNamespace {
      PartGlobal,
      PartPayload,
      PartAttribute
    };

    /**
      Parse a cache policy definition.
      @param data The input data.
      @param policy The parsed cache policy.
      @param start Start of the data, ie. postion after the label.
      @returns Position in data after the cache policy description.
    */
    static int parseCachePolicy( const QByteArray &data, CachePolicy &policy, int start = 0 );

    /**
      Convert a cache policy object into its protocol representation.
    */
    static QByteArray cachePolicyToByteArray( const CachePolicy &policy );

    /**
      Convert a ancestor chain from its protocol representation into an Entity object.
    */
    static void parseAncestors( const QByteArray &data, Entity *entity, int start = 0 );

    /**
      Convert a ancestor chain from its protocol representation into an Entity object.

      This method allows to pass a @p valuePool which acts as cache, so ancestor paths for the
      same @p parentCollection don't have to be parsed twice.
    */
    static void parseAncestorsCached( const QByteArray &data, Entity *entity, Collection::Id parentCollection, ProtocolHelperValuePool *valuePool = 0, int start = 0 );

    /**
      Parse a collection description.
      @param data The input data.
      @param collection The parsed collection.
      @param start Start of the data.
      @returns Position in data after the collection description.
    */
    static int parseCollection( const QByteArray &data, Collection &collection, int start = 0 );

    /**
      Convert attributes to their protocol representation.
    */
    static QByteArray attributesToByteArray( const Entity &entity, bool ns = false );

    /**
      Encodes part label and namespace.
    */
    static QByteArray encodePartIdentifier( PartNamespace ns, const QByteArray &label, int version = 0 );

    /**
      Decode part label and namespace.
    */
    static QByteArray decodePartIdentifier( const QByteArray &data, PartNamespace &ns );

    /**
      Converts the given set of items into a protocol representation.
      @throws A Akonadi::Exception if the item set contains items with missing/invalid identifiers.
    */
    template <typename T>
    static QByteArray entitySetToByteArray( const QList<T> &_objects, const QByteArray &command )
    {
      if ( _objects.isEmpty() )
        throw Exception( "No objects specified" );

      typename T::List objects( _objects );

      QByteArray rv;
      std::sort( objects.begin(), objects.end(), boost::bind( &T::id, _1 ) < boost::bind( &T::id, _2 ) );
      if ( objects.first().isValid() ) {
        // all items have a uid set
        rv += " " AKONADI_CMD_UID " ";
        if ( !command.isEmpty() ) {
          rv += command;
          rv += ' ';
        }
        QVector<typename T::Id>  uids;
        foreach ( const T &object, objects )
          uids << object.id();
        ImapSet set;
        set.add( uids );
        rv += set.toImapSequenceSet();
        return rv;
      }

      // check if all items have a remote id
      if ( std::find_if( objects.constBegin(), objects.constEnd(),
            boost::bind( &QString::isEmpty, boost::bind( &T::remoteId, _1 ) ) )
            != objects.constEnd() )
      {
        throw Exception( "No remote identifier specified" );
      }

      // check if we have RIDs or HRIDs
      if ( std::find_if( objects.constBegin(), objects.constEnd(),
            !boost::bind( static_cast<bool (*)(const T&)>( &CollectionUtils::hasValidHierarchicalRID ), _1 ) )
          == objects.constEnd() && objects.size() == 1 ) // ### HRID sets are not yet specified
      {
        // HRIDs
        rv += " " AKONADI_CMD_HRID " ";
        if ( !command.isEmpty() ) {
          rv += command;
          rv += ' ';
        }
        rv += '(' + hierarchicalRidToByteArray( objects.first() ) + ')';
        return rv;
      }

      // RIDs
      QList<QByteArray> rids;
      foreach ( const T &object, objects ) {
        rids << ImapParser::quote( object.remoteId().toUtf8() );
      }

      rv += " " AKONADI_CMD_RID " ";
      if ( !command.isEmpty() ) {
        rv += command;
        rv += ' ';
      }
      rv += '(';
      rv += ImapParser::join( rids, " " );
      rv += ')';
      return rv;
    }

    /**
      Converts the given object identifier into a protocol representation.
      @throws A Akonadi::Exception if the item set contains items with missing/invalid identifiers.
    */
    template <typename T>
    static QByteArray entityIdToByteArray( const T &object, const QByteArray &command )
    {
      return entitySetToByteArray( typename T::List() << object, command );
    }

    /**
      Converts the given collection's hierarchical RID into a protocol representation.
      Assumes @p col has a valid hierarchical RID, so check that before!
    */
    static QByteArray hierarchicalRidToByteArray( const Collection &col );

    /**
      Converts the HRID of the given item into an ASAP protocol representation.
      Assumes @p item has a valid HRID.
    */
    static QByteArray hierarchicalRidToByteArray( const Item &item );

    /**
      Converts a given ItemFetchScope object into a protocol representation.
    */
    static QByteArray itemFetchScopeToByteArray( const ItemFetchScope &fetchScope );

    /**
      Parses a single line from an item fetch job result into an Item object.
     */
    static void parseItemFetchResult( const QList<QByteArray> &lineTokens, Item &item, ProtocolHelperValuePool *valuePool = 0 );
};

}

#endif