////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Max Neunhoeffer
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGOD_AQL_SORT_BLOCK_H
#define ARANGOD_AQL_SORT_BLOCK_H 1

#include "Basics/Common.h"
#include "Aql/ExecutionBlock.h"
#include "Aql/SortNode.h"

namespace arangodb {
class AqlTransaction;

namespace aql {

class AqlItemBlock;

class ExecutionEngine;

class SortBlock : public ExecutionBlock {
 public:
  SortBlock(ExecutionEngine*, SortNode const*);

  ~SortBlock();

  int initialize() override;

  int initializeCursor(AqlItemBlock* items, size_t pos) override final;

  //////////////////////////////////////////////////////////////////////////////
  /// @brief dosorting
  //////////////////////////////////////////////////////////////////////////////

 private:
  void doSorting();

  //////////////////////////////////////////////////////////////////////////////
  /// @brief OurLessThan
  //////////////////////////////////////////////////////////////////////////////

  class OurLessThan {
   public:
    OurLessThan(arangodb::AqlTransaction* trx,
                std::deque<AqlItemBlock*>& buffer,
                std::vector<std::pair<RegisterId, bool>>& sortRegisters,
                std::vector<TRI_document_collection_t const*>& colls)
        : _trx(trx),
          _buffer(buffer),
          _sortRegisters(sortRegisters),
          _colls(colls) {}

    bool operator()(std::pair<size_t, size_t> const& a,
                    std::pair<size_t, size_t> const& b);

   private:
    arangodb::AqlTransaction* _trx;
    std::deque<AqlItemBlock*>& _buffer;
    std::vector<std::pair<RegisterId, bool>>& _sortRegisters;
    std::vector<TRI_document_collection_t const*>& _colls;
  };

  //////////////////////////////////////////////////////////////////////////////
  /// @brief pairs, consisting of variable and sort direction
  /// (true = ascending | false = descending)
  //////////////////////////////////////////////////////////////////////////////

  std::vector<std::pair<RegisterId, bool>> _sortRegisters;

  //////////////////////////////////////////////////////////////////////////////
  /// @brief whether or not the sort should be stable
  //////////////////////////////////////////////////////////////////////////////

  bool _stable;
};

}  // namespace arangodb::aql
}  // namespace arangodb

#endif