/**
 *   Copyright 2011-2015 Quickstep Technologies LLC.
 *   Copyright 2015-2016 Pivotal Software, Inc.
 *
 *   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.
 **/

#ifndef QUICKSTEP_RELATIONAL_OPERATORS_FINALIZE_AGGREGATION_OPERATOR_HPP_
#define QUICKSTEP_RELATIONAL_OPERATORS_FINALIZE_AGGREGATION_OPERATOR_HPP_

#include <memory>

#include "catalog/CatalogRelation.hpp"
#include "catalog/CatalogTypedefs.hpp"
#include "query_execution/QueryContext.hpp"
#include "relational_operators/RelationalOperator.hpp"
#include "relational_operators/WorkOrder.hpp"
#include "storage/AggregationOperationState.hpp"
#include "utility/Macros.hpp"

#include "glog/logging.h"

#include "tmb/id_typedefs.h"

namespace tmb { class MessageBus; }

namespace quickstep {

class InsertDestination;
class StorageManager;
class WorkOrdersContainer;

/** \addtogroup RelationalOperators
 *  @{
 */

/**
 * @brief An operator which finalizes aggregation and writes output tuples.
 */
class FinalizeAggregationOperator : public RelationalOperator {
 public:
  /**
   * @brief Constructor for finalizing aggregation state and writing output
   * tuples.  The actual aggregation is computed by the AggregationOperator.
   *
   * @param aggr_state_index The index of the AggregationState in QueryContext.
   * @param output_relation The output relation.
   * @param output_destination_index The index of the InsertDestination in the
   *        QueryContext to insert aggregation results.
   */
  FinalizeAggregationOperator(const QueryContext::aggregation_state_id aggr_state_index,
                              const CatalogRelation &output_relation,
                              const QueryContext::insert_destination_id output_destination_index)
      : aggr_state_index_(aggr_state_index),
        output_relation_(output_relation),
        output_destination_index_(output_destination_index),
        started_(false) {}

  ~FinalizeAggregationOperator() override {}

  bool getAllWorkOrders(WorkOrdersContainer *container,
                        QueryContext *query_context,
                        StorageManager *storage_manager,
                        const tmb::client_id scheduler_client_id,
                        tmb::MessageBus *bus) override;

  QueryContext::insert_destination_id getInsertDestinationID() const override {
    return output_destination_index_;
  }

  const relation_id getOutputRelationID() const override {
    return output_relation_.getID();
  }

 private:
  const QueryContext::aggregation_state_id aggr_state_index_;
  const CatalogRelation &output_relation_;
  const QueryContext::insert_destination_id output_destination_index_;
  bool started_;

  DISALLOW_COPY_AND_ASSIGN(FinalizeAggregationOperator);
};

/**
 * @brief A WorkOrder produced by FinalizeAggregationOperator.
 **/
class FinalizeAggregationWorkOrder : public WorkOrder {
 public:
  /**
   * @brief Constructor.
   *
   * @note InsertWorkOrder takes ownership of \c state.
   *
   * @param state The AggregationState to use.
   * @param output_destination The InsertDestination to insert aggregation
   *        results.
   */
  FinalizeAggregationWorkOrder(AggregationOperationState *state,
                               InsertDestination *output_destination)
      : state_(DCHECK_NOTNULL(state)),
        output_destination_(DCHECK_NOTNULL(output_destination)) {}

  ~FinalizeAggregationWorkOrder() override {}

  void execute() override;

 private:
  std::unique_ptr<AggregationOperationState> state_;
  InsertDestination *output_destination_;

  DISALLOW_COPY_AND_ASSIGN(FinalizeAggregationWorkOrder);
};

/** @} */

}  // namespace quickstep

#endif  // QUICKSTEP_RELATIONAL_OPERATORS_FINALIZE_AGGREGATION_OPERATOR_HPP_