/**
 *   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_SELECT_OPERATOR_HPP_
#define QUICKSTEP_RELATIONAL_OPERATORS_SELECT_OPERATOR_HPP_

#include <memory>
#include <utility>
#include <vector>

#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/StorageBlockInfo.hpp"
#include "utility/Macros.hpp"

#include "glog/logging.h"

#include "tmb/id_typedefs.h"

namespace tmb { class MessageBus; }

namespace quickstep {

class CatalogRelationSchema;
class InsertDestination;
class Predicate;
class Scalar;
class StorageManager;
class WorkOrdersContainer;

/** \addtogroup RelationalOperators
 *  @{
 */

/**
 * @brief An operator which performs simple selection over a relation.
 **/
class SelectOperator : public RelationalOperator {
 public:
  /**
   * @brief Constructor for selection with arbitrary expressions in projection
   *        list.
   *
   * @param input_relation The relation to perform selection over.
   * @param output_relation The output relation.
   * @param output_destination_index The index of the InsertDestination in the
   *        QueryContext to insert the selection results.
   * @param predicate_index The index of selection predicate in QueryContext.
   *        All tuples matching pred will be selected (or kInvalidPredicateId to
   *        select all tuples).
   * @param selection_index The group index of Scalars in QueryContext, which
   *        will be evaluated to project input tuples.
   * @param input_relation_is_stored If input_relation is a stored relation and
   *        is fully available to the operator before it can start generating
   *        workorders.
   **/
  SelectOperator(const CatalogRelation &input_relation,
                 const CatalogRelation &output_relation,
                 const QueryContext::insert_destination_id output_destination_index,
                 const QueryContext::predicate_id predicate_index,
                 const QueryContext::scalar_group_id selection_index,
                 const bool input_relation_is_stored)
      : input_relation_(input_relation),
        output_relation_(output_relation),
        output_destination_index_(output_destination_index),
        predicate_index_(predicate_index),
        selection_index_(selection_index),
        input_relation_block_ids_(input_relation_is_stored ? input_relation.getBlocksSnapshot()
                                                           : std::vector<block_id>()),
        num_workorders_generated_(0),
        simple_projection_(false),
        input_relation_is_stored_(input_relation_is_stored),
        started_(false) {}

  /**
   * @brief Constructor for selection with simple projection of attributes.
   *
   * @note selection_index_ is invalid, and will not be used for projection.
   *
   * @param input_relation The relation to perform selection over.
   * @param output_relation The output relation.
   * @param output_destination_index The index of the InsertDestination in the
   *        QueryContext to insert the selection results.
   * @param selection A projection list of attribute IDs. The operator takes
   *        ownership of selection.
   * @param predicate_index The index of selection predicate in QueryContext.
   *        All tuples matching pred will be selected (or kInvalidPredicateId to
   *        select all tuples).
   * @param input_relation_is_stored If input_relation is a stored relation and
   *        is fully available to the operator before it can start generating
   *        workorders.
   **/
  SelectOperator(const CatalogRelation &input_relation,
                 const CatalogRelation &output_relation,
                 const QueryContext::insert_destination_id output_destination_index,
                 const QueryContext::predicate_id predicate_index,
                 std::vector<attribute_id> &&selection,
                 const bool input_relation_is_stored)
      : input_relation_(input_relation),
        output_relation_(output_relation),
        output_destination_index_(output_destination_index),
        predicate_index_(predicate_index),
        selection_index_(QueryContext::kInvalidScalarGroupId),
        simple_selection_(std::move(selection)),
        input_relation_block_ids_(input_relation_is_stored ? input_relation.getBlocksSnapshot()
                                                           : std::vector<block_id>()),
        num_workorders_generated_(0),
        simple_projection_(true),
        input_relation_is_stored_(input_relation_is_stored),
        started_(false) {}

  ~SelectOperator() override {}

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

  void feedInputBlock(const block_id input_block_id, const relation_id input_relation_id) override {
    input_relation_block_ids_.push_back(input_block_id);
  }

  void feedInputBlocks(const relation_id rel_id, std::vector<block_id> *partially_filled_blocks) override {
    input_relation_block_ids_.insert(input_relation_block_ids_.end(),
                                     partially_filled_blocks->begin(),
                                     partially_filled_blocks->end());
  }

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

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

 private:
  const CatalogRelation &input_relation_;

  const CatalogRelation &output_relation_;
  const QueryContext::insert_destination_id output_destination_index_;
  const QueryContext::predicate_id predicate_index_;

  const QueryContext::scalar_group_id selection_index_;
  const std::vector<attribute_id> simple_selection_;

  std::vector<block_id> input_relation_block_ids_;

  // A single workorder is generated for each block of input relation.
  std::vector<block_id>::size_type num_workorders_generated_;

  const bool simple_projection_;
  const bool input_relation_is_stored_;
  bool started_;

  DISALLOW_COPY_AND_ASSIGN(SelectOperator);
};

/**
 * @brief A WorkOrder produced by SelectOperator.
 **/
class SelectWorkOrder : public WorkOrder {
 public:
  /**
   * @brief Constructor.
   *
   * @note Reference parameter selection is NOT owned by this class and must
   *       remain valid until after execute() is called.
   *
   * @param input_relation The relation to perform selection over.
   * @param input_block_id The block id.
   * @param predicate All tuples matching \c predicate will be selected (or NULL
   *        to select all tuples).
   * @param simple_projection Whether the Select is simple.
   * @param simple_selection The list of attribute ids, used if \c
   *        simple_projection is true.
   * @param selection A list of Scalars which will be evaluated to project
   *        input tuples, used if \c simple_projection is false.
   * @param output_destination The InsertDestination to insert the selection
   *        results.
   * @param storage_manager The StorageManager to use.
   **/
  SelectWorkOrder(const CatalogRelationSchema &input_relation,
                  const block_id input_block_id,
                  const Predicate *predicate,
                  const bool simple_projection,
                  const std::vector<attribute_id> &simple_selection,
                  const std::vector<std::unique_ptr<const Scalar>> *selection,
                  InsertDestination *output_destination,
                  StorageManager *storage_manager)
      : input_relation_(input_relation),
        input_block_id_(input_block_id),
        predicate_(predicate),
        simple_projection_(simple_projection),
        simple_selection_(simple_selection),
        selection_(selection),
        output_destination_(DCHECK_NOTNULL(output_destination)),
        storage_manager_(DCHECK_NOTNULL(storage_manager)) {}

  /**
   * @brief Constructor for the distributed version.
   *
   * @note Reference parameter selection is NOT owned by this class and must
   *       remain valid until after execute() is called.
   *
   * @param input_relation The relation to perform selection over.
   * @param input_block_id The block id.
   * @param predicate All tuples matching \c predicate will be selected (or NULL
   *        to select all tuples).
   * @param simple_projection Whether the Select is simple.
   * @param simple_selection The list of attribute ids, used if \c
   *        simple_projection is true.
   * @param selection A list of Scalars which will be evaluated to project
   *        input tuples, used if \c simple_projection is false.
   * @param output_destination The InsertDestination to insert the selection
   *        results.
   * @param storage_manager The StorageManager to use.
   **/
  SelectWorkOrder(const CatalogRelationSchema &input_relation,
                  const block_id input_block_id,
                  const Predicate *predicate,
                  const bool simple_projection,
                  std::vector<attribute_id> &&simple_selection,
                  const std::vector<std::unique_ptr<const Scalar>> *selection,
                  InsertDestination *output_destination,
                  StorageManager *storage_manager)
      : input_relation_(input_relation),
        input_block_id_(input_block_id),
        predicate_(predicate),
        simple_projection_(simple_projection),
        simple_selection_(std::move(simple_selection)),
        selection_(selection),
        output_destination_(DCHECK_NOTNULL(output_destination)),
        storage_manager_(DCHECK_NOTNULL(storage_manager)) {}

  ~SelectWorkOrder() override {}

  /**
   * @exception TupleTooLargeForBlock A tuple produced by this selection was
   *            too large to insert into an empty block provided by
   *            output_destination_index_ in query_context. Select may be
   *            partially complete (with some tuples inserted into the
   *            destination) when this exception is thrown, causing potential
   *            inconsistency.
   **/
  void execute() override;

 private:
  const CatalogRelationSchema &input_relation_;
  const block_id input_block_id_;
  const Predicate *predicate_;

  const bool simple_projection_;
  const std::vector<attribute_id> simple_selection_;
  const std::vector<std::unique_ptr<const Scalar>> *selection_;

  InsertDestination *output_destination_;
  StorageManager *storage_manager_;

  DISALLOW_COPY_AND_ASSIGN(SelectWorkOrder);
};

/** @} */

}  // namespace quickstep

#endif  // QUICKSTEP_RELATIONAL_OPERATORS_SELECT_OPERATOR_HPP_