/**
 *   Copyright 2011-2015 Quickstep Technologies LLC.
 *   Copyright 2015 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.
 **/

#include "expressions/aggregation/AggregationHandleMin.hpp"

#include <memory>
#include <vector>

#include "catalog/CatalogTypedefs.hpp"
#include "storage/HashTable.hpp"
#include "storage/HashTableFactory.hpp"
#include "types/Type.hpp"
#include "types/TypedValue.hpp"
#include "types/containers/ColumnVector.hpp"
#include "types/operations/comparisons/Comparison.hpp"
#include "types/operations/comparisons/ComparisonFactory.hpp"
#include "types/operations/comparisons/ComparisonID.hpp"

#include "glog/logging.h"

namespace quickstep {

class StorageManager;

AggregationHandleMin::AggregationHandleMin(const Type &type)
    : type_(type) {
  fast_comparator_.reset(ComparisonFactory::GetComparison(ComparisonID::kLess)
                         .makeUncheckedComparatorForTypes(type,
                                                          type.getNonNullableVersion()));
}

AggregationStateHashTableBase* AggregationHandleMin::createGroupByHashTable(
    const HashTableImplType hash_table_impl,
    const std::vector<const Type*> &group_by_types,
    const std::size_t estimated_num_groups,
    StorageManager *storage_manager) const {
  return AggregationStateHashTableFactory<AggregationStateMin>::CreateResizable(
      hash_table_impl,
      group_by_types,
      estimated_num_groups,
      storage_manager);
}

AggregationState* AggregationHandleMin::accumulateColumnVectors(
    const std::vector<std::unique_ptr<ColumnVector>> &column_vectors) const {
  DCHECK_EQ(1u, column_vectors.size())
      << "Got wrong number of ColumnVectors for MIN: " << column_vectors.size();

  return new AggregationStateMin(
      fast_comparator_->accumulateColumnVector(type_.getNullableVersion().makeNullValue(),
                                               *column_vectors.front()));
}

#ifdef QUICKSTEP_ENABLE_VECTOR_COPY_ELISION_SELECTION
AggregationState* AggregationHandleMin::accumulateValueAccessor(
    ValueAccessor *accessor,
    const std::vector<attribute_id> &accessor_ids) const {
  DCHECK_EQ(1u, accessor_ids.size())
      << "Got wrong number of attributes for MIN: " << accessor_ids.size();

  return new AggregationStateMin(
      fast_comparator_->accumulateValueAccessor(type_.getNullableVersion().makeNullValue(),
                                                accessor,
                                                accessor_ids.front()));
}
#endif  // QUICKSTEP_ENABLE_VECTOR_COPY_ELISION_SELECTION

void AggregationHandleMin::aggregateValueAccessorIntoHashTable(
    ValueAccessor *accessor,
    const std::vector<attribute_id> &argument_ids,
    const std::vector<attribute_id> &group_by_key_ids,
    AggregationStateHashTableBase *hash_table) const {
  DCHECK_EQ(1u, argument_ids.size())
      << "Got wrong number of arguments for MIN: " << argument_ids.size();

  aggregateValueAccessorIntoHashTableUnaryHelper<
      AggregationHandleMin,
      AggregationStateMin,
      AggregationStateHashTable<AggregationStateMin>>(
          accessor,
          argument_ids.front(),
          group_by_key_ids,
          AggregationStateMin(type_),
          hash_table);
}

void AggregationHandleMin::mergeStates(
    const AggregationState &source,
    AggregationState *destination) const {
  const AggregationStateMin &min_source = static_cast<const AggregationStateMin&>(source);
  AggregationStateMin *min_destination = static_cast<AggregationStateMin*>(destination);

  if (!min_source.min_.isNull()) {
    compareAndUpdate(min_destination, min_source.min_);
  }
}

ColumnVector* AggregationHandleMin::finalizeHashTable(
    const AggregationStateHashTableBase &hash_table,
    std::vector<std::vector<TypedValue>> *group_by_keys) const {
  return finalizeHashTableHelper<AggregationHandleMin,
                                 AggregationStateHashTable<AggregationStateMin>>(
      type_.getNonNullableVersion(),
      hash_table,
      group_by_keys);
}

}  // namespace quickstep