/**
 *   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/AggregationHandleCount.hpp"

#include <atomic>
#include <cstddef>
#include <memory>
#include <vector>

#include "catalog/CatalogTypedefs.hpp"
#include "storage/HashTable.hpp"
#include "storage/HashTableFactory.hpp"

#ifdef QUICKSTEP_ENABLE_VECTOR_COPY_ELISION_SELECTION
#include "storage/ValueAccessor.hpp"
#include "storage/ValueAccessorUtil.hpp"
#endif

#include "types/TypeFactory.hpp"
#include "types/TypeID.hpp"
#include "types/TypedValue.hpp"
#include "types/containers/ColumnVector.hpp"
#include "types/containers/ColumnVectorUtil.hpp"

#include "glog/logging.h"

namespace quickstep {

class StorageManager;
class Type;
class ValueAccessor;

template <bool count_star, bool nullable_type>
AggregationStateHashTableBase*
    AggregationHandleCount<count_star, nullable_type>::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<AggregationStateCount>::CreateResizable(
      hash_table_impl,
      group_by_types,
      estimated_num_groups,
      storage_manager);
}

template <bool count_star, bool nullable_type>
AggregationState*
    AggregationHandleCount<count_star, nullable_type>::accumulateColumnVectors(
        const std::vector<std::unique_ptr<ColumnVector>> &column_vectors) const {
  DCHECK(!count_star)
      << "Called non-nullary accumulation method on an AggregationHandleCount "
      << "set up for nullary COUNT(*)";

  DCHECK_EQ(1u, column_vectors.size())
      << "Got wrong number of ColumnVectors for COUNT: " << column_vectors.size();

  std::size_t count = 0;
  InvokeOnColumnVector(
      *column_vectors.front(),
      [&](const auto &column_vector) -> void {  // NOLINT(build/c++11)
    if (nullable_type) {
      // TODO(shoban): Iterating over the ColumnVector is a rather slow way to
      // do this. We should look at extending the ColumnVector interface to do
      // a quick count of the non-null values (i.e. the length minus the
      // population count of the null bitmap). We should do something similar
      // for ValueAccessor too.
      for (std::size_t pos = 0;
           pos < column_vector.size();
           ++pos) {
        count += !column_vector.getTypedValue(pos).isNull();
      }
    } else {
      count = column_vector.size();
    }
  });

  return new AggregationStateCount(count);
}

#ifdef QUICKSTEP_ENABLE_VECTOR_COPY_ELISION_SELECTION
template <bool count_star, bool nullable_type>
AggregationState*
    AggregationHandleCount<count_star, nullable_type>::accumulateValueAccessor(
        ValueAccessor *accessor,
        const std::vector<attribute_id> &accessor_ids) const {
  DCHECK(!count_star)
      << "Called non-nullary accumulation method on an AggregationHandleCount "
      << "set up for nullary COUNT(*)";

  DCHECK_EQ(1u, accessor_ids.size())
      << "Got wrong number of attributes for COUNT: " << accessor_ids.size();

  const attribute_id accessor_id = accessor_ids.front();
  std::size_t count = 0;
  InvokeOnValueAccessorMaybeTupleIdSequenceAdapter(
      accessor,
      [&](auto *accessor) -> void {  // NOLINT(build/c++11)
    if (nullable_type) {
      while (accessor->next()) {
        count += !accessor->getTypedValue(accessor_id).isNull();
      }
    } else {
      count = accessor->getNumTuples();
    }
  });

  return new AggregationStateCount(count);
}
#endif

template <bool count_star, bool nullable_type>
    void AggregationHandleCount<count_star, nullable_type>::aggregateValueAccessorIntoHashTable(
        ValueAccessor *accessor,
        const std::vector<attribute_id> &argument_ids,
        const std::vector<attribute_id> &group_by_key_ids,
        AggregationStateHashTableBase *hash_table) const {
  if (count_star) {
    DCHECK_EQ(0u, argument_ids.size())
        << "Got wrong number of arguments for COUNT(*): " << argument_ids.size();
    aggregateValueAccessorIntoHashTableNullaryHelper<
        AggregationHandleCount<count_star, nullable_type>,
        AggregationStateCount,
        AggregationStateHashTable<AggregationStateCount>>(
            accessor,
            group_by_key_ids,
            AggregationStateCount(),
            hash_table);
  } else {
    DCHECK_EQ(1u, argument_ids.size())
        << "Got wrong number of arguments for COUNT: " << argument_ids.size();
    aggregateValueAccessorIntoHashTableUnaryHelper<
        AggregationHandleCount<count_star, nullable_type>,
        AggregationStateCount,
        AggregationStateHashTable<AggregationStateCount>>(
            accessor,
            argument_ids.front(),
            group_by_key_ids,
            AggregationStateCount(),
            hash_table);
  }
}

template <bool count_star, bool nullable_type>
    void AggregationHandleCount<count_star, nullable_type>::mergeStates(
        const AggregationState &source,
        AggregationState *destination) const {
  const AggregationStateCount &count_source = static_cast<const AggregationStateCount&>(source);
  AggregationStateCount *count_destination = static_cast<AggregationStateCount*>(destination);

  count_destination->count_.fetch_add(count_source.count_.load(std::memory_order_relaxed),
                                      std::memory_order_relaxed);
}

template <bool count_star, bool nullable_type>
    ColumnVector* AggregationHandleCount<count_star, nullable_type>::finalizeHashTable(
        const AggregationStateHashTableBase &hash_table,
        std::vector<std::vector<TypedValue>> *group_by_keys) const {
  return finalizeHashTableHelper<AggregationHandleCount<count_star, nullable_type>,
                                 AggregationStateHashTable<AggregationStateCount>>(
      TypeFactory::GetType(kLong),
      hash_table,
      group_by_keys);
}

// Explicitly instantiate and compile in the different versions of
// AggregationHandleCount we need. Note that we do not compile a version with
// 'count_star == true' and 'nullable_type == true', as that combination is
// semantically impossible.
template class AggregationHandleCount<false, false>;
template class AggregationHandleCount<false, true>;
template class AggregationHandleCount<true, false>;

}  // namespace quickstep