/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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_STORAGE_COMPRESSED_COLUMN_STORE_VALUE_ACCESSOR_HPP_
#define QUICKSTEP_STORAGE_COMPRESSED_COLUMN_STORE_VALUE_ACCESSOR_HPP_

#include <cstddef>
#include <cstdint>
#include <vector>

#include "catalog/CatalogRelationSchema.hpp"
#include "catalog/CatalogTypedefs.hpp"
#include "compression/CompressionDictionaryLite.hpp"
#include "storage/StorageBlockInfo.hpp"
#include "storage/StorageBlockLayout.pb.h"
#include "storage/ValueAccessor.hpp"
#include "types/Type.hpp"
#include "types/TypedValue.hpp"
#include "utility/BitVector.hpp"
#include "utility/Macros.hpp"
#include "utility/PtrMap.hpp"

namespace quickstep {

class CompressedColumnStoreTupleStorageSubBlock;

class CompressedColumnStoreValueAccessorHelper {
 public:
  CompressedColumnStoreValueAccessorHelper(
      const CatalogRelationSchema &relation,
      const tuple_id num_tuples,
      const CompressedBlockInfo &compression_info,
      const std::vector<bool> &dictionary_coded_attributes,
      const std::vector<bool> &truncated_attributes,
      const std::vector<bool> &truncated_attribute_is_int,
      const PtrMap<attribute_id, CompressionDictionaryLite> &dictionaries,
      const std::vector<void*> &column_stripes,
      const PtrVector<BitVector<false>, true> &uncompressed_column_null_bitmaps)
      : relation_(relation),
        num_tuples_(num_tuples),
        compression_info_(compression_info),
        dictionary_coded_attributes_(dictionary_coded_attributes),
        truncated_attributes_(truncated_attributes),
        truncated_attribute_is_int_(truncated_attribute_is_int),
        dictionaries_(dictionaries),
        column_stripes_(column_stripes),
        uncompressed_column_null_bitmaps_(uncompressed_column_null_bitmaps) {
  }

  inline tuple_id numPackedTuples() const {
    return num_tuples_;
  }

  /**
   * @brief Returns whether this accessor has a fast strided ColumnAccessor available
   *        that can be used to optimize memory access in a tight loop iteration
   *        over the underlying storage block.
   *
   * @return true if fast ColumnAccessor is supported, otherwise false.
   */
  inline bool isColumnAccessorSupported() const {
    return false;
  }

  /**
   * @brief Get a pointer to a ColumnAccessor object that provides a fast strided memory
   *        access on the underlying storage block.
   * @note The ownership of the returned object lies with the caller.
   * @warning This method should only be called if isColumnAccessorSupported() method
   *          returned true. If ColumnAccessor is not supported this method will return a nullptr.
   *
   * @param current_tuple_position A constant reference to the tuple position in the containing
   *        ValueAccessor. This reference value is shared between the containing ValueAccessor &
   *        a ColumnAccessor. However, a ColumnAccessor *CANNOT* modify this tuple position.
   * @param attr_id The attribute id on which this ColumnAccessor will be created.
   *
   * @return A pointer to a ColumnAccessor object with specific properties set that can be used
   *         in a tight loop iterations over the underlying storage block.
   **/
  template <bool check_null = true>
  inline const ColumnAccessor<check_null>* getColumnAccessor(const tuple_id &current_tuple_position,
                                                             const attribute_id attr_id) const {
    // Return nullptr because this value accessor does not support column accessor yet.
    return nullptr;
  }

  template <bool check_null>
  inline const void* getAttributeValue(const tuple_id tuple,
                                       const attribute_id attr) const {
    if (dictionary_coded_attributes_[attr]) {
      return dictionaries_.atUnchecked(attr).getUntypedValueForCode<check_null>(
          getCode(tuple, attr));
    } else if (truncated_attributes_[attr]) {
      if (truncated_attribute_is_int_[attr]) {
        int_buffer_ = getCode(tuple, attr);
        return &int_buffer_;
      } else {
        long_buffer_ = getCode(tuple, attr);
        return &long_buffer_;
      }
    } else {
      return getAttributePtr<check_null>(tuple, attr);
    }
  }

  inline TypedValue getAttributeValueTyped(const tuple_id tuple,
                                           const attribute_id attr) const {
    if (dictionary_coded_attributes_[attr]) {
      return dictionaries_.atUnchecked(attr).getTypedValueForCode(
          getCode(tuple, attr));
    } else if (truncated_attributes_[attr]) {
      if (truncated_attribute_is_int_[attr]) {
        return TypedValue(static_cast<int>(getCode(tuple, attr)));
      } else {
        return TypedValue(static_cast<std::int64_t>(getCode(tuple, attr)));
      }
    } else {
      const Type &attr_type = relation_.getAttributeById(attr)->getType();
      const void *untyped_value = getAttributePtr<true>(tuple, attr);
      return (untyped_value == nullptr)
          ? attr_type.makeNullValue()
          : attr_type.makeValue(untyped_value, attr_type.maximumByteLength());
    }
  }

 private:
  template <bool check_null>
  inline const void* getAttributePtr(const tuple_id tid,
                                     const attribute_id attr_id) const {
    if (check_null
        && compression_info_.uncompressed_attribute_has_nulls(attr_id)
        && uncompressed_column_null_bitmaps_[attr_id].getBit(tid)) {
      return nullptr;
    } else {
      return static_cast<const char*>(column_stripes_[attr_id])
             + tid * compression_info_.attribute_size(attr_id);
    }
  }

  inline std::uint32_t getCode(const tuple_id tid,
                               const attribute_id attr_id) const {
    const void *code_location = getAttributePtr<false>(tid, attr_id);
    switch (compression_info_.attribute_size(attr_id)) {
      case 1:
        return *static_cast<const std::uint8_t*>(code_location);
      case 2:
        return *static_cast<const std::uint16_t*>(code_location);
      case 4:
        return *static_cast<const std::uint32_t*>(code_location);
      default:
        FATAL_ERROR("Unexpected byte-length (not 1, 2, or 4) for compressed "
                    "attribute ID " << attr_id
                    << " in CompressedColumnStoreValueAccessorHelper::getCode()");
    }
  }

  const CatalogRelationSchema &relation_;

  const tuple_id num_tuples_;

  const CompressedBlockInfo &compression_info_;
  const std::vector<bool> &dictionary_coded_attributes_;
  const std::vector<bool> &truncated_attributes_;
  const std::vector<bool> &truncated_attribute_is_int_;
  const PtrMap<attribute_id, CompressionDictionaryLite> &dictionaries_;

  const std::vector<void*> &column_stripes_;
  const PtrVector<BitVector<false>, true> &uncompressed_column_null_bitmaps_;

  mutable int int_buffer_;
  mutable std::int64_t long_buffer_;

  DISALLOW_COPY_AND_ASSIGN(CompressedColumnStoreValueAccessorHelper);
};

typedef PackedTupleStorageSubBlockValueAccessor<
    CompressedColumnStoreTupleStorageSubBlock,
    CompressedColumnStoreValueAccessorHelper,
    ValueAccessor::Implementation::kCompressedColumnStore>
        CompressedColumnStoreValueAccessor;

}  // namespace quickstep

#endif  // QUICKSTEP_STORAGE_COMPRESSED_COLUMN_STORE_VALUE_ACCESSOR_HPP_