/**
 * Copyright 2019 Huawei Technologies Co., Ltd
 *
 * 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 DATASET_ENGINE_DATA_BUFFER_H_
#define DATASET_ENGINE_DATA_BUFFER_H_

#include <iostream>
#include <map>
#include <memory>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
#include "dataset/util/allocator.h"
#include "dataset/util/status.h"
#include "dataset/core/constants.h"
#include "dataset/core/tensor.h"

namespace mindspore {
namespace dataset {
// Forward declares
class StorageClient;

// The DataBuffer class is a base class that will represent the data for n values based
// on a unique row id for each row of data.
// There can be different types of DataBuffers to abstract over how the data is stored
// in memory and acquired from storage.
// Each buffer holds a range of consecutive row id's.
class DataBuffer {
 public:
  // Buffer flags
  enum BufferFlags : uint32_t {
    kDeBFlagNone = 0,
    kDeBFlagEOF = 1,       // The buffer is an eof end-of-data msg
    kDeBFlagEOE = 1u << 1  // The buffer is an eoe end-of-epoch msg
  };

  // Name: Constructor #1
  // Description: This is the main constructor that is used for making a buffer
  DataBuffer(int32_t id, BufferFlags flags);

  // Destructor
  virtual ~DataBuffer();

  // Name: CreateDataBuffer()
  // Description: A factory method to create the appropriate type of derived class
  //              buffer.  Returns the base class reference for DataBuffer.
  static Status CreateDataBuffer(
    int32_t id,                      // In: The id for the new buffer
    std::shared_ptr<StorageClient>,  // In: The StorageClient is used to choose the buffer type to create
    std::unique_ptr<DataBuffer> *);

  // Name: print()
  // Description: A function that prints info about the DataBuffer (base class version)
  virtual void Print(std::ostream &out,     // In: The output stream to print to
                     bool show_all) const;  // In: T/F if it should show everything

  // Provide stream operator for displaying it
  friend std::ostream &operator<<(std::ostream &out, const DataBuffer &cb) {
    cb.Print(out, false);
    return out;
  }

  // Name: load()
  // Description: populates the DataBuffer with data based on it's id
  virtual Status Load();

  // Convenience getter functions for flag checking
  bool eof() const { return (static_cast<uint32_t>(buffer_flags_) & static_cast<uint32_t>(kDeBFlagEOF)); }

  bool eoe() const { return (static_cast<uint32_t>(buffer_flags_) & static_cast<uint32_t>(kDeBFlagEOE)); }

  // Simple getter funcs
  int32_t id() const { return buffer_id_; }

  void set_id(int32_t id) { buffer_id_ = id; }

  int32_t NumRows() const { return ((tensor_table_) ? tensor_table_->size() : 0); }

  int32_t NumCols() const {
    return (tensor_table_ == nullptr || tensor_table_->empty()) ? 0 : tensor_table_->at(0).size();
  }

  BufferFlags buffer_flags() const { return buffer_flags_; }

  // Remove me!! Callers should fetch rows via pop
  Status GetTensor(std::shared_ptr<Tensor> *, int32_t row_id, int32_t col_id) const;

  // Remove me!! Callers should drain rows via pop.
  Status GetRow(int32_t row_id, TensorRow *) const;

  // Get a row from the TensorTable
  Status PopRow(TensorRow *);

  Status SliceOff(int64_t number_of_rows);

  // Return a mapping from col names to col id.
  std::unordered_map<std::string, int32_t> column_name_map() const { return column_name_map_; }

  // Update the column name to index mapping.
  void set_column_name_map(const std::unordered_map<std::string, int32_t> &new_col_name_map) {
    column_name_map_ = new_col_name_map;
  }

  // Replacing mTensorTable, the unique_ptr assignment will release the old TensorTable.
  void set_tensor_table(std::unique_ptr<TensorQTable> new_table) { tensor_table_ = std::move(new_table); }

  void set_flag(BufferFlags in_flag) {
    buffer_flags_ = static_cast<BufferFlags>(static_cast<uint32_t>(buffer_flags_) | static_cast<uint32_t>(in_flag));
  }

  void Shuffle() {}  // does nothing right now.  possibly remove later

  // *****  column_name_map_ manipulation methods  *****

  // Append Column to mColumnNameMap
  Status AppendColumn(const std::string &name, const int32_t &old_id) const {  // does nothing right now
    return Status::OK();
  }

 protected:
  int32_t buffer_id_;                                         // An id for the buffer.
  std::unique_ptr<TensorQTable> tensor_table_;                // A table (row major) of Tensors
  BufferFlags buffer_flags_;                                  // bit mask for various buffer properties
  std::unordered_map<std::string, int32_t> column_name_map_;  // A mapping between column index to column name.
};
}  // namespace dataset
}  // namespace mindspore

#endif  // DATASET_ENGINE_DATA_BUFFER_H_
