//   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
//
// 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.

#pragma once

#include "paddle/fluid/framework/op_registry.h"
#include "paddle/fluid/framework/reader.h"

namespace paddle {
namespace operators {
namespace reader {

static constexpr char kFileFormatSeparator[] = ":";

using FileReaderCreator = std::function<framework::ReaderBase*(
    const std::string&, const std::vector<framework::DDim>&)>;

std::unordered_map<std::string, FileReaderCreator>& FileReaderRegistry();

template <typename Reader>
int RegisterFileReader(const std::string& filetype) {
  FileReaderRegistry()[filetype] = [](
      const std::string& fn, const std::vector<framework::DDim>& dims) {
    return new Reader(fn, dims);
  };
  return 0;
}

std::unique_ptr<framework::ReaderBase> CreateReaderByFileName(
    const std::string& file_name, const std::vector<framework::DDim>& dims) {
  size_t separator_pos = file_name.find(kFileFormatSeparator);
  PADDLE_ENFORCE_NE(separator_pos, std::string::npos,
                    "File name illegal! A legal file name should be like: "
                    "[file_format]:[file_name] (e.g., 'recordio:data_file').");
  std::string filetype = file_name.substr(0, separator_pos);
  std::string f_name = file_name.substr(separator_pos + 1);

  auto itor = FileReaderRegistry().find(filetype);
  PADDLE_ENFORCE(itor != FileReaderRegistry().end(),
                 "No file reader registered for '%s' format.", filetype);
  framework::ReaderBase* reader = (itor->second)(f_name, dims);
  return std::unique_ptr<framework::ReaderBase>(reader);
}

extern std::vector<framework::DDim> RestoreShapes(
    const std::vector<int>& shape_concat, const std::vector<int>& ranks);

class FileReaderMakerBase : public framework::OpProtoAndCheckerMaker {
 public:
  FileReaderMakerBase(OpProto* op_proto, OpAttrChecker* op_checker);
};

class FileReaderInferShape : public framework::InferShapeBase {
 public:
  void operator()(framework::InferShapeContext* ctx) const override;
};

class FileReaderInferVarType : public framework::VarTypeInference {
 public:
  void operator()(const framework::OpDesc& op_desc,
                  framework::BlockDesc* block) const override;
};

// general infershape for decorated reader
class DecoratedReaderInferShape : public framework::InferShapeBase {
 public:
  void operator()(framework::InferShapeContext* ctx) const override;
};

// general var type inference for decorated reader
class DecoratedReaderInferVarType : public framework::VarTypeInference {
 public:
  void operator()(const framework::OpDesc& op_desc,
                  framework::BlockDesc* block) const override;
};

class DecoratedReaderMakerBase : public framework::OpProtoAndCheckerMaker {
 public:
  DecoratedReaderMakerBase(OpProto* op_proto, OpAttrChecker* op_checker);
};

}  // namespace reader
}  // namespace operators
}  // namespace paddle

#define REGISTER_FILE_READER_OPERATOR(op_name, ...)                  \
  REGISTER_OPERATOR(op_name, __VA_ARGS__,                            \
                    paddle::operators::reader::FileReaderInferShape, \
                    paddle::framework::EmptyGradOpMaker,             \
                    paddle::operators::reader::FileReaderInferVarType)

#define REGISTER_DECORATED_READER_OPERATOR(op_name, ...)                  \
  REGISTER_OPERATOR(op_name, __VA_ARGS__,                                 \
                    paddle::operators::reader::DecoratedReaderInferShape, \
                    paddle::framework::EmptyGradOpMaker,                  \
                    paddle::operators::reader::DecoratedReaderInferVarType)

#define REGISTER_FILE_READER(_filetype, _reader)            \
  STATIC_ASSERT_GLOBAL_NAMESPACE(                           \
      _reg_file_reader_##_filetype,                         \
      "Must use REGISTER_FILE_READER in global namespace"); \
  int TouchFileReader##_filetype() { return 0; }            \
  int _reg_file_reader_entry_##filetype =                   \
      paddle::operators::reader::RegisterFileReader<_reader>(#_filetype)

#define USE_FILE_READER(filetype)         \
  extern int TouchFileReader##filetype(); \
  static int _use_##filetype = TouchFileReader##filetype()