/* Copyright (c) 2022 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. */

#include "paddle/phi/api/lib/data_transform.h"

#include "paddle/phi/api/lib/kernel_dispatch.h"
#include "paddle/phi/api/lib/utils/allocator.h"
#include "paddle/phi/backends/all_context.h"
#include "paddle/phi/core/kernel_registry.h"
#include "paddle/phi/kernels/cast_kernel.h"
#include "paddle/phi/kernels/copy_kernel.h"
#include "paddle/phi/kernels/transfer_layout_kernel.h"

#include "paddle/fluid/framework/tensor_util.h"

namespace paddle {
namespace experimental {

inline bool NeedTransformDataType(const DataType& input,
                                  const DataType& target,
                                  const TransformFlag& transform_flag) {
  return input != target &&
         (transform_flag.need_trans_data_type() ||
          target == DataType::COMPLEX64 || target == DataType::COMPLEX128);
}

inline bool NeedTransformPlace(const paddle::platform::Place& input,
                               const Backend& target,
                               const TransformFlag& transform_flag) {
  // NOTE(dev): The default value of TransformFlag is True, if it is set with
  // False
  // somewhere such as api.yaml or backward.yaml that means we should skip data
  // transform. Because "stop_transform_" has highest priority.
  if (!transform_flag.need_trans_backend()) {
    return false;
  }
  bool ret = input.GetType() == AllocationType::GPUPINNED ||
             (target != Backend::ALL_BACKEND &&
              phi::TransToPhiBackend(input) !=
                  (target != Backend::GPUDNN ? target : Backend::GPU));
  return ret;
}

inline bool NeedTransformLayout(const DataLayout& input,
                                const DataLayout& target,
                                const TransformFlag& transform_flag) {
  bool ret = transform_flag.need_trans_layout() &&
             (input != DataLayout::ALL_LAYOUT &&
              target != DataLayout::ALL_LAYOUT && input != target);
  return ret;
}

inline phi::DenseTensor TransDataLayout(const phi::DenseTensor& tensor,
                                        DataLayout layout) {
  auto& pool = paddle::platform::DeviceContextPool::Instance();
  VLOG(3) << "DataLayoutTransform src_layout: " << tensor.layout()
          << " dst_layout: " << layout;
  if (platform::is_cpu_place(tensor.place())) {
    auto* dev_ctx = static_cast<phi::CPUContext*>(pool.Get(tensor.place()));
    return phi::TransferLayout(*dev_ctx, tensor, layout);
  } else {
    PADDLE_THROW(phi::errors::PreconditionNotMet(
        "Unsupported data layout cast from CPU to GPU."));
  }
}

template <typename Context>
phi::DenseTensor CastDateType(const Context& dev_ctx,
                              const phi::DenseTensor& tensor,
                              DataType dtype) {
  switch (tensor.dtype()) {
    case DataType::FLOAT32:
      return phi::Cast<float>(dev_ctx, tensor, dtype);
    case DataType::FLOAT64:
      return phi::Cast<double>(dev_ctx, tensor, dtype);
    case DataType::INT32:
      return phi::Cast<int32_t>(dev_ctx, tensor, dtype);
    case DataType::INT64:
      return phi::Cast<int64_t>(dev_ctx, tensor, dtype);
    case DataType::FLOAT16:
      return phi::Cast<phi::dtype::float16>(dev_ctx, tensor, dtype);
    case DataType::BFLOAT16:
      return phi::Cast<phi::dtype::bfloat16>(dev_ctx, tensor, dtype);
    case DataType::BOOL:
      return phi::Cast<bool>(dev_ctx, tensor, dtype);
    case DataType::INT16:
      return phi::Cast<int16_t>(dev_ctx, tensor, dtype);
    case DataType::UINT8:
      return phi::Cast<uint8_t>(dev_ctx, tensor, dtype);
    default:
      PADDLE_THROW(phi::errors::Unimplemented(
          "Data type (%s) is not supported when casting data type.",
          tensor.dtype()));
  }
}

#if defined(PADDLE_WITH_CUDA) || defined(PADDLE_WITH_HIP)
phi::DenseTensor CastDateType(const phi::GPUContext& dev_ctx,
                              const phi::DenseTensor& tensor,
                              DataType dtype) {
  switch (tensor.dtype()) {
    case DataType::FLOAT32:
      return phi::Cast<float>(dev_ctx, tensor, dtype);
    case DataType::FLOAT64:
      return phi::Cast<double>(dev_ctx, tensor, dtype);
    case DataType::INT32:
      return phi::Cast<int32_t>(dev_ctx, tensor, dtype);
    case DataType::INT64:
      return phi::Cast<int64_t>(dev_ctx, tensor, dtype);
    case DataType::FLOAT16:
      return phi::Cast<phi::dtype::float16>(dev_ctx, tensor, dtype);
    case DataType::BOOL:
      return phi::Cast<bool>(dev_ctx, tensor, dtype);
    case DataType::INT16:
      return phi::Cast<int16_t>(dev_ctx, tensor, dtype);
    case DataType::UINT8:
      return phi::Cast<uint8_t>(dev_ctx, tensor, dtype);
    default:
      PADDLE_THROW(phi::errors::Unimplemented(
          "Data type (%s) is not supported when casting data type.",
          tensor.dtype()));
  }
}
#endif

inline phi::DenseTensor TransDataType(const phi::DenseTensor& tensor,
                                      DataType dtype) {
  auto& pool = paddle::platform::DeviceContextPool::Instance();

  VLOG(3) << "DataTypeTransform src_dtype: " << tensor.dtype()
          << " dst_dtype: " << dtype;

  DefaultAllocator alloc(tensor.place());
  phi::DenseTensor out(&alloc, {dtype, tensor.dims(), tensor.layout()});

  if (platform::is_cpu_place(tensor.place())) {
    auto* dev_ctx = static_cast<phi::CPUContext*>(pool.Get(tensor.place()));
    return CastDateType(*dev_ctx, tensor, dtype);
#if defined(PADDLE_WITH_CUDA) || defined(PADDLE_WITH_HIP)
  } else if (platform::is_gpu_place(tensor.place())) {
    auto* dev_ctx = static_cast<phi::GPUContext*>(pool.Get(tensor.place()));
    return CastDateType(*dev_ctx, tensor, dtype);
#endif
  } else {
    PADDLE_THROW(phi::errors::Unimplemented(
        "Place type is not supported when casting data type."));
  }
  return out;
}

inline phi::DenseTensor TransDataPlace(const phi::DenseTensor& tensor,
                                       Place dst_place) {
  VLOG(3) << "DeviceTransform in, src_place " << tensor.place()
          << " dst_place: " << dst_place;

  DefaultAllocator alloc(dst_place);
  phi::DenseTensor out(&alloc,
                       {tensor.dtype(), tensor.dims(), tensor.layout()});

#if defined(PADDLE_WITH_CUDA) || defined(PADDLE_WITH_HIP)
  auto& pool = paddle::platform::DeviceContextPool::Instance();
  // NOTE(yy): TransDataPlace should wait for computation of input.
  if (!platform::is_cuda_pinned_place(tensor.place())) {
    pool.Get(tensor.place())->Wait();
    pool.Get(dst_place)->Wait();
  }
#endif

  // FIXME(zcd): TransDataPlace is used to transform data from GPU to CPU and
  // the enforced checkings have been done in GetDeviceContext, so the
  // `dev_ctx->Wait()` is necessary. But `dev_ctx->Wait()` will make the program
  // slow, especially when the number of elements is little, for example,
  // the elements of learning rate are one and it's CPU side.
  // One solution is to use a CUDA kernel to complete the copy operation when
  // the transforming is from CPU to GPU and the number of elements is little.
  // But the embarrassment is that this solution this solution makes training
  // slower.
  paddle::framework::TensorCopySync(tensor, dst_place, &out);
  return out;
}

phi::DenseTensor TransformData(phi::DenseTensor* tensor,
                               const phi::TensorArgDef& target_args_def,
                               const TransformFlag& transform_flag) {
  phi::DenseTensor out = *tensor;
  bool trans_layout = false;
  bool trans_dtype = false;
  if (NeedTransformLayout(
          tensor->layout(), target_args_def.layout, transform_flag)) {
    out = TransDataLayout(out, target_args_def.layout);
    trans_layout = true;
  }

  if (NeedTransformDataType(
          tensor->dtype(), target_args_def.dtype, transform_flag)) {
    out = TransDataType(out, target_args_def.dtype);
    trans_dtype = true;
  }

  if (NeedTransformPlace(
          out.place(), target_args_def.backend, transform_flag)) {
    out = TransDataPlace(out, phi::TransToPhiPlace(target_args_def.backend));
    if (!trans_layout && !trans_dtype &&
        tensor->place().GetType() == AllocationType::GPUPINNED) {
      tensor->ShareBufferWith(out);
    }
  }
  return out;
}

std::shared_ptr<phi::DenseTensor> PrepareData(
    const Tensor& input,
    const phi::TensorArgDef& target_args_def,
    const TransformFlag& transform_flag) {
  const auto& tensor_in = input.impl();
  if (tensor_in) {
    phi::DenseTensor& dense_tensor =
        *static_cast<phi::DenseTensor*>(tensor_in.get());
    if (!transform_flag.NeedTransform() || !dense_tensor.initialized() ||
        (!NeedTransformPlace(
             dense_tensor.place(), target_args_def.backend, transform_flag) &&
         !NeedTransformDataType(
             dense_tensor.dtype(), target_args_def.dtype, transform_flag) &&
         !NeedTransformLayout(
             dense_tensor.layout(), target_args_def.layout, transform_flag))) {
      return std::static_pointer_cast<phi::DenseTensor>(tensor_in);
    }
    phi::DenseTensor out =
        TransformData(&dense_tensor, target_args_def, transform_flag);
    return std::make_shared<phi::DenseTensor>(std::move(out));
  }
  return nullptr;
}

paddle::optional<phi::DenseTensor> PrepareData(
    const paddle::optional<Tensor>& input,
    const phi::TensorArgDef& target_args_def,
    const TransformFlag& transform_flag) {
  if (input) {
    return {*PrepareData(*input, target_args_def, transform_flag)};
  }
  return paddle::none;
}

std::unique_ptr<std::vector<phi::DenseTensor>> PrepareData(
    const std::vector<Tensor>& inputs,
    const phi::TensorArgDef& target_args_def,
    const TransformFlag& transform_flag) {
  auto pt_tensors = std::make_unique<std::vector<phi::DenseTensor>>();
  pt_tensors->reserve(inputs.size());

  for (const auto& input : inputs) {
    const auto& tensor_in = input.impl();
    if (!transform_flag.NeedTransform() || !tensor_in->initialized() ||
        (!NeedTransformPlace(
             tensor_in->place(), target_args_def.backend, transform_flag) &&
         !NeedTransformDataType(
             tensor_in->dtype(), target_args_def.dtype, transform_flag) &&
         !NeedTransformLayout(
             tensor_in->layout(), target_args_def.layout, transform_flag))) {
      pt_tensors->emplace_back(
          *std::dynamic_pointer_cast<phi::DenseTensor>(tensor_in));
    } else {
      pt_tensors->emplace_back(
          TransformData((static_cast<phi::DenseTensor*>(tensor_in.get())),
                        target_args_def,
                        transform_flag));
    }
  }

  return pt_tensors;
}

}  // namespace experimental
}  // namespace paddle