// 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/kernels/scatter_kernel.h"

#include "paddle/phi/backends/gpu/gpu_context.h"
#include "paddle/phi/core/kernel_registry.h"
#include "paddle/phi/core/tensor_utils.h"
#include "paddle/phi/kernels/funcs/scatter.cu.h"

namespace phi {

template <typename T, typename Context>
void ScatterKernel(const Context &dev_ctx,
                   const DenseTensor &x,
                   const DenseTensor &index,
                   const DenseTensor &updates,
                   bool overwrite,
                   DenseTensor *out) {
  if (index.numel() == 0) {
    dev_ctx.template Alloc<T>(out);
    Copy(dev_ctx, x, dev_ctx.GetPlace(), false, out);
    return;
  }
  if (out && out->numel() == 0) {
    dev_ctx.template Alloc<T>(out);
    return;
  }
  Copy(dev_ctx, x, dev_ctx.GetPlace(), false, out);
  // use template class to support int32_t and int64_t
  auto index_type = index.dtype();
  bool index_type_match =
      index_type == DataType::INT32 || index_type == DataType::INT64;
  PADDLE_ENFORCE_EQ(index_type_match,
                    true,
                    common::errors::InvalidArgument(
                        "scatter_op Index holds the wrong type, it holds [%s],"
                        "but desires to be [%s] or [%s].",
                        index_type,
                        DataType::INT32,
                        DataType::INT64));
  if (index_type == DataType::INT32) {
    funcs::GPUScatterAssign<T, int32_t>(
        dev_ctx, updates, index, out, overwrite);
  } else {
    funcs::GPUScatterAssign<T, int64_t>(
        dev_ctx, updates, index, out, overwrite);
  }
}

}  // namespace phi

PD_REGISTER_KERNEL(scatter,
                   GPU,
                   ALL_LAYOUT,
                   phi::ScatterKernel,
                   float,
                   double,
                   int,
                   int64_t,
                   phi::float16,
                   phi::bfloat16) {}