// Copyright (c) 2024 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/flatten_kernel.h"

#include "paddle/phi/backends/onednn/onednn_reuse.h"
#include "paddle/phi/core/kernel_registry.h"

namespace phi {

template <typename T, typename Context>
void ExecuteFlatten(const Context& dev_ctx,
                    const DenseTensor& x,
                    const DDim& x_dims,
                    const DDim& out_dims,
                    DenseTensor* out) {
  auto x_vec_dims = vectorize(x_dims);

  funcs::ReorderOneDNNHandler reorder_handler(
      x_vec_dims,
      x.dtype(),
      funcs::ToOneDNNDataType(x.dtype()),
      dev_ctx.GetEngine());

  auto reorder_src_memory_p = reorder_handler.AcquireSrcMemory(
      x.mem_desc(), funcs::to_void_cast(x.data<T>()));
  out->Resize(x_dims);  // to match x numel, format is changed later
  // reorder is done into a plain tag to allow usage with blocked formats
  auto reorder_dst_memory_p = reorder_handler.AcquireDstMemory(
      out, funcs::GetPlainOneDNNFormat(x_dims.size()), dev_ctx.GetPlace());
  auto reorder_p = reorder_handler.AcquireReorder(reorder_dst_memory_p,
                                                  reorder_src_memory_p);
  auto& astream = OneDNNContext::tls().get_stream();
  reorder_p->execute(astream, *reorder_src_memory_p, *reorder_dst_memory_p);
  astream.wait();

  out->Resize(out_dims);

  auto reshape_dims =
      out_dims.size() != 0 ? vectorize(out_dims) : std::vector<int64_t>{1};
  out->set_mem_desc(reorder_dst_memory_p->get_desc().reshape(reshape_dims));
}

template <typename T, typename Context>
void FlattenKernel(const Context& dev_ctx,
                   const DenseTensor& x,
                   int start_axis,
                   int stop_axis,
                   DenseTensor* out) {
  auto x_dims = x.dims();
  auto out_dims = out->dims();
  ExecuteFlatten<T, Context>(dev_ctx, x, x_dims, out_dims, out);
}

template <typename T, typename Context>
void FlattenWithXShapeKernel(const Context& dev_ctx,
                             const DenseTensor& x,
                             int start_axis,
                             int stop_axis,
                             DenseTensor* out,
                             DenseTensor* xshape UNUSED) {
  FlattenKernel<T, Context>(dev_ctx, x, start_axis, stop_axis, out);
}

}  // namespace phi
PD_REGISTER_KERNEL(
    flatten, OneDNN, ONEDNN, phi::FlattenKernel, float, phi::bfloat16) {}

PD_REGISTER_KERNEL(flatten_with_xshape,
                   OneDNN,
                   ONEDNN,
                   phi::FlattenWithXShapeKernel,
                   float,
                   phi::bfloat16) {}