// Copyright (c) 2020 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.

#ifdef PADDLE_WITH_XPU

#include <memory>
#include <string>
#include <vector>

#include "paddle/fluid/operators/reduce_ops/reduce_mean_op.h"

namespace paddle {
namespace operators {
template <typename DeviceContext, typename T>
class ReduceMeanXPUKernel : public framework::OpKernel<T> {
  using XPUType = typename XPUTypeTrait<T>::Type;

 public:
  void Compute(const framework::ExecutionContext& context) const override {
    PADDLE_ENFORCE_EQ(
        platform::is_xpu_place(context.GetPlace()),
        true,
        platform::errors::Unavailable("This kernel only runs on XPU."));
    bool reduce_all = context.Attr<bool>("reduce_all");
    auto* input = context.Input<Tensor>("X");
    auto* output = context.Output<Tensor>("Out");
    output->mutable_data<T>(context.GetPlace());
    auto& dev_ctx = context.template device_context<DeviceContext>();

    std::vector<int> xdims;
    for (int i = 0; i < input->dims().size(); i++) {
      xdims.push_back(input->dims()[i]);
    }
    auto rdims = context.Attr<std::vector<int>>("dim");
    const auto& input_dim_size = input->dims().size();
    std::vector<int> reduce_dims;
    if (reduce_all) {
      for (size_t i = 0; i < xdims.size(); i++) {
        reduce_dims.push_back(static_cast<int>(i));
      }
    } else {
      for (size_t i = 0; i < rdims.size(); ++i) {
        if (rdims[i] < 0) {
          reduce_dims.push_back(rdims[i] + input_dim_size);
        } else {
          reduce_dims.push_back(rdims[i]);
        }
      }
    }
    int r = xpu::reduce_mean(dev_ctx.x_context(),
                             reinterpret_cast<const XPUType*>(input->data<T>()),
                             reinterpret_cast<XPUType*>(output->data<T>()),
                             xdims,
                             reduce_dims);

    PADDLE_ENFORCE_EQ(r,
                      XPU_SUCCESS,
                      platform::errors::External(
                          "XPU reduce_mean kernel return wrong value[%d %s]",
                          r,
                          XPUAPIErrorMsg[r]));
  }
};

template <typename DeviceContext, typename T>
class ReduceMeanGradXPUKernel : public framework::OpKernel<T> {
  using XPUType = typename XPUTypeTrait<T>::Type;

 public:
  void Compute(const framework::ExecutionContext& ctx) const override {
    auto* input = ctx.Input<Tensor>("X");
    auto* output_grad = ctx.Input<Tensor>(framework::GradVarName("Out"));
    auto* input_grad = ctx.Output<Tensor>(framework::GradVarName("X"));

    XPUType* x_data =
        reinterpret_cast<XPUType*>(input_grad->mutable_data<T>(ctx.GetPlace()));
    const XPUType* dy_data =
        reinterpret_cast<const XPUType*>(output_grad->data<T>());

    bool reduce_all = ctx.Attr<bool>("reduce_all");
    auto reduce_dims = ctx.Attr<std::vector<int>>("dim");

    std::vector<int> xdims;
    for (int i = 0; i < input->dims().size(); i++) {
      xdims.push_back(input->dims()[i]);
    }
    std::vector<int> ydims;
    for (int i = 0; i < output_grad->dims().size(); i++) {
      ydims.push_back(output_grad->dims()[i]);
    }

    int reduce_numel = 1;
    if (reduce_all) {
      reduce_dims.clear();
      for (size_t d = 0; d < xdims.size(); ++d) {
        reduce_dims.push_back(static_cast<int>(d));
      }
    }
    for (auto& d : reduce_dims) {
      if (d < 0) {
        d = d + xdims.size();
      }
      reduce_numel *= xdims[d];
    }

    float val = 1.0f / static_cast<float>(reduce_numel);

    auto& dev_ctx = ctx.template device_context<DeviceContext>();

    int r = xpu::constant(
        dev_ctx.x_context(), x_data, input->numel(), static_cast<XPUType>(val));

    PADDLE_ENFORCE_EQ(r,
                      XPU_SUCCESS,
                      platform::errors::External(
                          "XPU constant kernel return wrong value[%d %s]",
                          r,
                          XPUAPIErrorMsg[r]));
    r = xpu::broadcast_mul(
        dev_ctx.x_context(), x_data, dy_data, x_data, xdims, ydims);

    PADDLE_ENFORCE_EQ(r,
                      XPU_SUCCESS,
                      platform::errors::External(
                          "XPU broadcast_mul kernel return wrong value[%d %s]",
                          r,
                          XPUAPIErrorMsg[r]));
  }
};

}  // namespace operators
}  // namespace paddle

REGISTER_OP_XPU_KERNEL(
    reduce_mean,
    ops::ReduceMeanXPUKernel<paddle::platform::XPUDeviceContext, float>);

REGISTER_OP_XPU_KERNEL(
    reduce_mean_grad,
    ops::ReduceMeanGradXPUKernel<paddle::platform::XPUDeviceContext, float>);

#endif
