/* Copyright (c) 2016 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/fluid/framework/data_layout_transform.h"
#include "paddle/fluid/framework/feed_fetch_type.h"
#include "paddle/fluid/framework/op_registry.h"
#include "paddle/fluid/platform/device_context.h"
#include "paddle/fluid/platform/profiler.h"

namespace paddle {
namespace operators {

class FetchOp : public framework::OperatorBase {
 public:
  FetchOp(const std::string &type, const framework::VariableNameMap &inputs,
          const framework::VariableNameMap &outputs,
          const framework::AttributeMap &attrs)
      : OperatorBase(type, inputs, outputs, attrs) {}

 private:
  void RunImpl(const framework::Scope &scope,
               const platform::Place &place) const override {
    auto fetch_var_name = Input("X");
    auto *fetch_var = scope.FindVar(fetch_var_name);
    PADDLE_ENFORCE(fetch_var != nullptr,
                   "Cannot find the fetch variable(%s) in scope.\n"
                   "Confirm that you have used the fetch `Variable` format "
                   "instead of the string literal('%s') in `fetch_list` "
                   "parameter when using `executor.run` method. In other "
                   "words, the format of "
                   "`executor.run(fetch_list=[fetch_var])`(fetch_var is a "
                   "Variable) is recommended.",
                   fetch_var_name, fetch_var_name);

    auto out_name = this->Output("Out");
    auto *out_var = scope.FindVar(out_name);
    PADDLE_ENFORCE(out_var != nullptr,
                   "Cannot find out_var in scope, out_var_name is %s.",
                   out_name);

    auto col = static_cast<size_t>(Attr<int>("col"));

    auto *fetch_list = out_var->GetMutable<framework::FeedFetchList>();
    auto &src_item = fetch_var->Get<framework::FeedFetchType>();

    if (col >= fetch_list->size()) {
      fetch_list->resize(col + 1);
    }
    auto &dst_item = fetch_list->at(col);

    // FIXME(yuyang18): Should we assume the fetch operator always generate
    // CPU outputs?
    if (src_item.IsInitialized() && src_item.numel() > 0) {
#ifdef PADDLE_WITH_MKLDNN
      // Conversion from MKL-DNN to Paddle
      if (src_item.layout() == framework::DataLayout::kMKLDNN) {
        framework::Tensor out;
        // Convert to desired Paddle layout, apart from grads of filter
        // as params are not a subject to paddle's data_format
        framework::innerTransDataLayoutFromMKLDNN(
            src_item.layout(),
            fetch_var_name == framework::GradVarName("Filter")
                ? framework::DataLayout::kNCHW
                : paddle::platform::get_cur_paddle_data_layout(),
            src_item, &out, platform::CPUPlace());
        TensorCopySync(out, platform::CPUPlace(), &dst_item);
      } else {
        TensorCopySync(src_item, platform::CPUPlace(), &dst_item);
      }
#else
      TensorCopySync(src_item, platform::CPUPlace(), &dst_item);
#endif
    } else {
      // Not copy, if the src tensor is empty.
      dst_item.clear();
      dst_item.Resize({0});
    }
    dst_item.set_lod(src_item.lod());

    VLOG(3) << "Fetch variable " << fetch_var_name << " to " << out_name;
  }
};

class FetchOpInfoMaker : public framework::OpProtoAndCheckerMaker {
 public:
  void Make() override {
    AddInput("X", "The input of fetch op");
    AddOutput("Out", "The output of fetch op");
    AddAttr<int>("col", "(int) The column of fetch");
    AddComment(R"DOC(
Fetch Operator.

It should not be configured by users directly.

)DOC");
  }
};
}  // namespace operators
}  // namespace paddle

REGISTER_OPERATOR(
    fetch, paddle::operators::FetchOp,
    paddle::framework::EmptyGradOpMaker<paddle::framework::OpDesc>,
    paddle::framework::EmptyGradOpMaker<paddle::imperative::OpBase>,
    paddle::operators::FetchOpInfoMaker);