/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.

   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/operators/scale_op.h"
#include "paddle/operators/net_op.h"

namespace paddle {
namespace operators {

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

 protected:
  void InferShape(const framework::InferShapeContext &ctx) const override {
    auto *in = ctx.Input<framework::Tensor>("X");
    auto *out = ctx.Output<framework::Tensor>("Out");
    out->Resize(in->dims());
  }
};

template <typename AttrType>
class ScaleOpMaker : public framework::OpProtoAndCheckerMaker {
 public:
  ScaleOpMaker(framework::OpProto *proto, framework::OpAttrChecker *op_checker)
      : OpProtoAndCheckerMaker(proto, op_checker) {
    AddInput("X", "The input tensor of scale operator.").NotInGradient();
    AddOutput("Out", "The output tensor of scale operator.").NotInGradient();
    AddComment(R"DOC(Scale operator

The equation is: Out = scale*X
)DOC");
    AddAttr<AttrType>("scale", "The scaling factor of the scale operator.")
        .SetDefault(1.0);
  }
};

// IdentityOp's gradient is IdentityOp, too.
// Grad(Out=scale(X)) => Grad(X) = scale(Grad(Out))
template <typename AttrType>
class ScaleGradOp : public NetOp {
 public:
  ScaleGradOp(const std::string &type, const framework::VariableNameMap &inputs,
              const framework::VariableNameMap &outputs,
              const framework::AttributeMap &attrs)
      : NetOp(type, inputs, outputs, attrs) {
    AppendOp(framework::OpRegistry::CreateOp(
        "scale", {{"X", {Input(framework::GradVarName("Out"))}}},
        {{"Out", {Output(framework::GradVarName("X"))}}},
        {{"scale", GetAttr<AttrType>("scale")}}));
    CompleteAddOp(false);
  }
};

// IdentityOp is an alias of the ScaleOp. This is also an example for creating
// an alias of an existing operator.
template <typename AttrType>
class IdentityOpMaker : public framework::OpProtoAndCheckerMaker {
 public:
  IdentityOpMaker(framework::OpProto *proto,
                  framework::OpAttrChecker *op_checker)
      : OpProtoAndCheckerMaker(proto, op_checker) {
    AddInput("X", "The input tensor of identity op.");
    AddOutput("Out", "The output tensor of identity op.");
    AddComment(R"DOC(
The identity operator is just an alias of the scale operator with the
attribute scale is fixed to 1.0.
)DOC");
  }
};

template <typename AttrType>
class IdentityOp : public NetOp {
 public:
  IdentityOp(const std::string &type, const framework::VariableNameMap &inputs,
             const framework::VariableNameMap &outputs,
             const framework::AttributeMap &attrs)
      : NetOp(type, inputs, outputs, attrs) {
    AppendOp(framework::OpRegistry::CreateOp(
        "scale", {{"X", {Input("X")}}}, {{"Out", {Output("Out")}}},
        {{"scale", static_cast<AttrType>(1)}}));
  }
};

}  // namespace operators
}  // namespace paddle

namespace ops = paddle::operators;

REGISTER_OP(scale, ops::ScaleOp, ops::ScaleOpMaker<float>, scale_grad,
            ops::ScaleGradOp<float>);
REGISTER_OP_CPU_KERNEL(scale,
                       ops::ScaleKernel<paddle::platform::CPUPlace, float>);
REGISTER_OP_WITHOUT_GRADIENT(identity, ops::IdentityOp<float>,
                             ops::IdentityOpMaker<float>);