// Copyright (c) 2021 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 <memory>
#include <vector>

#include "paddle/fluid/framework/infershape_utils.h"
#include "paddle/fluid/framework/op_registry.h"
#include "paddle/fluid/framework/tensor_util.h"
#include "paddle/phi/core/infermeta_utils.h"
#include "paddle/phi/infermeta/unary.h"

namespace paddle {
namespace operators {

class MatrixPowerOp : public framework::OperatorWithKernel {
 public:
  using framework::OperatorWithKernel::OperatorWithKernel;
};

class MatrixPowerOpMaker : public framework::OpProtoAndCheckerMaker {
 public:
  void Make() override {
    AddInput(
        "X",
        "(Tensor), The input tensor of matrix_power op. Its shape should be "
        "[*, M, M] where * is zero or more batch dimensions, and matrices "
        "on the inner-most 2 dimensions all should be square matrices.");
    AddOutput("Out",
              "(Tensor), The output tensor of matrix_power op. It has the same "
              "shape as the input.");
    AddAttr<int>("n", "(int), The exponent used to calculate the power of X.");
    AddComment(R"DOC(
Matrix Power Operator.

Computes the n-th power of a square matrix or a batch of square matrices.

)DOC");
  }
};

class MatrixPowerOpInferVarType
    : public framework::PassInDtypeAndVarTypeToOutput {
 protected:
  std::unordered_map<std::string, std::string>& GetInputOutputWithSameType()
      const override {
    static std::unordered_map<std::string, std::string> u_map{
        {"X", /*->*/ "Out"}};
    return u_map;
  }
};

class MatrixPowerGradOp : public framework::OperatorWithKernel {
 public:
  using framework::OperatorWithKernel::OperatorWithKernel;

 protected:
  void InferShape(framework::InferShapeContext* context) const override {
    OP_INOUT_CHECK(context->HasInput("X"), "Input", "X", "matrix_power_grad");
    OP_INOUT_CHECK(
        context->HasInput("Out"), "Input", "Out", "matrix_power_grad");
    OP_INOUT_CHECK(context->HasInput(framework::GradVarName("Out")),
                   "Input",
                   "Out@GRAD",
                   "matrix_power_grad");
    auto x_dims = context->GetInputDim("X");
    auto x_grad_name = framework::GradVarName("X");
    if (context->HasOutput(x_grad_name)) {
      context->SetOutputDim(x_grad_name, x_dims);
    }
  }
};

template <typename T>
class MatrixPowerGradOpMaker : public framework::SingleGradOpMaker<T> {
 public:
  using framework::SingleGradOpMaker<T>::SingleGradOpMaker;

 protected:
  void Apply(GradOpPtr<T> op) const override {
    op->SetType(this->ForwardOpType() + "_grad");
    op->SetInput("X", this->Input("X"));
    op->SetInput("Out", this->Output("Out"));
    op->SetInput(framework::GradVarName("Out"), this->OutputGrad("Out"));
    op->SetOutput(framework::GradVarName("X"), this->InputGrad("X"));
    op->SetAttrMap(this->Attrs());
  }
};

}  // namespace operators
}  // namespace paddle

namespace ops = paddle::operators;

DECLARE_INFER_SHAPE_FUNCTOR(matrix_power,
                            MatrixPowerInferShapeFunctor,
                            PD_INFER_META(phi::MatrixPowerInferMeta));

REGISTER_OPERATOR(matrix_power,
                  ops::MatrixPowerOp,
                  ops::MatrixPowerOpMaker,
                  ops::MatrixPowerOpInferVarType,
                  ops::MatrixPowerGradOpMaker<paddle::framework::OpDesc>,
                  ops::MatrixPowerGradOpMaker<paddle::imperative::OpBase>,
                  MatrixPowerInferShapeFunctor);

REGISTER_OPERATOR(matrix_power_grad, ops::MatrixPowerGradOp);