/* 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/operators/distributed_ops/lookup_sparse_table_fuse_adam_op.h"

#include <string>
namespace paddle {
namespace operators {

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

  void InferShape(framework::InferShapeContext *ctx) const override {
    PADDLE_ENFORCE(ctx->HasInput("Grad"),
                   "Input(Grad) of LargeScaleFuseAdamOp should not be null.");
    PADDLE_ENFORCE(
        ctx->HasInput("LearningRate"),
        "Input(LearningRate) of LargeScaleFuseAdamOp should not be null.");

    auto lr_dims = ctx->GetInputDim("LearningRate");

    PADDLE_ENFORCE_NE(framework::product(lr_dims), 0,
                      "Maybe the Input variable LearningRate has not "
                      "been initialized. You may need to confirm "
                      "if you put exe.run(startup_program) "
                      "after optimizer.minimize function.");

    PADDLE_ENFORCE_EQ(framework::product(lr_dims), 1,
                      "Learning rate should have 1 element");
  }

 protected:
  framework::OpKernelType GetExpectedKernelType(
      const framework::ExecutionContext &ctx) const override {
    auto data_type = OperatorWithKernel::IndicateVarDataType(ctx, "Grad");
    return framework::OpKernelType(data_type, ctx.device_context());
  }

  framework::OpKernelType GetKernelTypeForVar(
      const std::string &var_name, const framework::Tensor &tensor,
      const framework::OpKernelType &expected_kernel_type) const {
    if (var_name == "LearningRate") {
      return framework::OpKernelType(tensor.type(), tensor.place(),
                                     tensor.layout());
    }
    return framework::OpKernelType(expected_kernel_type.data_type_,
                                   tensor.place(), tensor.layout());
  }
};

class LargeScaleFuseAdamOpInferVarType : public framework::VarTypeInference {
 public:
  void operator()(framework::InferVarTypeContext *ctx) const override {
    auto in_var_type = ctx->GetInputType("Grad");
    PADDLE_ENFORCE_EQ(in_var_type == framework::proto::VarType::SELECTED_ROWS ||
                          in_var_type == framework::proto::VarType::LOD_TENSOR,
                      true, platform::errors::InvalidArgument(
                                "The input Var's type should be LoDtensor or "
                                "SelectedRows, but the received type is %s",
                                in_var_type));
  }
};

class LargeScaleFuseAdamOpMaker : public framework::OpProtoAndCheckerMaker {
 public:
  void Make() override {
    AddInput("Grad",
             "(SelectedRows) Ids's type should be SelectedRows"
             "THe ids to be looked up in W.");

    AddInput("Beta1Pow", "(Tensor) Input beta1 power accumulator");
    AddInput("Beta2Pow", "(Tensor) Input beta2 power accumulator");
    AddInput("LearningRate", "(Tensor) Learning rate of SGD");
    AddOutput("Beta1PowOut", "(Tensor) Output beta1 power accumulator");
    AddOutput("Beta2PowOut", "(Tensor) Output beta2 power accumulator");

    AddAttr<float>("beta1",
                   "(float, default 0.9) "
                   "Exponential decay rate for the "
                   "first moment estimates.")
        .SetDefault(0.9f);

    AddAttr<float>("beta2",
                   "(float, default 0.999) "
                   "exponential decay rate for the "
                   "second moment estimates.")
        .SetDefault(0.999f);

    AddAttr<float>("epsilon",
                   "(float, default 1.0e-8) "
                   "Constant for numerical stability")
        .SetDefault(1.0e-8f);

    AddAttr<bool>("is_entry",
                  "(bool)"
                  "sparse table need entry");

    AddAttr<std::string>("tablename",
                         "(string)"
                         "sparse table name");

    AddAttr<std::vector<std::string>>("value_names",
                                      "(strings)"
                                      "sparse table name");

    AddComment(R"DOC(
Adam Optimizer.

This implements the Adam optimizer from Section 2 of the Adam
paper : https://arxiv.org/abs/1412.6980.
Adam is a first-order gradient-based optimization method based on
adaptive estimates of lower-order moments.

Adam updates:

$$
moment\_1\_out = \beta_1 * moment\_1 + (1 - \beta_1) * grad \\
moment\_2_\out = \beta_2 * moment\_2 + (1 - \beta_2) * grad * grad \\
learning\_rate = learning\_rate *
                  \frac{\sqrt{1 - \beta_{2\_pow}}}{1 - \beta_{1\_pow}} \\
param\_out = param - learning\_rate * \frac{moment\_1}{\sqrt{moment\_2} + \epsilon}
$$

)DOC");
  }
};

}  // namespace operators
}  // namespace paddle

namespace ops = paddle::operators;
REGISTER_OPERATOR(
    lookup_sparse_table_fuse_adam, ops::LargeScaleFuseAdamOp,
    ops::LargeScaleFuseAdamOpMaker,
    paddle::framework::EmptyGradOpMaker<paddle::framework::OpDesc>,
    paddle::framework::EmptyGradOpMaker<paddle::imperative::OpBase>,
    ops::LargeScaleFuseAdamOpInferVarType);

REGISTER_OP_CPU_KERNEL(
    lookup_sparse_table_fuse_adam,
    ops::LargeScaleFuseAdamOpKernel<paddle::platform::CPUDeviceContext, float>);
