// 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 "paddle/fluid/framework/op_registry.h"
#include "paddle/phi/core/kernel_registry.h"

namespace paddle {
namespace operators {

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

 protected:
  void InferShape(framework::InferShapeContext *ctx) const override {}

  phi::KernelKey GetExpectedKernelType(
      const framework::ExecutionContext &ctx) const override {
    auto dtype = framework::proto::VarType::FP32;  // dtype is not important
    return phi::KernelKey(dtype, ctx.GetPlace());
  }

  phi::KernelKey GetKernelTypeForVar(
      const std::string &var_name,
      const phi::DenseTensor &tensor,
      const phi::KernelKey &expected_kernel_type) const override {
    return phi::KernelKey(phi::Backend::ALL_BACKEND,
                          expected_kernel_type.layout(),
                          expected_kernel_type.dtype());
  }
};

class DistributedFusedLambOpMaker : public framework::OpProtoAndCheckerMaker {
 public:
  void Make() override {
    AddInput("Param", "The initial parameter list.").AsDuplicable();
    AddInput("Grad", "The initial gradient list.").AsDuplicable();

    AddInput("FP32FusedParam",
             "The fp32 fused param and fp16 fused master weight tensor. Its "
             "shape is [M1+M2], where M1 is the fp32 fused parameter size and "
             "M2 is the fp16 fused master weight parameter size. Note that M1 "
             "and M2 should be exactly divided by N (guaranteed by extra "
             "padding 0), where N is the world size.")
        .AsDispensable();
    AddInput("FP32FusedGrad", "The fp32 fused grad tensor. Its shape is [M1].")
        .AsDispensable();
    AddInput("FP16FusedParam",
             "The fp16 fused param tensor. Its shape is [M2].")
        .AsDispensable();
    AddInput("FP16FusedGrad", "The fp16 fused grad tensor. Its shape is [M2].")
        .AsDispensable();

    AddInput("Moment1",
             "The sharded fp32 moment1 tensor. Its shape is [(M1+M2)/N].");
    AddInput("Moment2",
             "The sharded fp32 moment2 tensor. Its shape is [(M1+M2)/N].");
    AddInput("Beta1Pow",
             "The fp32 beta1 power accumulator tensor. Its shape is [1].");
    AddInput("Beta2Pow",
             "The fp32 beta2 power accumulator tensor. Its shape is [1].");
    AddInput(
        "FusedParamOffsets",
        "The numel offset of each parameter inside the FP32FusedParam. Its "
        "shape is [param_num + 1]. It is like [0, n_0, n_0 + n_1, n_0 + n_1 "
        "+ n_2, ...]. It should be in CPUPlace.");
    AddInput(
        "FP32ShardFusedParamOffsets",
        "The sharded numel offset of each parameter in the local rank. "
        "Its shape is [fp32_local_param_num + 1]. It should be in CPUPlace.");
    AddInput(
        "FP16ShardFusedParamOffsets",
        "The sharded numel offset of each parameter in the local rank. "
        "Its shape is [fp16_local_param_num + 1]. It should be in CPUPlace.");
    AddInput("ParamInfo",
             "The param info. It should be in CPUPlace, and its shape is [6]"
             "CPUPlace, and its shape is [8]. It is "
             "[fp32_shard_param_start_idx, fp32_local_param_num, "
             "fp32_global_param_num, fp32_weight_decay_end_idx, "
             "fp16_shard_param_start_idx, "
             "fp16_local_param_num, fp16_global_param_num, "
             "fp16_weight_decay_end_idx].");
    AddInput("ParamOrder",
             "The reordered parameter order. Inside this op, "
             "the parameter would be reordered by data type and weight decay "
             "value.");

    AddInput("LearningRate",
             "The fp32 learning rate tensor. Its shape is [1].");
    AddInput("GlobalScale", "The fp32 global scale tensor. Its shape is [1].");

    AddOutput("FP32FusedParamOut", "The updated FP32FusedParam.")
        .AsDispensable();
    AddOutput("FP16FusedParamOut", "The updated FP16FusedParam.")
        .AsDispensable();
    AddOutput("FP32AccFusedGrad", "The accumulated FP32 gradients.")
        .AsDispensable();
    AddOutput("FP16AccFusedGrad", "The accumulated FP16 gradients.")
        .AsDispensable();

    AddOutput("Moment1Out", "The updated Moment1.");
    AddOutput("Moment2Out", "The updated Moment2.");
    AddOutput("Beta1PowOut", "The updated Beta1Pow.");
    AddOutput("Beta2PowOut", "The updated Beta2Pow.");

    AddOutput("ParamOut", "The updated output parameter tensor list.")
        .AsDuplicable();

    AddOutput("FoundInf", "Whether there is NaN/Inf");
    AddOutput("AccStep", "The training steps.").AsDispensable();
    AddOutput("StopUpdate",
              "Whether the parameter updating is stopped when the gradient "
              "accumulated steps is less than Attr(acc_steps).")
        .AsDispensable();
    AddOutput("Step", "The global step which excludes the NaN/Inf step.");

    AddAttr<int>("acc_steps", "The gradient accumulation steps.").SetDefault(1);
    AddAttr<float>("beta1", "The initial Beta1Pow value.");
    AddAttr<float>("beta2", "The initial Beta2Pow value.");
    AddAttr<float>("epsilon",
                   "The epsilon value to maintain numeric stability.");
    AddAttr<float>(
        "max_global_grad_norm",
        "The maximum global gradient l2-norm value for clipping. If "
        "max_global_grad_norm <= 0, no clipping would be performed.");
    AddAttr<float>("weight_decay", "The weight decay value.");
    AddAttr<bool>("clip_after_allreduce",
                  "Whether to clip before allreduce, only valid when the "
                  "world size is larger than 1.");
    AddAttr<bool>(
        "use_master_param_norm",
        "Whether to use master parameter to calculate "
        "the L2-Norm. If it is true, it would be more accurate but be more "
        "NCCL communication data. If it is false, it would be less accurate "
        "and be less NCCL communication data.")
        .SetDefault(true);
    AddAttr<bool>("use_master_acc_grad",
                  "Whether to use master gradient when acc_steps > 1.")
        .SetDefault(true);
    AddAttr<bool>("is_grad_scaled_by_nranks",
                  "Whether the input gradient has been scaled by nranks.")
        .SetDefault(true);
    AddAttr<int64_t>("nranks", "The world size.").SetDefault(1);
    AddAttr<std::vector<int>>("ring_ids",
                              "The ring ids of the NCCL communicator.")
        .SetDefault({0});
    AddAttr<bool>("use_hierarchical_allreduce",
                  "Whether to use hierarchical allreduce")
        .SetDefault(false);
    AddComment("The DistributedFusedLamb optimizer.");
  }
};

}  // namespace operators
}  // namespace paddle

namespace plat = paddle::platform;
namespace ops = paddle::operators;
REGISTER_OP_WITHOUT_GRADIENT(distributed_fused_lamb,
                             ops::DistributedFusedLambOp,
                             ops::DistributedFusedLambOpMaker);

namespace phi {
namespace fusion {

template <typename T, typename Context>
void DistributedFusedLambKernel(const Context &dev_ctx,
                                const std::vector<const DenseTensor *> &param,
                                const std::vector<const DenseTensor *> &grad,
                                const paddle::optional<DenseTensor> &fp32_param,
                                const paddle::optional<DenseTensor> &fp32_grad,
                                const paddle::optional<DenseTensor> &fp16_param,
                                const paddle::optional<DenseTensor> &fp16_grad,
                                const DenseTensor &moment1,
                                const DenseTensor &moment2,
                                const DenseTensor &beta1_pow,
                                const DenseTensor &beta2_pow,
                                const DenseTensor &param_offsets,
                                const DenseTensor &fp32_partial_offsets,
                                const DenseTensor &fp16_partial_offsets,
                                const DenseTensor &param_info,
                                const DenseTensor &param_order,
                                const DenseTensor &learning_rate,
                                const DenseTensor &global_scale,
                                int acc_steps,
                                float beta1,
                                float beta2,
                                float epsilon,
                                float max_global_grad_norm,
                                float weight_decay,
                                bool clip_after_allreduce,
                                bool use_master_param_norm,
                                bool use_master_acc_grad,
                                bool is_grad_scaled_by_nranks,
                                bool use_hierarchical_allreduce,
                                int64_t nranks,
                                const std::vector<int> &ring_ids,
                                DenseTensor *fp32_param_out,
                                DenseTensor *fp16_param_out,
                                DenseTensor *fp32_acc_grad,
                                DenseTensor *fp16_acc_grad,
                                DenseTensor *moment1_out,
                                DenseTensor *moment2_out,
                                DenseTensor *beta1_pow_out,
                                DenseTensor *beta2_pow_out,
                                DenseTensor *param_out,
                                DenseTensor *found_inf,
                                DenseTensor *acc_step,
                                DenseTensor *stop_update,
                                DenseTensor *step) {
  PADDLE_THROW(phi::errors::Unimplemented(
      "The distributed_fused_lamb operator does not support CPU yet."));
}

}  // namespace fusion
}  // namespace phi

PD_REGISTER_KERNEL(distributed_fused_lamb,
                   CPU,
                   ALL_LAYOUT,
                   phi::fusion::DistributedFusedLambKernel,
                   float) {}
