// Copyright (c) 2022 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.

#pragma once

#include "paddle/phi/common/amp_type_traits.h"
#include "paddle/phi/core/dense_tensor.h"
#include "paddle/phi/core/hostdevice.h"
#include "paddle/phi/core/macros.h"
#include "paddle/phi/kernels/funcs/for_range.h"
#include "paddle/phi/kernels/impl/momentum_kernel_impl.h"
#include "paddle/phi/kernels/merged_momentum_kernel.h"

namespace phi {

template <typename T>
using MultiPrecisionType = typename phi::dtype::MPTypeTrait<T>::Type;

template <typename MT, uint32_t kParamNum, bool kHasMasterParams>
struct MergedMomentumMasterParams {
  MT *PADDLE_RESTRICT master_params[kParamNum];

  HOSTDEVICE MT *MasterParam(size_t idx) const { return master_params[idx]; }
  HOSTDEVICE void SetMasterParam(size_t idx, MT *p) { master_params[idx] = p; }
};

template <typename MT, uint32_t kParamNum>
struct MergedMomentumMasterParams<MT, kParamNum, false> {
  HOSTDEVICE constexpr MT *MasterParam(size_t) const { return nullptr; }
  HOSTDEVICE constexpr void SetMasterParam(size_t, MT *) {}
};

template <typename T,
          typename MT,
          bool kHasMasterParams,
          uint32_t kParamNum = kHasMasterParams ? 55 : 110>
struct MergedMomentumKernelParam
    : public MergedMomentumMasterParams<MT, kParamNum, kHasMasterParams> {
  static constexpr auto N = kParamNum;
  size_t sizes[N];
  T *PADDLE_RESTRICT params[N];
  const T *PADDLE_RESTRICT grads[N];
  MT *PADDLE_RESTRICT velocitys[N];
  const MultiPrecisionType<MT> *PADDLE_RESTRICT lr;
  MT mu;
  MT rescale_grad;
  uint32_t param_num;

  HOSTDEVICE void operator()(size_t i) const {
    const MT lr_val = static_cast<MT>(*lr);
    for (uint32_t idx = 0; idx < param_num; ++idx) {
      auto size = sizes[idx];
      if (i >= size) continue;

      auto param_p = params[idx];
      auto grad_p = grads[idx];
      auto velocity_p = velocitys[idx];
      auto master_param_p = this->MasterParam(idx);

      const MT param =
          master_param_p ? master_param_p[i] : static_cast<MT>(param_p[i]);
      const MT grad = static_cast<MT>(grad_p[i]) * rescale_grad;
      const MT velocity = velocity_p[i];
      const MT velocity_out = velocity * mu + grad;
      const MT param_out = param - lr_val * velocity_out;
      velocity_p[i] = velocity_out;
      param_p[i] = static_cast<T>(param_out);
      if (master_param_p) {
        master_param_p[i] = param_out;
      }
    }
  }
};

template <typename MT, typename Context, typename MPType, typename T>
void MergedMomentumInnerCompute(
    const Context &ctx,
    const std::vector<const DenseTensor *> &params,
    const std::vector<const DenseTensor *> &grads,
    const std::vector<const DenseTensor *> &velocitys,
    const std::vector<const DenseTensor *> &lrs,
    const paddle::optional<std::vector<const DenseTensor *>> &master_params_opt,
    float mu,
    bool use_nesterov,
    const std::vector<std::string> &regularization_methods,
    const std::vector<float> &regularization_coeffs,
    float rescale_grad,
    const bool multi_precision,
    std::vector<DenseTensor *> params_out,
    std::vector<DenseTensor *> velocitys_out,
    std::vector<DenseTensor *> master_params_out) {
  size_t n = params.size();
  PADDLE_ENFORCE_EQ(n,
                    params_out.size(),
                    phi::errors::InvalidArgument(
                        "The size of Output(ParamOut) must be equal to "
                        "Input(Param), but got the size of Output(ParamOut) "
                        "is %d, the size of Input(Param) is %d.",
                        params_out.size(),
                        n));
  for (size_t i = 0; i < n; ++i) {
    PADDLE_ENFORCE_EQ(
        params[i],
        params_out[i],
        phi::errors::InvalidArgument("Input(Param) and Output(ParamOut) "
                                     "must be the same Tensors."));
  }

  PADDLE_ENFORCE_EQ(
      n,
      grads.size(),
      phi::errors::InvalidArgument(
          "The size of Input(Grad) must be equal to Input(Param), but got "
          "the size of Input(Grad) is %d, the size of Input(Param) is %d.",
          grads.size(),
          n));

  PADDLE_ENFORCE_EQ(n,
                    velocitys.size(),
                    phi::errors::InvalidArgument(
                        "The size of Input(Velocity) must be equal to "
                        "Input(Param), but got the size of Input(Velocity) "
                        "is %d, the size of Input(Param) is %d.",
                        velocitys.size(),
                        n));

  PADDLE_ENFORCE_EQ(
      n,
      velocitys_out.size(),
      phi::errors::InvalidArgument(
          "The size of Output(VelocityOut) must be "
          "equal to Input(Param), but got the size of Output(VelocityOut) is "
          "%d, the size of Input(Param) is %d.",
          velocitys_out.size(),
          n));
  for (size_t i = 0; i < n; ++i) {
    PADDLE_ENFORCE_EQ(velocitys[i],
                      velocitys_out[i],
                      phi::errors::InvalidArgument(
                          "Input(Velocity) and Output(VelocityOut) must be "
                          "the same Tensors."));
  }

  if (multi_precision) {
    auto master_params = master_params_opt.get();
    PADDLE_ENFORCE_EQ(
        n,
        master_params.size(),
        phi::errors::InvalidArgument(
            "The size of Input(MasterParam) must be "
            "equal to Input(Param), but got the size of Input(MasterParam) "
            "is %d, the size of Input(Param) is %d.",
            master_params.size(),
            n));
    PADDLE_ENFORCE_EQ(
        n,
        master_params_out.size(),
        phi::errors::InvalidArgument(
            "The size of Output(MasterParamOut) must be equal to "
            "Input(MasterParam), but got the size of Output(MasterParamOut) "
            "is %d, the size of Input(Param) is %d.",
            master_params_out.size(),
            n));
    for (size_t i = 0; i < n; ++i) {
      PADDLE_ENFORCE_EQ(master_params[i],
                        master_params_out[i],
                        phi::errors::InvalidArgument(
                            "Input(MasterParam) and Output(MasterParamOut) "
                            "must be the same Tensors."));
      PADDLE_ENFORCE_NOT_NULL(master_params[i],
                              phi::errors::InvalidArgument(
                                  "Input(MasterParam) must be provided when "
                                  "multi_precision=True."));
    }
  } else {
    master_params_out.clear();
  }

  if (lrs.size() != 1) {
    PADDLE_ENFORCE_EQ(
        n,
        lrs.size(),
        phi::errors::InvalidArgument(
            "If the size of Input(LearningRate) is not 1, the size of "
            "Input(LearningRate) must be "
            "equal to Input(Param), but got the size of Input(LearningRate) "
            "is %d, the size of Input(Param) is %d.",
            lrs.size(),
            n));
  }
  if (regularization_methods.size() != 0) {
    PADDLE_ENFORCE_EQ(
        n,
        regularization_methods.size(),
        phi::errors::InvalidArgument(
            "The size of Attr(regularization_method) must be equal "
            "to Input(Param), but got the size of "
            "Attr(regularization_method) is %d, the size of Input(Param) is "
            "%d.",
            regularization_methods.size(),
            n));
    PADDLE_ENFORCE_EQ(
        n,
        regularization_coeffs.size(),
        phi::errors::InvalidArgument(
            "The size of Attr(regularization_coeff) must be equal "
            "to Input(Param), but got the size of Attr(regularization_coeff) "
            "is %d, the size of Input(Param) is %d.",
            regularization_coeffs.size(),
            n));
  }

  VLOG(5) << "use_nesterov: " << use_nesterov
          << ",  regularization_methods.size(): "
          << regularization_methods.size()
          << ",  regularization_coeffs.size(): "
          << regularization_coeffs.size();

  if (lrs.size() == 1 && use_nesterov == false &&
      regularization_methods.size() == 0) {
#define PADDLE_LAUNCH_MERGED_MOMENTUM_KERNEL(kMultiPrecision)            \
  MergedMomentumKernelParam<T, MT, kMultiPrecision> kernel_params;       \
  constexpr auto kMaxMergedNum = decltype(kernel_params)::N;             \
  size_t kernel_num = (n + kMaxMergedNum - 1) / kMaxMergedNum;           \
  kernel_params.mu = static_cast<MT>(mu);                                \
  kernel_params.rescale_grad = static_cast<MT>(rescale_grad);            \
  kernel_params.lr = lrs[0]->data<MPType>();                             \
  for (size_t i = 0; i < kernel_num; ++i) {                              \
    size_t start = i * kMaxMergedNum;                                    \
    size_t end = std::min((i + 1) * kMaxMergedNum, n);                   \
    kernel_params.param_num = static_cast<uint32_t>(end - start);        \
    size_t max_size = 0;                                                 \
    for (size_t j = 0; j < kernel_params.param_num; ++j) {               \
      auto size = static_cast<size_t>(params_out[j + start]->numel());   \
      max_size = std::max(max_size, size);                               \
      kernel_params.sizes[j] = size;                                     \
      kernel_params.params[j] = params_out[j + start]->data<T>();        \
      kernel_params.grads[j] = grads[j + start]->data<T>();              \
      kernel_params.velocitys[j] = velocitys_out[j + start]->data<MT>(); \
      kernel_params.SetMasterParam(                                      \
          j,                                                             \
          kMultiPrecision ? master_params_out[j + start]->data<MT>()     \
                          : nullptr);                                    \
    }                                                                    \
    phi::funcs::ForRange<Context> for_range(ctx, max_size);              \
    for_range(kernel_params);                                            \
    VLOG(10) << "Launch MergedMomentum kernel " << i << " "              \
             << kernel_params.param_num;                                 \
  }
    if (multi_precision) {
      PADDLE_LAUNCH_MERGED_MOMENTUM_KERNEL(true);
    } else {
      PADDLE_LAUNCH_MERGED_MOMENTUM_KERNEL(false);
    }
#undef PADDLE_LAUNCH_MERGED_MOMENTUM_KERNEL
  } else {
    for (size_t idx = 0; idx < n; idx++) {
      phi::RegularizationType regularization_flag =
          regularization_methods.size() > 0 &&
                  regularization_methods[idx] == "l2_decay"
              ? phi::RegularizationType::kL2DECAY
              : phi::RegularizationType::kNONE;

      MT regularization_coeff = static_cast<MT>(0.0);
      if (regularization_coeffs.size() != 0) {
        regularization_coeff = static_cast<MT>(regularization_coeffs[idx]);
      }
      auto lr_temp = lrs.size() > 1 ? lrs[idx] : lrs[0];

      const MT *master_in_data =
          multi_precision ? master_params_opt.get()[idx]->data<MT>() : nullptr;
      MT *master_out_data =
          multi_precision ? master_params_out[idx]->data<MT>() : nullptr;
      if (paddle::platform::is_cpu_place(ctx.GetPlace())) {
        phi::CPUDenseMomentumFunctor<MT> functor;
        functor(params[idx],
                grads[idx],
                velocitys[idx],
                lr_temp,
                static_cast<MT>(mu),
                use_nesterov,
                regularization_flag,
                regularization_coeff,
                params_out[idx],
                velocitys_out[idx]);
        VLOG(10) << "Launch MergedMomentum cpu kernel.";
      } else if (paddle::platform::is_gpu_place(ctx.GetPlace())) {
        phi::funcs::ForRange<Context> for_range(
            static_cast<const Context &>(ctx), params[idx]->numel());
#define PADDLE_LAUNCH_DENSE_MTMOMENTUM_KERNEL(__nesterov, __reg_type) \
  phi::DenseMomentumFunctor<T, MT, __reg_type, __nesterov> functor(   \
      params[idx]->data<T>(),                                         \
      grads[idx]->data<T>(),                                          \
      velocitys[idx]->data<MT>(),                                     \
      lr_temp->data<MPType>(),                                        \
      master_in_data,                                                 \
      static_cast<MT>(mu),                                            \
      static_cast<MT>(rescale_grad),                                  \
      params[idx]->numel(),                                           \
      regularization_coeff,                                           \
      params_out[idx]->data<T>(),                                     \
      velocitys_out[idx]->data<MT>(),                                 \
      master_out_data);                                               \
  for_range(functor);
        if (use_nesterov) {
          if (regularization_flag == phi::RegularizationType::kL2DECAY) {
            PADDLE_LAUNCH_DENSE_MTMOMENTUM_KERNEL(
                phi::UseNesterov, phi::RegularizationType::kL2DECAY);
            VLOG(10)
                << "Launch MergedMomentum gpu kernel use_nesterov kL2DECAY.";
          } else {
            PADDLE_LAUNCH_DENSE_MTMOMENTUM_KERNEL(
                phi::UseNesterov, phi::RegularizationType::kNONE);
            VLOG(10) << "Launch MergedMomentum gpu kernel use_nesterov kNONE.";
          }
        } else {
          if (regularization_flag == phi::RegularizationType::kL2DECAY) {
            PADDLE_LAUNCH_DENSE_MTMOMENTUM_KERNEL(
                phi::NoNesterov, phi::RegularizationType::kL2DECAY);
            VLOG(10)
                << "Launch MergedMomentum gpu kernel no_nesterov kL2DECAY.";
          } else {
            PADDLE_LAUNCH_DENSE_MTMOMENTUM_KERNEL(
                phi::NoNesterov, phi::RegularizationType::kNONE);
            VLOG(10) << "Launch MergedMomentum gpu kernel no_nesterov kNONE.";
          }
        }
      }
    }
    VLOG(10)
        << "Launch MergedMomentum kernel with multi_lr and regularization.";
  }
}

template <typename T, typename Context>
void MergedMomentumKernel(
    const Context &dev_ctx,
    const std::vector<const DenseTensor *> &param,
    const std::vector<const DenseTensor *> &grad,
    const std::vector<const DenseTensor *> &velocity,
    const std::vector<const DenseTensor *> &learning_rate,
    const paddle::optional<std::vector<const DenseTensor *>> &master_param,
    float mu,
    bool use_nesterov,
    const std::vector<std::string> &regularization_method,
    const std::vector<float> &regularization_coeff,
    bool multi_precision,
    float rescale_grad,
    std::vector<DenseTensor *> param_out,
    std::vector<DenseTensor *> velocity_out,
    std::vector<DenseTensor *> master_param_out) {
  using MPType = typename phi::dtype::MPTypeTrait<T>::Type;
  if (multi_precision) {
    MergedMomentumInnerCompute<MPType, Context, MPType, T>(
        dev_ctx,
        param,
        grad,
        velocity,
        learning_rate,
        master_param,
        mu,
        use_nesterov,
        regularization_method,
        regularization_coeff,
        rescale_grad,
        multi_precision,
        param_out,
        velocity_out,
        master_param_out);
  } else {
    MergedMomentumInnerCompute<T, Context, MPType, T>(dev_ctx,
                                                      param,
                                                      grad,
                                                      velocity,
                                                      learning_rate,
                                                      master_param,
                                                      mu,
                                                      use_nesterov,
                                                      regularization_method,
                                                      regularization_coeff,
                                                      rescale_grad,
                                                      multi_precision,
                                                      param_out,
                                                      velocity_out,
                                                      master_param_out);
  }
}

}  // namespace phi
