/* 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. */

#pragma once

#include "paddle/framework/enforce.h"
#include "paddle/platform/cuda.h"
#include "paddle/platform/dynload/cublas.h"
#include "paddle/platform/dynload/cudnn.h"
#include "paddle/platform/dynload/curand.h"
#define EIGEN_USE_GPU
#include "paddle/platform/place.h"
#include "unsupported/Eigen/CXX11/Tensor"

namespace paddle {
namespace platform {

class CUDADeviceContext;

template <>
Eigen::GpuDevice DeviceContext::get_eigen_device<Eigen::GpuDevice>() {
  return static_cast<CUDADeviceContext*>(this)->eigen_handle();
}

class GPUPlaceGuard {
 public:
  explicit GPUPlaceGuard(GPUPlace new_place) : previous_(GetCurrentDeviceId()) {
    if (previous_ != new_place) {
      paddle::platform::SetDeviceId(new_place.device);
    }
  }

  ~GPUPlaceGuard() { paddle::platform::SetDeviceId(previous_.device); }

 private:
  GPUPlace previous_;
};

class CUDADeviceContext : public DeviceContext {
 public:
  explicit Device(const GPUPlace gpu_place) : gpu_place_(gpu_place) {
    GPUPlaceGuard guard(gpu_place_);
    paddle::platform::throw_on_error(cudaStreamCreate(&stream_),
                                     "cudaStreamCreate failed");
    eigen_stream_ = new Eigen::CudaStreamDevice(&stream_);
    eigen_device_ = new Eigen::GpuDevice(eigen_stream_);
  }

  Place GetPlace() const override {
    Place retv = GPUPlace();
    return retv;
  }

  void Wait() {
    paddle::platform::throw_on_error(cudaStreamSynchronize(stream_),
                                     "cudaStreamSynchronize failed");
  }

  cudaStream_t stream() { return stream_; }

  Eigen::GpuDevice eigen_device() { return *eigen_device_; }

  cublasHandle_t cublas_handle() {
    if (!blas_handle_) {
      GPUPlaceGuard guard(gpu_place_);
      PADDLE_ENFORCE(paddle::platform::dynload::cublasCreate(&blas_handle_) ==
                         CUBLAS_STATUS_SUCCESS,
                     "cublasCreate failed");
      PADDLE_ENFORCE(paddle::platform::dynload::cublasSetStream(
                         blas_handle_, stream_) == CUBLAS_STATUS_SUCCESS,
                     "cublasSetStream failed");
    }
    return blas_handle_;
  }

  cudnnHandle_t cudnn_handle() {
    if (!dnn_handle_) {
      GPUPlaceGuard guard(gpu_place_);
      PADDLE_ENFORCE(paddle::platform::dynload::cudnnCreate(&dnn_handle_) ==
                         CUDNN_STATUS_SUCCESS,
                     "cudnnCreate failed");
      PADDLE_ENFORCE(paddle::platform::dynload::cudnnSetStream(
                         dnn_handle_, stream_) == CUDNN_STATUS_SUCCESS,
                     "cudnnSetStream failed");
    }
    return dnn_handle_;
  }

  curandGenerator_t curand_generator() {
    if (!rand_generator_) {
      GPUPlaceGuard guard(gpu_place_);
      PADDLE_ENFORCE(paddle::platform::dynload::curandCreateGenerator(
                         &rand_generator_, CURAND_RNG_PSEUDO_DEFAULT) ==
                         CURAND_STATUS_SUCCESS,
                     "curandCreateGenerator failed");
      PADDLE_ENFORCE(
          paddle::platform::dynload::curandSetPseudoRandomGeneratorSeed(
              rand_generator_, random_seed_) == CURAND_STATUS_SUCCESS,
          "curandSetPseudoRandomGeneratorSeed failed");
      PADDLE_ENFORCE(paddle::platform::dynload::curandSetStream(
                         rand_generator_, stream_) == CURAND_STATUS_SUCCESS,
                     "curandSetStream failed");
    }
    return rand_generator_;
  }

  ~CUDADeviceContext() {
    Wait();
    if (blas_handle_) {
      PADDLE_ENFORCE(paddle::platform::dynload::cublasDestroy(blas_handle_) ==
                         CUBLAS_STATUS_SUCCESS,
                     "cublasDestroy failed");
    }

    if (dnn_handle_) {
      PADDLE_ENFORCE(paddle::platform::dynload::cudnnDestroy(dnn_handle_) ==
                         CUDNN_STATUS_SUCCESS,
                     "cudnnDestroy failed");
    }

    if (rand_generator_) {
      PADDLE_ENFORCE(paddle::platform::dynload::curandDestroyGenerator(
                         rand_generator_) == CURAND_STATUS_SUCCESS,
                     "curandDestroyGenerator failed");
    }

    delete eigen_stream_;
    delete eigen_device_;

    paddle::platform::throw_on_error(cudaStreamDestroy(stream_),
                                     "cudaStreamDestroy failed");
  }

 private:
  GPUPlace gpu_place_;
  cudaStream_t stream_;

  Eigen::CudaStreamDevice* eigen_stream_;
  Eigen::GpuDevice* eigen_device_;

  cublasHandle_t blas_handle_{nullptr};

  cudnnHandle_t dnn_handle_{nullptr};

  int random_seed_;
  curandGenerator_t rand_generator_{nullptr};
};
}  // namespace platform
}  // namespace paddle