// Copyright (C) 2015  Davis E. King (davis@dlib.net)
// License: Boost Software License   See LICENSE.txt for the full license.
#ifndef DLIB_DNN_CuDNN_CPP_
#define DLIB_DNN_CuDNN_CPP_

#ifdef DLIB_USE_CUDA

#include "cudnn_dlibapi.h"
#include "tensor.h"
#include <cudnn.h>
#include <iostream>
#include <string>
#include "cuda_utils.h"


namespace dlib
{

    namespace cuda 
    {

        // TODO, make into a macro that prints more information like the line number, etc.
        static void check(cudnnStatus_t s)
        {
            switch(s)
            {
                case CUDNN_STATUS_SUCCESS: return;
                case CUDNN_STATUS_NOT_INITIALIZED: 
                    throw cudnn_error("CUDA Runtime API initialization failed.");
                case CUDNN_STATUS_ALLOC_FAILED: 
                    throw cudnn_error("CUDA Resources could not be allocated.");
                case CUDNN_STATUS_BAD_PARAM:
                    throw cudnn_error("CUDNN_STATUS_BAD_PARAM");
                default:
                    throw cudnn_error("A call to cuDNN failed: " + std::string(cudnnGetErrorString(s)));
            }
        }

    // ------------------------------------------------------------------------------------

        class cudnn_context
        {
        public:
            // not copyable 
            cudnn_context(const cudnn_context&) = delete;
            cudnn_context& operator=(const cudnn_context&) = delete;

            cudnn_context()
            {
                check(cudnnCreate(&handle));
            }

            ~cudnn_context()
            {
                cudnnDestroy(handle);
            }

            cudnnHandle_t get_handle (
            ) const { return handle; }

        private:
            cudnnHandle_t handle;
        };

        static cudnnHandle_t context()
        {
            thread_local cudnn_context c;
            return c.get_handle();
        }

    // ------------------------------------------------------------------------------------

        tensor_descriptor::
        tensor_descriptor(
        ) : handle(nullptr)
        {
        }

        tensor_descriptor::
        ~tensor_descriptor()
        {
            set_size(0,0,0,0);
        }

        void tensor_descriptor::
        set_size(
            int n, 
            int nr, 
            int nc, 
            int k
        )
        {
            if (n == 0 || nr == 0 || nc == 0 || k == 0)
            {
                if (handle)
                {
                    cudnnDestroyTensorDescriptor((cudnnTensorDescriptor_t)handle);
                    handle = nullptr;
                }
            }
            else
            {
                cudnnTensorDescriptor_t h;
                check(cudnnCreateTensorDescriptor(&h));
                handle = h;

                check(cudnnSetTensor4dDescriptor((cudnnTensorDescriptor_t)handle,
                        CUDNN_TENSOR_NHWC,
                        CUDNN_DATA_FLOAT,
                        n,
                        k,
                        nr,
                        nc));
            }
        }

        void tensor_descriptor::
        get_size (
            int& n, 
            int& nr, 
            int& nc, 
            int& k
        ) const
        {
            if (handle)
            {
                int nStride, cStride, hStride, wStride;
                cudnnDataType_t datatype;
                check(cudnnGetTensor4dDescriptor((cudnnTensorDescriptor_t)handle,
                        &datatype,
                        &n,
                        &k,
                        &nr,
                        &nc,
                        &nStride,
                        &cStride,
                        &hStride,
                        &wStride));
            }
            else
            {
                n = 0;
                nr = 0;
                nc = 0;
                k = 0;
            }
        }

    // ------------------------------------------------------------------------------------

        void add(
            float beta,
            tensor& dest,
            float alpha,
            const tensor& src
        )
        {
        }

        void set_tensor (
            tensor& t,
            float value
        )
        {
        }

        void scale_tensor (
            tensor& t,
            float value
        )
        {
        }

    // ------------------------------------------------------------------------------------
    // ------------------------------------------------------------------------------------

        conv::
        conv(
        ) : 
            filter_handle(nullptr),
            conv_handle(nullptr),
            out_num_samples(0),
            out_k(0),
            out_nr(0),
            out_nc(0),
            forward_algo(0),
            forward_workspace_size_in_bytes(0),
            forward_workspace(nullptr)
        {
        }

        void conv::
        clear (
        )
        {
            if (filter_handle) 
                cudnnDestroyFilterDescriptor((cudnnFilterDescriptor_t)filter_handle);
            if (conv_handle) 
                cudnnDestroyConvolutionDescriptor((cudnnConvolutionDescriptor_t)conv_handle);
            filter_handle = nullptr;
            conv_handle = nullptr;
            out_num_samples = 0;
            out_k = 0;
            out_nr = 0;
            out_nc = 0;

            if (forward_workspace)
                cudaFree(forward_workspace);
            forward_workspace = nullptr;

            forward_algo = 0;
            forward_workspace_size_in_bytes = 0;
        }

        void conv::
        setup(
            const tensor& data,
            const tensor& filters,
            int stride_y_,
            int stride_x_
        ) 
        {
            DLIB_CASSERT(data.k() == filters.k(),"");
            clear();
            try
            {
                stride_y = stride_y_;
                stride_x = stride_x_;

                check(cudnnCreateFilterDescriptor((cudnnFilterDescriptor_t*)&filter_handle));
                check(cudnnSetFilter4dDescriptor((cudnnFilterDescriptor_t)filter_handle, 
                                                 CUDNN_DATA_FLOAT, 
                                                 filters.num_samples(),
                                                 filters.k(),
                                                 filters.nr(),
                                                 filters.nc()));

                check(cudnnCreateConvolutionDescriptor((cudnnConvolutionDescriptor_t*)&conv_handle));
                check(cudnnSetConvolution2dDescriptor((cudnnConvolutionDescriptor_t)conv_handle,
                        filters.nr()/2, // vertical padding
                        filters.nc()/2, // horizontal padding
                        stride_y,
                        stride_x,
                        1, 1, // must be 1,1
                        CUDNN_CONVOLUTION)); // could also be CUDNN_CROSS_CORRELATION

                check(cudnnGetConvolution2dForwardOutputDim(
                        (const cudnnConvolutionDescriptor_t)conv_handle,
                        (const cudnnTensorDescriptor_t)data.get_cudnn_tensor_descriptor().get_handle(),
                        (const cudnnFilterDescriptor_t)filter_handle,
                        &out_num_samples,
                        &out_k,
                        &out_nr,
                        &out_nc));

                tensor_descriptor dest_desc;
                dest_desc.set_size(out_num_samples,out_nr,out_nc,out_k);

                cudnnConvolutionFwdAlgo_t forward_best_algo;
                check(cudnnGetConvolutionForwardAlgorithm(
                        context(), 
                        (const cudnnTensorDescriptor_t)data.get_cudnn_tensor_descriptor().get_handle(),
                        (const cudnnFilterDescriptor_t)filter_handle,
                        (const cudnnConvolutionDescriptor_t)conv_handle,
                        (const cudnnTensorDescriptor_t)dest_desc.get_handle(),
                        CUDNN_CONVOLUTION_FWD_PREFER_FASTEST, // or CUDNN_CONVOLUTION_FWD_NO_WORKSPACE,
                        std::numeric_limits<size_t>::max(),
                        &forward_best_algo));
                forward_algo = forward_best_algo;


                check(cudnnGetConvolutionForwardWorkspaceSize( 
                        context(),
                        (const cudnnTensorDescriptor_t)data.get_cudnn_tensor_descriptor().get_handle(),
                        (const cudnnFilterDescriptor_t)filter_handle,
                        (const cudnnConvolutionDescriptor_t)conv_handle,
                        (const cudnnTensorDescriptor_t)dest_desc.get_handle(),
                        forward_best_algo,
                        &forward_workspace_size_in_bytes));

                CHECK_CUDA(cudaMalloc(&forward_workspace, forward_workspace_size_in_bytes));
            }
            catch(...)
            {
                clear();
            }
        }

        conv::
        ~conv (
        )
        {
            clear();
        }

        void conv::operator() (
            resizable_tensor& output,
            const tensor& data,
            const tensor& filters
        )
        {
            output.set_size(out_num_samples, out_nr, out_nc, out_k);


            // TODO, remove
            DLIB_CASSERT(output.num_samples() == data.num_samples(),out_num_samples << "  " << data.num_samples());
            DLIB_CASSERT(output.k() == filters.num_samples(),"");
            DLIB_CASSERT(output.nr() == 1+(data.nr()-1)/stride_y,"");
            DLIB_CASSERT(output.nc() == 1+(data.nc()-1)/stride_x,"");

            const float alpha = 1;
            const float beta = 0;
            check(cudnnConvolutionForward(
                    context(),
                    &alpha,
                    (const cudnnTensorDescriptor_t)data.get_cudnn_tensor_descriptor().get_handle(),
                    data.device(),
                    (const cudnnFilterDescriptor_t)filter_handle,
                    filters.device(),
                    (const cudnnConvolutionDescriptor_t)conv_handle,
                    (cudnnConvolutionFwdAlgo_t)forward_algo,
                    forward_workspace,
                    forward_workspace_size_in_bytes,
                    &beta,
                    (const cudnnTensorDescriptor_t)output.get_cudnn_tensor_descriptor().get_handle(),
                    output.device()));
        }

        void conv::get_gradient_for_data (
            const tensor& gradient_input, 
            const tensor& filters,
            tensor& data_gradient
        )
        {
        }

        void conv::
        get_gradient_for_filters (
            const tensor& gradient_input, 
            const tensor& data,
            tensor& filters_gradient
        )
        {
        }

    // ------------------------------------------------------------------------------------
    // ------------------------------------------------------------------------------------

        void soft_max (
            resizable_tensor& dest,
            const tensor& src
        )
        {
        }

        void soft_max_gradient (
            tensor& grad,
            const tensor& src,
            const tensor& gradient_input
        )
        {
        }

    // ------------------------------------------------------------------------------------
    // ------------------------------------------------------------------------------------

        max_pool::max_pool (
            int window_height,
            int window_width,
            int stride_y,
            int stride_x
        )
        {
        }

        max_pool::~max_pool(
        )
        {
        }

        void max_pool::
        operator() (
            resizable_tensor& dest,
            const tensor& src
        )
        {
        }

        void max_pool::get_gradient(
            const tensor& gradient_input, 
            const tensor& src,
            tensor& grad 
        )
        {
        }

    // ------------------------------------------------------------------------------------
    // ------------------------------------------------------------------------------------

        void sigmoid (
            resizable_tensor& dest,
            const tensor& src
        )
        {
        }

        void sigmoid_gradient (
            tensor& grad,
            const tensor& src,
            const tensor& gradient_input
        )
        {
        }

    // ------------------------------------------------------------------------------------

        void relu (
            resizable_tensor& dest,
            const tensor& src
        )
        {
        }

        void relu_gradient (
            tensor& grad,
            const tensor& src,
            const tensor& gradient_input
        )
        {
        }

    // ------------------------------------------------------------------------------------

        void tanh (
            resizable_tensor& dest,
            const tensor& src
        )
        {
        }

        void tanh_gradient (
            tensor& grad,
            const tensor& src,
            const tensor& gradient_input
        )
        {
        }

    // ------------------------------------------------------------------------------------

    } 
}

#endif // DLIB_USE_CUDA

#endif // DLIB_DNN_CuDNN_CPP_


