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#ifndef HIPCUB_ROCPRIM_DEVICE_DEVICE_SPMV_HPP_
#define HIPCUB_ROCPRIM_DEVICE_DEVICE_SPMV_HPP_

#include "../../../config.hpp"
#include "../../../util_deprecated.hpp"

#include "../iterator/tex_ref_input_iterator.hpp"
#include "../util_sync.hpp"

BEGIN_HIPCUB_NAMESPACE

class DeviceSpmv
{

public:

template <
    typename        ValueT,              ///< Matrix and vector value type
    typename        OffsetT>             ///< Signed integer type for sequence offsets
struct SpmvParams
{
    ValueT*         d_values;            ///< Pointer to the array of \p num_nonzeros values of the corresponding nonzero elements of matrix <b>A</b>.
    OffsetT*        d_row_end_offsets;   ///< Pointer to the array of \p m offsets demarcating the end of every row in \p d_column_indices and \p d_values
    OffsetT*        d_column_indices;    ///< Pointer to the array of \p num_nonzeros column-indices of the corresponding nonzero elements of matrix <b>A</b>.  (Indices are zero-valued.)
    ValueT*         d_vector_x;          ///< Pointer to the array of \p num_cols values corresponding to the dense input vector <em>x</em>
    ValueT*         d_vector_y;          ///< Pointer to the array of \p num_rows values corresponding to the dense output vector <em>y</em>
    int             num_rows;            ///< Number of rows of matrix <b>A</b>.
    int             num_cols;            ///< Number of columns of matrix <b>A</b>.
    int             num_nonzeros;        ///< Number of nonzero elements of matrix <b>A</b>.
    ValueT          alpha;               ///< Alpha multiplicand
    ValueT          beta;                ///< Beta addend-multiplicand

    ::hipcub::TexRefInputIterator<ValueT, 66778899, OffsetT>  t_vector_x;
};

static constexpr uint32_t CsrMVKernel_MaxThreads = 256;

template <typename ValueT>
static __global__ void
CsrMVKernel(SpmvParams<ValueT, int> spmv_params)
{
    __shared__ ValueT partial;

    const int32_t row_id = blockIdx.x;

    if(threadIdx.x == 0)
    {
        partial = spmv_params.beta * spmv_params.d_vector_y[row_id];
    }
    __syncthreads();

    int32_t row_offset = (row_id == 0) ? (0) : (spmv_params.d_row_end_offsets[row_id - 1]);
    for(uint32_t thread_offset = 0; thread_offset < spmv_params.num_cols / blockDim.x;
        thread_offset++)
    {
        int32_t offset = row_offset + thread_offset * blockDim.x + threadIdx.x;

        if(offset < spmv_params.d_row_end_offsets[row_id])
        {
            ValueT t_value =
                spmv_params.alpha *
                spmv_params.d_values[offset] *
                spmv_params.d_vector_x[spmv_params.d_column_indices[offset]];

            atomicAdd(&partial, t_value);

            __syncthreads();

            if(threadIdx.x == 0)
            {
                spmv_params.d_vector_y[row_id] = partial;
            }
        }
    }
}

template<typename ValueT>
HIPCUB_RUNTIME_FUNCTION static hipError_t CsrMV(void*       d_temp_storage,
                                                size_t&     temp_storage_bytes,
                                                ValueT*     d_values,
                                                int*        d_row_offsets,
                                                int*        d_column_indices,
                                                ValueT*     d_vector_x,
                                                ValueT*     d_vector_y,
                                                int         num_rows,
                                                int         num_cols,
                                                int         num_nonzeros,
                                                hipStream_t stream = 0)
{
    SpmvParams<ValueT, int> spmv_params;
    spmv_params.d_values          = d_values;
    spmv_params.d_row_end_offsets = d_row_offsets + 1;
    spmv_params.d_column_indices  = d_column_indices;
    spmv_params.d_vector_x        = d_vector_x;
    spmv_params.d_vector_y        = d_vector_y;
    spmv_params.num_rows          = num_rows;
    spmv_params.num_cols          = num_cols;
    spmv_params.num_nonzeros      = num_nonzeros;
    spmv_params.alpha             = 1.0;
    spmv_params.beta              = 0.0;

    if(d_temp_storage == nullptr)
    {
        // Make sure user won't try to allocate 0 bytes memory, because
        // hipMalloc will return nullptr when size is zero.
        temp_storage_bytes = 4;
        return hipError_t(0);
    } else
    {
        size_t block_size = min(num_cols, static_cast<int>(DeviceSpmv::CsrMVKernel_MaxThreads));
        size_t grid_size  = num_rows;

        std::chrono::high_resolution_clock::time_point start;
        if HIPCUB_IF_CONSTEXPR(HIPCUB_DETAIL_DEBUG_SYNC_VALUE)
        {
            start = std::chrono::high_resolution_clock::now();
        }
        CsrMVKernel<<<grid_size, block_size, 0, stream>>>(spmv_params);
        HIPCUB_DETAIL_HIP_SYNC_AND_RETURN_ON_ERROR("CsrMV", block_size * grid_size, start);
    }
    return hipSuccess;
}

template<typename ValueT>
HIPCUB_DETAIL_DEPRECATED_DEBUG_SYNCHRONOUS HIPCUB_RUNTIME_FUNCTION static hipError_t
    CsrMV(void*       d_temp_storage,
          size_t&     temp_storage_bytes,
          ValueT*     d_values,
          int*        d_row_offsets,
          int*        d_column_indices,
          ValueT*     d_vector_x,
          ValueT*     d_vector_y,
          int         num_rows,
          int         num_cols,
          int         num_nonzeros,
          hipStream_t stream,
          bool        debug_synchronous)
{
    HIPCUB_DETAIL_RUNTIME_LOG_DEBUG_SYNCHRONOUS();
    return CsrMV(d_temp_storage,
                 temp_storage_bytes,
                 d_values,
                 d_row_offsets,
                 d_column_indices,
                 d_vector_x,
                 d_vector_y,
                 num_rows,
                 num_cols,
                 num_nonzeros,
                 stream);
}
};

END_HIPCUB_NAMESPACE

#endif // HIPCUB_CUB_DEVICE_DEVICE_SELECT_HPP_

