/******************************************************************************
 * Copyright (c) 2011, Duane Merrill.  All rights reserved.
 * Copyright (c) 2011-2018, NVIDIA CORPORATION.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the NVIDIA CORPORATION nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 ******************************************************************************/

/**
 * @file
 *   cub::DeviceSelect provides device-wide, parallel operations for selecting items from sequences
 *   of data items residing within device-accessible memory.
 */

#pragma once

#include <cub/config.cuh>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cub/agent/agent_select_if.cuh>
#include <cub/device/dispatch/dispatch_scan.cuh>
#include <cub/device/dispatch/tuning/tuning_select_if.cuh>
#include <cub/grid/grid_queue.cuh>
#include <cub/thread/thread_operators.cuh>
#include <cub/util_deprecated.cuh>
#include <cub/util_device.cuh>
#include <cub/util_math.cuh>

#include <thrust/system/cuda/detail/core/triple_chevron_launch.h>

#include <cstdio>
#include <iterator>

#include <nv/target>

CUB_NAMESPACE_BEGIN

namespace detail
{
/**
 * @brief Wrapper that partially specializes the `AgentSelectIf` on the non-type name parameter `KeepRejects`.
 */
template <bool KeepRejects>
struct agent_select_if_wrapper_t
{
  // Using an explicit list of template parameters forwarded to AgentSelectIf, since MSVC complains about a template
  // argument following a parameter pack expansion like `AgentSelectIf<Ts..., KeepRejects>`
  template <typename AgentSelectIfPolicyT,
            typename InputIteratorT,
            typename FlagsInputIteratorT,
            typename SelectedOutputIteratorT,
            typename SelectOpT,
            typename EqualityOpT,
            typename OffsetT>
  struct agent_t
      : public AgentSelectIf< AgentSelectIfPolicyT,
                              InputIteratorT,
                              FlagsInputIteratorT,
                              SelectedOutputIteratorT,
                              SelectOpT,
                              EqualityOpT,
                              OffsetT,
                              KeepRejects>
  {
    using AgentSelectIf< AgentSelectIfPolicyT,
                         InputIteratorT,
                         FlagsInputIteratorT,
                         SelectedOutputIteratorT,
                         SelectOpT,
                         EqualityOpT,
                         OffsetT,
                         KeepRejects>::AgentSelectIf;
  };
};
} // namespace detail

/******************************************************************************
 * Kernel entry points
 *****************************************************************************/

/**
 * Select kernel entry point (multi-block)
 *
 * Performs functor-based selection if SelectOpT functor type != NullType
 * Otherwise performs flag-based selection if FlagsInputIterator's value type != NullType
 * Otherwise performs discontinuity selection (keep unique)
 *
 * @tparam InputIteratorT
 *   Random-access input iterator type for reading input items
 *
 * @tparam FlagsInputIteratorT
 *   Random-access input iterator type for reading selection flags (NullType* if a selection functor
 *   or discontinuity flagging is to be used for selection)
 *
 * @tparam SelectedOutputIteratorT
 *   Random-access output iterator type for writing selected items
 *
 * @tparam NumSelectedIteratorT
 *   Output iterator type for recording the number of items selected
 *
 * @tparam ScanTileStateT
 *   Tile status interface type
 *
 * @tparam SelectOpT
 *   Selection operator type (NullType if selection flags or discontinuity flagging is
 *   to be used for selection)
 *
 * @tparam EqualityOpT
 *   Equality operator type (NullType if selection functor or selection flags is
 *   to be used for selection)
 *
 * @tparam OffsetT
 *   Signed integer type for global offsets
 *
 * @tparam KEEP_REJECTS
 *   Whether or not we push rejected items to the back of the output
 *
 * @param[in] d_in
 *   Pointer to the input sequence of data items
 *
 * @param[in] d_flags
 *   Pointer to the input sequence of selection flags (if applicable)
 *
 * @param[out] d_selected_out
 *   Pointer to the output sequence of selected data items
 *
 * @param[out] d_num_selected_out
 *   Pointer to the total number of items selected (i.e., length of \p d_selected_out)
 *
 * @param[in] tile_status
 *   Tile status interface
 *
 * @param[in] select_op
 *   Selection operator
 *
 * @param[in] equality_op
 *   Equality operator
 *
 * @param[in] num_items
 *   Total number of input items (i.e., length of \p d_in)
 *
 * @param[in] num_tiles
 *   Total number of tiles for the entire problem
 *
 * @param[in] vsmem
 *   Memory to support virtual shared memory
 */
template <typename ChainedPolicyT,
          typename InputIteratorT,
          typename FlagsInputIteratorT,
          typename SelectedOutputIteratorT,
          typename NumSelectedIteratorT,
          typename ScanTileStateT,
          typename SelectOpT,
          typename EqualityOpT,
          typename OffsetT,
          bool KEEP_REJECTS>
__launch_bounds__(int(
  cub::detail::vsmem_helper_default_fallback_policy_t<
    typename ChainedPolicyT::ActivePolicy::SelectIfPolicyT,
    detail::agent_select_if_wrapper_t<KEEP_REJECTS>::template agent_t,
    InputIteratorT,
    FlagsInputIteratorT,
    SelectedOutputIteratorT,
    SelectOpT,
    EqualityOpT,
    OffsetT>::agent_policy_t::BLOCK_THREADS))
  CUB_DETAIL_KERNEL_ATTRIBUTES void DeviceSelectSweepKernel(
    InputIteratorT d_in,
    FlagsInputIteratorT d_flags,
    SelectedOutputIteratorT d_selected_out,
    NumSelectedIteratorT d_num_selected_out,
    ScanTileStateT tile_status,
    SelectOpT select_op,
    EqualityOpT equality_op,
    OffsetT num_items,
    int num_tiles,
    cub::detail::vsmem_t vsmem)
{
  using VsmemHelperT = cub::detail::vsmem_helper_default_fallback_policy_t<
    typename ChainedPolicyT::ActivePolicy::SelectIfPolicyT,
    detail::agent_select_if_wrapper_t<KEEP_REJECTS>::template agent_t,
    InputIteratorT,
    FlagsInputIteratorT,
    SelectedOutputIteratorT,
    SelectOpT,
    EqualityOpT,
    OffsetT>;

  using AgentSelectIfPolicyT = typename VsmemHelperT::agent_policy_t;

  // Thread block type for selecting data from input tiles
  using AgentSelectIfT = typename VsmemHelperT::agent_t;

  // Static shared memory allocation
  __shared__ typename VsmemHelperT::static_temp_storage_t static_temp_storage;

  // Get temporary storage
  typename AgentSelectIfT::TempStorage& temp_storage = VsmemHelperT::get_temp_storage(static_temp_storage, vsmem);

  // Process tiles
  AgentSelectIfT(temp_storage, d_in, d_flags, d_selected_out, select_op, equality_op, num_items)
    .ConsumeRange(num_tiles, tile_status, d_num_selected_out);

  // If applicable, hints to discard modified cache lines for vsmem
  VsmemHelperT::discard_temp_storage(temp_storage);
}


/******************************************************************************
 * Dispatch
 ******************************************************************************/

/**
 * Utility class for dispatching the appropriately-tuned kernels for DeviceSelect
 *
 * @tparam InputIteratorT
 *   Random-access input iterator type for reading input items
 *
 * @tparam FlagsInputIteratorT
 *   Random-access input iterator type for reading selection flags
 *   (NullType* if a selection functor or discontinuity flagging is to be used for selection)
 *
 * @tparam SelectedOutputIteratorT
 *   Random-access output iterator type for writing selected items
 *
 * @tparam NumSelectedIteratorT
 *   Output iterator type for recording the number of items selected
 *
 * @tparam SelectOpT
 *   Selection operator type (NullType if selection flags or discontinuity flagging is
 *   to be used for selection)
 *
 * @tparam EqualityOpT
 *   Equality operator type (NullType if selection functor or selection flags is to
 *   be used for selection)
 *
 * @tparam OffsetT
 *   Signed integer type for global offsets
 *
 * @tparam KEEP_REJECTS
 *   Whether or not we push rejected items to the back of the output
 */
template <typename InputIteratorT,
          typename FlagsInputIteratorT,
          typename SelectedOutputIteratorT,
          typename NumSelectedIteratorT,
          typename SelectOpT,
          typename EqualityOpT,
          typename OffsetT,
          bool KEEP_REJECTS,
          bool MayAlias = false,
          typename SelectedPolicy =
            detail::device_select_policy_hub<cub::detail::value_t<InputIteratorT>,
                                             cub::detail::value_t<FlagsInputIteratorT>,
                                             OffsetT,
                                             MayAlias,
                                             KEEP_REJECTS>>
struct DispatchSelectIf : SelectedPolicy
{
    /******************************************************************************
     * Types and constants
     ******************************************************************************/

    // Tile status descriptor interface type
    using ScanTileStateT = ScanTileState<OffsetT>;

    static constexpr int INIT_KERNEL_THREADS = 128;

    /// Device-accessible allocation of temporary storage.
    /// When `nullptr`, the required allocation size is written to `temp_storage_bytes`
    /// and no work is done.
    void* d_temp_storage;

    /// Reference to size in bytes of `d_temp_storage` allocation
    size_t& temp_storage_bytes;

    /// Pointer to the input sequence of data items
    InputIteratorT d_in;

    /// Pointer to the input sequence of selection flags (if applicable)
    FlagsInputIteratorT d_flags;

    /// Pointer to the output sequence of selected data items
    SelectedOutputIteratorT d_selected_out;

    /// Pointer to the total number of items selected (i.e., length of `d_selected_out`)
    NumSelectedIteratorT d_num_selected_out;

    /// Selection operator
    SelectOpT select_op;

    /// Equality operator
    EqualityOpT equality_op;

    /// Total number of input items (i.e., length of `d_in`)
    OffsetT num_items;

    /// CUDA stream to launch kernels within. Default is stream<sub>0</sub>.
    cudaStream_t stream;

    int ptx_version;

    /**
     * @param d_temp_storage
     *   Device-accessible allocation of temporary storage.
     *   When `nullptr`, the required allocation size is written to `temp_storage_bytes`
     *   and no work is done.
     *
     * @param temp_storage_bytes
     *   Reference to size in bytes of `d_temp_storage` allocation
     *
     * @param d_in
     *   Pointer to the input sequence of data items
     *
     * @param d_flags
     *   Pointer to the input sequence of selection flags (if applicable)
     *
     * @param d_selected_out
     *   Pointer to the output sequence of selected data items
     *
     * @param d_num_selected_out
     *  Pointer to the total number of items selected (i.e., length of `d_selected_out`)
     *
     * @param select_op
     *   Selection operator
     *
     * @param equality_op
     *   Equality operator
     *
     * @param num_items
     *   Total number of input items (i.e., length of `d_in`)
     *
     * @param stream
     *   CUDA stream to launch kernels within. Default is stream<sub>0</sub>.
     */
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE DispatchSelectIf(void *d_temp_storage,
                                                          size_t &temp_storage_bytes,
                                                          InputIteratorT d_in,
                                                          FlagsInputIteratorT d_flags,
                                                          SelectedOutputIteratorT d_selected_out,
                                                          NumSelectedIteratorT d_num_selected_out,
                                                          SelectOpT select_op,
                                                          EqualityOpT equality_op,
                                                          OffsetT num_items,
                                                          cudaStream_t stream,
                                                          int ptx_version)
        : d_temp_storage(d_temp_storage)
        , temp_storage_bytes(temp_storage_bytes)
        , d_in(d_in)
        , d_flags(d_flags)
        , d_selected_out(d_selected_out)
        , d_num_selected_out(d_num_selected_out)
        , select_op(select_op)
        , equality_op(equality_op)
        , num_items(num_items)
        , stream(stream)
        , ptx_version(ptx_version)
    {}

    /******************************************************************************
     * Dispatch entrypoints
     ******************************************************************************/

    /**
     * Internal dispatch routine for computing a device-wide selection using the
     * specified kernel functions.
     */
    template <typename ActivePolicyT, typename ScanInitKernelPtrT, typename SelectIfKernelPtrT>
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE cudaError_t Invoke(ScanInitKernelPtrT scan_init_kernel,
                                                            SelectIfKernelPtrT select_if_kernel)
    {
      using Policy = typename ActivePolicyT::SelectIfPolicyT;

      using VsmemHelperT = cub::detail::vsmem_helper_default_fallback_policy_t<
        Policy,
        detail::agent_select_if_wrapper_t<KEEP_REJECTS>::template agent_t,
        InputIteratorT,
        FlagsInputIteratorT,
        SelectedOutputIteratorT,
        SelectOpT,
        EqualityOpT,
        OffsetT>;

      cudaError error = cudaSuccess;

      constexpr auto block_threads    = VsmemHelperT::agent_policy_t::BLOCK_THREADS;
      constexpr auto items_per_thread = VsmemHelperT::agent_policy_t::ITEMS_PER_THREAD;
      constexpr int tile_size         = block_threads * items_per_thread;
      int num_tiles                   = static_cast<int>(cub::DivideAndRoundUp(num_items, tile_size));
      const auto vsmem_size           = num_tiles * VsmemHelperT::vsmem_per_block;

      do
      {
        // Get device ordinal
        int device_ordinal;
        error = CubDebug(cudaGetDevice(&device_ordinal));
        if (cudaSuccess != error)
        {
          break;
        }

        // Specify temporary storage allocation requirements
        size_t allocation_sizes[2] = {0ULL, vsmem_size};

        // bytes needed for tile status descriptors
        error = CubDebug(ScanTileStateT::AllocationSize(num_tiles, allocation_sizes[0]));
        if (cudaSuccess != error)
        {
          break;
        }

        // Compute allocation pointers into the single storage blob (or compute the necessary size of the blob)
        void* allocations[2] = {};

        error = CubDebug(AliasTemporaries(d_temp_storage, temp_storage_bytes, allocations, allocation_sizes));
        if (cudaSuccess != error)
        {
          break;
        }

        if (d_temp_storage == nullptr)
        {
          // Return if the caller is simply requesting the size of the storage allocation
          break;
        }

        // Construct the tile status interface
        ScanTileStateT tile_status;
        error = CubDebug(tile_status.Init(num_tiles, allocations[0], allocation_sizes[0]));
        if (cudaSuccess != error)
        {
          break;
        }

        // Log scan_init_kernel configuration
        int init_grid_size = CUB_MAX(1, cub::DivideAndRoundUp(num_tiles, INIT_KERNEL_THREADS));

            #ifdef CUB_DETAIL_DEBUG_ENABLE_LOG
            _CubLog("Invoking scan_init_kernel<<<%d, %d, 0, %lld>>>()\n", init_grid_size, INIT_KERNEL_THREADS, (long long) stream);
            #endif

            // Invoke scan_init_kernel to initialize tile descriptors
            THRUST_NS_QUALIFIER::cuda_cub::launcher::triple_chevron(
                init_grid_size, INIT_KERNEL_THREADS, 0, stream
            ).doit(scan_init_kernel,
                tile_status,
                num_tiles,
                d_num_selected_out);

            // Check for failure to launch
            error = CubDebug(cudaPeekAtLastError());
            if (cudaSuccess != error)
            {
                break;
            }

            // Sync the stream if specified to flush runtime errors
            error = CubDebug(detail::DebugSyncStream(stream));
            if (cudaSuccess != error)
            {
              break;
            }

            // Return if empty problem
            if (num_items == 0)
            {
                break;
            }

            // Get max x-dimension of grid
            int max_dim_x;
            error = CubDebug(cudaDeviceGetAttribute(&max_dim_x, cudaDevAttrMaxGridDimX, device_ordinal));
            if (cudaSuccess != error)
            {
                break;
            }

            // Get grid size for scanning tiles
            dim3 scan_grid_size;
            scan_grid_size.z = 1;
            scan_grid_size.y = cub::DivideAndRoundUp(num_tiles, max_dim_x);
            scan_grid_size.x = CUB_MIN(num_tiles, max_dim_x);

            // Log select_if_kernel configuration
            #ifdef CUB_DETAIL_DEBUG_ENABLE_LOG
            {
              // Get SM occupancy for select_if_kernel
              int range_select_sm_occupancy;
              error = CubDebug(MaxSmOccupancy(range_select_sm_occupancy, // out
                                              select_if_kernel,
                                              block_threads));
              if (cudaSuccess != error)
              {
                break;
              }

              _CubLog("Invoking select_if_kernel<<<{%d,%d,%d}, %d, 0, "
                      "%lld>>>(), %d items per thread, %d SM occupancy\n",
                      scan_grid_size.x,
                      scan_grid_size.y,
                      scan_grid_size.z,
                      block_threads,
                      (long long)stream,
                      items_per_thread,
                      range_select_sm_occupancy);
            }
            #endif

            // Invoke select_if_kernel
            THRUST_NS_QUALIFIER::cuda_cub::launcher::triple_chevron(scan_grid_size, block_threads, 0, stream)
              .doit(select_if_kernel,
                    d_in,
                    d_flags,
                    d_selected_out,
                    d_num_selected_out,
                    tile_status,
                    select_op,
                    equality_op,
                    num_items,
                    num_tiles,
                    cub::detail::vsmem_t{allocations[1]});

            // Check for failure to launch
            error = CubDebug(cudaPeekAtLastError());
            if (cudaSuccess != error)
            {
                break;
            }

            // Sync the stream if specified to flush runtime errors
            error = CubDebug(detail::DebugSyncStream(stream));
            if (cudaSuccess != error)
            {
              break;
            }
        }
        while (0);

        return error;
    }

    template <typename ActivePolicyT>
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE cudaError_t Invoke()
    {
        using MaxPolicyT = typename SelectedPolicy::MaxPolicy;

        return Invoke<ActivePolicyT>(DeviceCompactInitKernel<ScanTileStateT, NumSelectedIteratorT>,
                                     DeviceSelectSweepKernel<MaxPolicyT,
                                                             InputIteratorT,
                                                             FlagsInputIteratorT,
                                                             SelectedOutputIteratorT,
                                                             NumSelectedIteratorT,
                                                             ScanTileStateT,
                                                             SelectOpT,
                                                             EqualityOpT,
                                                             OffsetT,
                                                             KEEP_REJECTS>);
    }

    /**
     * Internal dispatch routine
     *
     * @param d_temp_storage
     *   Device-accessible allocation of temporary storage.
     *   When `nullptr`, the required allocation size is written to `temp_storage_bytes`
     *   and no work is done.
     *
     * @param temp_storage_bytes
     *   Reference to size in bytes of `d_temp_storage` allocation
     *
     * @param d_in
     *   Pointer to the input sequence of data items
     *
     * @param d_flags
     *   Pointer to the input sequence of selection flags (if applicable)
     *
     * @param d_selected_out
     *   Pointer to the output sequence of selected data items
     *
     * @param d_num_selected_out
     *  Pointer to the total number of items selected (i.e., length of `d_selected_out`)
     *
     * @param select_op
     *   Selection operator
     *
     * @param equality_op
     *   Equality operator
     *
     * @param num_items
     *   Total number of input items (i.e., length of `d_in`)
     *
     * @param stream
     *   CUDA stream to launch kernels within. Default is stream<sub>0</sub>.
     */
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE static cudaError_t
    Dispatch(void *d_temp_storage,
             size_t &temp_storage_bytes,
             InputIteratorT d_in,
             FlagsInputIteratorT d_flags,
             SelectedOutputIteratorT d_selected_out,
             NumSelectedIteratorT d_num_selected_out,
             SelectOpT select_op,
             EqualityOpT equality_op,
             OffsetT num_items,
             cudaStream_t stream)
    {
        using MaxPolicyT = typename SelectedPolicy::MaxPolicy;

        int ptx_version = 0;
        if (cudaError_t error = CubDebug(PtxVersion(ptx_version)))
        {
            return error;
        }

        DispatchSelectIf dispatch(d_temp_storage,
                                    temp_storage_bytes,
                                    d_in,
                                    d_flags,
                                    d_selected_out,
                                    d_num_selected_out,
                                    select_op,
                                    equality_op,
                                    num_items,
                                    stream,
                                    ptx_version);

        return CubDebug(MaxPolicyT::Invoke(ptx_version, dispatch));
    }

    CUB_DETAIL_RUNTIME_DEBUG_SYNC_IS_NOT_SUPPORTED
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE
    static cudaError_t Dispatch(
        void*                       d_temp_storage,
        size_t&                     temp_storage_bytes,
        InputIteratorT              d_in,
        FlagsInputIteratorT         d_flags,
        SelectedOutputIteratorT     d_selected_out,
        NumSelectedIteratorT        d_num_selected_out,
        SelectOpT                   select_op,
        EqualityOpT                 equality_op,
        OffsetT                     num_items,
        cudaStream_t                stream,
        bool                        debug_synchronous)
    {
      CUB_DETAIL_RUNTIME_DEBUG_SYNC_USAGE_LOG

      return Dispatch(d_temp_storage,
                      temp_storage_bytes,
                      d_in,
                      d_flags,
                      d_selected_out,
                      d_num_selected_out,
                      select_op,
                      equality_op,
                      num_items,
                      stream);
    }
};


CUB_NAMESPACE_END
