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/*! \file
    \brief Scheduler for grouped FMHA
*/

#pragma once

#include "cutlass/cutlass.h"
#include "cutlass/gemm/gemm.h"
#include "cutlass/matrix_coord.h"
#include "cutlass/gemm/kernel/grouped_problem_visitor.h"

/////////////////////////////////////////////////////////////////////////////////////////////////

namespace cutlass {
namespace gemm {
namespace kernel {

/////////////////////////////////////////////////////////////////////////////////////////////////

namespace detail {
// Helper for correctly representing problem sizes in grouped kernels
template <typename ThreadblockShape>
struct FMHAGroupedProblemSizeHelper {

  CUTLASS_HOST_DEVICE
  static cutlass::gemm::GemmCoord grid_shape(const cutlass::gemm::GemmCoord& problem) {
    // FMHA only partitions tiles across the M dimension.
    return cutlass::gemm::GemmCoord(
      ((problem.m() - 1 + ThreadblockShape::kM) / ThreadblockShape::kM), 1, 1);
  }

  CUTLASS_HOST_DEVICE
  static void possibly_transpose_problem(cutlass::gemm::GemmCoord& problem) {}

  CUTLASS_HOST_DEVICE
  static int32_t tile_count(const cutlass::gemm::GemmCoord& grid) {
    return grid.m() * grid.n();
  }
};

} // namespace detail

/// Visitor class to abstract away the algorithm for iterating over tiles
template <typename ThreadblockShape,
          GroupScheduleMode GroupScheduleMode_,
          int PrefetchTileCount,
          int ThreadCount,
          bool Transposed = false>
struct FMHAGroupedProblemVisitor : public GroupedProblemVisitor<
                                            detail::FMHAGroupedProblemSizeHelper<ThreadblockShape>,
                                            ThreadblockShape,
                                            GroupScheduleMode_,
                                            PrefetchTileCount,
                                            ThreadCount> {

  using ProblemSizeHelper = detail::FMHAGroupedProblemSizeHelper<ThreadblockShape>;
  using Base = GroupedProblemVisitor<ProblemSizeHelper, ThreadblockShape, GroupScheduleMode_, PrefetchTileCount, ThreadCount>;
  using BaseParams = typename Base::Params;
  using SharedStorage = typename Base::SharedStorage;

  cutlass::gemm::GemmCoord const *problem_sizes0;
  cutlass::gemm::GemmCoord const *problem_sizes1;

  struct Params {
    cutlass::gemm::GemmCoord const *problem_sizes0;
    cutlass::gemm::GemmCoord const *problem_sizes1;
    int32_t                         problem_count;
    void const                     *workspace;
    int32_t                         tile_count;

    //
    // Methods
    //

    /// Ctor
    CUTLASS_HOST_DEVICE
    Params(): problem_sizes0(nullptr), problem_sizes1(nullptr),
              problem_count(0), workspace(nullptr), tile_count(0) { }

    /// Ctor
    CUTLASS_HOST_DEVICE
    Params(
      cutlass::gemm::GemmCoord const *problem_sizes0,
      cutlass::gemm::GemmCoord const *problem_sizes1,
      int32_t                         problem_count,
      void const                     *workspace = nullptr,
      int32_t                         tile_count = 0
    ):
      problem_sizes0(problem_sizes0),
      problem_sizes1(problem_sizes1),
      problem_count(problem_count),
      workspace(workspace),
      tile_count(tile_count)
    {}

    /// Convert the FMHA-specific parameters to those used by the base class
    CUTLASS_HOST_DEVICE
    BaseParams to_base() const {
        return BaseParams(// Set problem_sizes as problem_sizes1 because these determine
                          // shape of the final output of FMHA
                          problem_sizes1,
                          problem_count,
                          workspace,
                          tile_count);
    }

  };

  //
  // Methods
  //
  CUTLASS_DEVICE
  FMHAGroupedProblemVisitor(
    Params const &params_,
    SharedStorage &shared_storage_, 
    int32_t block_idx
  ): Base (
        params_.to_base(),
        shared_storage_, block_idx),
     problem_sizes0(params_.problem_sizes0),
     problem_sizes1(params_.problem_sizes1)
  {}

  /// Returns the problem size 0 for the current problem
  CUTLASS_HOST_DEVICE
  cutlass::gemm::GemmCoord problem_size0() const {
    GemmCoord problem = problem_sizes0[this->problem_idx];
    ProblemSizeHelper::possibly_transpose_problem(problem);
    return problem;
  }

  /// Returns the problem size 1 for the current problem
  CUTLASS_HOST_DEVICE
  cutlass::gemm::GemmCoord problem_size1() const {
    GemmCoord problem = problem_sizes1[this->problem_idx];
    ProblemSizeHelper::possibly_transpose_problem(problem);
    return problem;
  }
};

/////////////////////////////////////////////////////////////////////////////////////////////////

} // namespace kernel
} // namespace gemm
} // namespace cutlass

/////////////////////////////////////////////////////////////////////////////////////////////////
