// Adapted from
// https://github.com/NVIDIA/TensorRT-LLM/blob/be1788106245496872d18e702978e59b6bfd50e0/cpp/tensorrt_llm/cutlass_extensions/include/cutlass_extensions/gemm/device/gemm_universal_base_compat.h
#pragma once

#include <cutlass/cutlass.h>
#include <cutlass/device_kernel.h>
#include <cutlass/trace.h>

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

namespace cutlass {
namespace gemm {
namespace device {

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

/*
    This is the device layer from CUTLASS 2.10 (SHA - cc85b64cf676c45f98a17e3a47c0aafcf817f088)
    It is replicated here since we needed to duplicate kernel level APIs for mixed dtype GEMMs
    and SmoothQuant. The newer device layer is not compatible with these older kernel level APIs.

    Note: While CUTLASS 3.x supports stream-k, none of the kernels in the extensions folder support
          that feature at the moment.
  */

template <typename GemmKernel_>
class GemmUniversalBaseCompat {
 public:
  using GemmKernel = GemmKernel_;
  using ThreadblockShape = typename GemmKernel::Mma::Shape;

  using ElementA = typename GemmKernel::ElementA;
  using LayoutA = typename GemmKernel::LayoutA;
  using TensorRefA = TensorRef<ElementA const, LayoutA>;
  static ComplexTransform const kTransformA = GemmKernel::kTransformA;

  using ElementB = typename GemmKernel::ElementB;
  using LayoutB = typename GemmKernel::LayoutB;
  using TensorRefB = TensorRef<ElementB const, LayoutB>;
  static ComplexTransform const kTransformB = GemmKernel::kTransformB;

  using ElementC = typename GemmKernel::ElementC;
  using LayoutC = typename GemmKernel::LayoutC;
  using TensorRefC = TensorRef<ElementC const, LayoutC>;
  using TensorRefD = TensorRef<ElementC, LayoutC>;

  using ElementAccumulator = typename GemmKernel::Mma::Policy::Operator::ElementC;

  using EpilogueOutputOp = typename GemmKernel::EpilogueOutputOp;
  using ThreadblockSwizzle = typename GemmKernel::ThreadblockSwizzle;
  using Operator = typename GemmKernel::Operator;

  /// Argument structure
  using Arguments = typename GemmKernel::Arguments;

 protected:
  /// Kernel parameters object
  typename GemmKernel::Params params_;

 protected:
  /// Private helper to obtain the grid dimensions with fix-up for split-K
  static void get_grid_shape_(gemm::GemmCoord& grid_tiled_shape, int& gemm_k_size, Arguments const& args) {
    // Determine grid shape
    ThreadblockSwizzle threadblock_swizzle;

    grid_tiled_shape = threadblock_swizzle.get_tiled_shape(
        args.problem_size, {ThreadblockShape::kM, ThreadblockShape::kN, ThreadblockShape::kK}, args.batch_count);

    gemm_k_size = args.problem_size.k();

    if (args.mode == GemmUniversalMode::kGemm || args.mode == GemmUniversalMode::kGemmSplitKParallel) {
      int const kAlignK =
          const_max(const_max(128 / sizeof_bits<ElementA>::value, 128 / sizeof_bits<ElementB>::value), 1);

      gemm_k_size = round_up(ceil_div(args.problem_size.k(), args.batch_count), kAlignK);

      if (gemm_k_size) {
        grid_tiled_shape.k() = ceil_div(args.problem_size.k(), gemm_k_size);
      }
    }
  }

 public:
  /// Constructs the GEMM.
  GemmUniversalBaseCompat() {}

  /// Determines whether the GEMM can execute the given problem.
  static Status can_implement(Arguments const& args) {
    // Determine grid shape
    cutlass::gemm::GemmCoord grid_tiled_shape;
    int gemm_k_size = 0;

    get_grid_shape_(grid_tiled_shape, gemm_k_size, args);

    ThreadblockSwizzle threadblock_swizzle;
    dim3 grid = threadblock_swizzle.get_grid_shape(grid_tiled_shape);

    uint32_t const kGridYZMax = ((1 << (sizeof(uint16_t) * 8)) - 1);

    if (!(grid.y <= kGridYZMax && grid.z <= kGridYZMax)) {
      return Status::kErrorInvalidProblem;
    }

    return GemmKernel::can_implement(args);
  }

  /// Gets the workspace size
  static size_t get_workspace_size(Arguments const& args) {
    CUTLASS_TRACE_HOST("GemmUniversalBaseCompat::get_workspace_size()");

    size_t workspace_bytes = 0;

    // Determine grid shape
    cutlass::gemm::GemmCoord grid_tiled_shape;
    int gemm_k_size = 0;

    get_grid_shape_(grid_tiled_shape, gemm_k_size, args);

    if (args.mode == GemmUniversalMode::kGemmSplitKParallel) {
      // Split-K parallel always requires a temporary workspace
      workspace_bytes = sizeof(ElementC) * size_t(args.batch_stride_D) * size_t(grid_tiled_shape.k());
    } else if (args.mode == GemmUniversalMode::kGemm && grid_tiled_shape.k() > 1) {
      // Serial split-K only requires a temporary workspace if the number of partitions along the
      // GEMM K dimension is greater than one.
      workspace_bytes = sizeof(int) * size_t(grid_tiled_shape.m()) * size_t(grid_tiled_shape.n());
    }

    CUTLASS_TRACE_HOST("  workspace_bytes: " << workspace_bytes);

    workspace_bytes += GemmKernel::get_extra_workspace_size(args, grid_tiled_shape);

    return workspace_bytes;
  }

  /// Computes the grid shape
  static dim3 get_grid_shape(Arguments const& args) {
    CUTLASS_TRACE_HOST("GemmUniversalBaseCompat::get_grid_shape()");

    ThreadblockSwizzle threadblock_swizzle;

    cutlass::gemm::GemmCoord grid_tiled_shape;
    int gemm_k_size = 0;

    get_grid_shape_(grid_tiled_shape, gemm_k_size, args);
    dim3 result = threadblock_swizzle.get_grid_shape(grid_tiled_shape);

    CUTLASS_TRACE_HOST("  grid_tiled_shape: " << grid_tiled_shape << "\n"
                                              << "  result = {" << result << "}");

    return result;
  }

  /// Computes the maximum number of active blocks per multiprocessor
  static int maximum_active_blocks(int smem_capacity = -1) {
    CUTLASS_TRACE_HOST("GemmUniversalBaseCompat::maximum_active_blocks()");

    int max_active_blocks = -1;
    int smem_size = int(sizeof(typename GemmKernel::SharedStorage));

    CUTLASS_TRACE_HOST("  smem_size: " << smem_size << " bytes");

    if (smem_size <= (48 << 10)) {
      cudaError_t result = cudaOccupancyMaxActiveBlocksPerMultiprocessor(&max_active_blocks, Kernel<GemmKernel>,
                                                                         GemmKernel::kThreadCount, smem_size);

      if (result == cudaSuccess) {
        CUTLASS_TRACE_HOST("  max_active_blocks: " << max_active_blocks);
        return max_active_blocks;
      }
    } else {
      // Query assuming zero shared memory then compute occupancy limit based on SMEM
      cudaError_t result = cudaOccupancyMaxActiveBlocksPerMultiprocessor(&max_active_blocks, Kernel<GemmKernel>,
                                                                         GemmKernel::kThreadCount, 0);

      if (result != cudaSuccess) {
        CUTLASS_TRACE_HOST("  cudaOccupancyMaxActiveBlocksPerMultiprocessor() returned error "
                           << cudaGetErrorString(result));

        return -1;
      }

      if (smem_capacity < 0) {
        int device_idx = 0;
        result = cudaGetDevice(&device_idx);

        if (result != cudaSuccess) {
          return -1;
        }

        cudaDeviceProp properties;
        result = cudaGetDeviceProperties(&properties, device_idx);

        if (result != cudaSuccess) {
          return -1;
        }

        smem_capacity = static_cast<int>(properties.sharedMemPerMultiprocessor);
      }

      int occupancy = std::min(max_active_blocks, smem_capacity / smem_size);

      CUTLASS_TRACE_HOST("  occupancy: " << occupancy);

      return occupancy;
    }

    CUTLASS_TRACE_HOST("  returning internal error");

    return -1;
  }

  /// Initializes GEMM state from arguments.
  Status initialize(Arguments const& args, void* workspace = nullptr, cudaStream_t stream = nullptr) {
    CUTLASS_TRACE_HOST("GemmUniversalBaseCompat::initialize() - workspace "
                       << workspace << ", stream: " << (stream ? "non-null" : "null"));

    size_t workspace_bytes = get_workspace_size(args);

    CUTLASS_TRACE_HOST("  workspace_bytes: " << workspace_bytes);

    if (workspace_bytes) {
      if (!workspace) {
        CUTLASS_TRACE_HOST("  error: device workspace must not be null");

        return Status::kErrorWorkspaceNull;
      }

      if (args.mode == GemmUniversalMode::kGemm) {
        CUTLASS_TRACE_HOST("  clearing device workspace");
        cudaError_t result = cudaMemsetAsync(workspace, 0, workspace_bytes, stream);

        if (result != cudaSuccess) {
          CUTLASS_TRACE_HOST("  cudaMemsetAsync() returned error " << cudaGetErrorString(result));

          return Status::kErrorInternal;
        }
      }
    }

    // Get CUDA grid shape
    cutlass::gemm::GemmCoord grid_tiled_shape;
    int gemm_k_size = 0;

    get_grid_shape_(grid_tiled_shape, gemm_k_size, args);

    // Initialize the Params structure
    params_ = typename GemmKernel::Params(args, grid_tiled_shape, gemm_k_size, static_cast<int*>(workspace));

    // Specify shared memory capacity for kernel.
    int smem_size = int(sizeof(typename GemmKernel::SharedStorage));

    if (smem_size >= (48 << 10)) {
      cudaError_t result =
          cudaFuncSetAttribute(Kernel<GemmKernel>, cudaFuncAttributeMaxDynamicSharedMemorySize, smem_size);

      if (result != cudaSuccess) {
        return Status::kErrorInternal;
      }
    }

    return Status::kSuccess;
  }

  /// Lightweight update given a subset of arguments
  Status update(Arguments const& args, void* workspace = nullptr) {
    CUTLASS_TRACE_HOST("GemmUniversalBaseCompat()::update() - workspace: " << workspace);

    size_t workspace_bytes = get_workspace_size(args);

    if (workspace_bytes && !workspace) {
      return Status::kErrorWorkspaceNull;
    }

    params_.update(args, workspace);

    return Status::kSuccess;
  }

  /// Runs the kernel using initialized state.
  Status run(cudaStream_t stream = nullptr) {
    CUTLASS_TRACE_HOST("GemmUniversalBaseCompat::run()");

    //
    // Configure grid and block dimensions
    //

    ThreadblockSwizzle threadblock_swizzle;

    dim3 grid = threadblock_swizzle.get_grid_shape(params_.grid_tiled_shape);
    dim3 block(GemmKernel::kThreadCount, 1, 1);

    int smem_size = int(sizeof(typename GemmKernel::SharedStorage));

    //
    // Launch kernel
    //

    CUTLASS_TRACE_HOST("  grid: (" << grid << "),  block: (" << block << "),  SMEM: " << smem_size << " bytes");

    // Launch
    cutlass::Kernel<GemmKernel><<<grid, block, smem_size, stream>>>(params_);

    //
    // Query for errors
    //
    cudaError_t result = cudaGetLastError();

    if (result != cudaSuccess) {
      CUTLASS_TRACE_HOST("  grid launch failed with error " << cudaGetErrorString(result));
      return Status::kErrorInternal;
    }

    return Status::kSuccess;
  }

  /// Runs the kernel using initialized state.
  Status operator()(cudaStream_t stream = nullptr) {
    return run(stream);
  }

  /// Runs the kernel using initialized state.
  Status operator()(Arguments const& args, void* workspace = nullptr, cudaStream_t stream = nullptr) {
    Status status = initialize(args, workspace, stream);

    if (status == Status::kSuccess) {
      status = run(stream);
    }

    return status;
  }
};

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

}  // namespace device
}  // namespace gemm
}  // namespace cutlass

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