// SPDX-License-Identifier: MIT
// Copyright (c) 2018-2025, Advanced Micro Devices, Inc. All rights reserved.

#pragma once

#include <iostream>
#include <string>

#include "ck_tile/core.hpp"
#include "ck_tile/ops/common.hpp"
#include "ck_tile/ops/gemm/pipeline/gemm_pipeline_ag_bg_cr_scheduler.hpp"

namespace ck_tile {

struct FlatmmProblem
{
    CK_TILE_HOST FlatmmProblem() = default;
    CK_TILE_HOST FlatmmProblem(
        index_t M_, index_t N_, index_t K_, index_t stride_A_, index_t stride_B_, index_t stride_C_)
        : M(M_), N(N_), K(K_), stride_A(stride_A_), stride_B(stride_B_), stride_C(stride_C_)
    {
    }

    index_t M;
    index_t N;
    index_t K;
    index_t stride_A;
    index_t stride_B;
    index_t stride_C;
};

struct FlatmmHostArgs : public FlatmmProblem
{
    CK_TILE_HOST FlatmmHostArgs() = default;
    CK_TILE_HOST FlatmmHostArgs(const void* a_ptr_,
                                const void* b_shuffle_ptr_,
                                void* c_ptr_,
                                index_t k_batch_,
                                index_t M_,
                                index_t N_,
                                index_t K_,
                                index_t stride_A_,
                                index_t stride_B_,
                                index_t stride_C_)
        : FlatmmProblem(M_, N_, K_, stride_A_, stride_B_, stride_C_),
          a_ptr(a_ptr_),
          b_shuffle_ptr(b_shuffle_ptr_),
          c_ptr(c_ptr_),
          k_batch(k_batch_)
    {
    }

    const void* a_ptr;
    const void* b_shuffle_ptr;
    void* c_ptr;
    index_t k_batch;
};

template <typename TilePartitioner_, typename FlatmmPipeline_, typename EpiloguePipeline_>
struct FlatmmKernel
{
    using TilePartitioner = remove_cvref_t<TilePartitioner_>;
    using FlatmmPipeline  = remove_cvref_t<FlatmmPipeline_>;
    using BlockGemmShape =
        remove_cvref_t<typename FlatmmPipeline::BlockGemmShape>; // TileFlatmmShape
    using EpiloguePipeline                   = remove_cvref_t<EpiloguePipeline_>;
    using ALayout                            = remove_cvref_t<typename FlatmmPipeline::ALayout>;
    using BLayout                            = remove_cvref_t<typename FlatmmPipeline::BLayout>;
    using CLayout                            = remove_cvref_t<typename FlatmmPipeline::CLayout>;
    static constexpr index_t KernelBlockSize = FlatmmPipeline::BlockSize;

    using ADataType = remove_cvref_t<typename FlatmmPipeline::ADataType>;
    using BDataType = remove_cvref_t<typename FlatmmPipeline::BDataType>;
    // Below type is actually accumulation data type - the output of block GEMM.
    using CDataType = remove_cvref_t<typename EpiloguePipeline::ODataType>;

    static constexpr auto I0   = number<0>();
    static constexpr auto I1   = number<1>();
    static constexpr auto I2   = number<2>();
    static constexpr auto idxM = I0;
    static constexpr auto idxN = I1;
    static constexpr auto idxK = I2;

    [[nodiscard]] CK_TILE_HOST static const std::string GetName()
    {
        // clang-format off
        return concat('_', "gemm", gemm_prec_str<ADataType, BDataType>, FlatmmPipeline::GetName());
        // clang-format on
    }

    CK_TILE_HOST static constexpr auto GridSize(index_t M, index_t N, index_t KBatch)
    {
        return dim3(TilePartitioner::GridSize(M, N), 1, KBatch);
    }

    CK_TILE_HOST static constexpr auto BlockSize() { return dim3(KernelBlockSize); }

    struct FlatmmKernelArgs
    {
        const void* a_ptr;
        const void* b_shuffle_ptr;
        void* c_ptr;
        index_t M;
        index_t N;
        index_t K;
        index_t stride_A;
        index_t stride_B;
        index_t stride_C;
        index_t k_batch;
    };

    CK_TILE_HOST static constexpr FlatmmKernelArgs MakeKernelArgs(const FlatmmHostArgs& hostArgs)
    {
        return FlatmmKernelArgs{hostArgs.a_ptr,
                                hostArgs.b_shuffle_ptr,
                                hostArgs.c_ptr,
                                hostArgs.M,
                                hostArgs.N,
                                hostArgs.K,
                                hostArgs.stride_A,
                                hostArgs.stride_B,
                                hostArgs.stride_C,
                                hostArgs.k_batch};
    }

    CK_TILE_HOST_DEVICE static constexpr index_t GetSmemSize()
    {
        return max(FlatmmPipeline::GetSmemSize(), EpiloguePipeline::GetSmemSize());
    }

    struct SplitKBatchOffset
    {
        __device__ SplitKBatchOffset(const FlatmmKernelArgs& kargs,
                                     const std::size_t k_id = blockIdx.z)
        {
            constexpr auto K1   = TilePartitioner::BlockGemmShape::WarpTile::at(number<2>{});
            const index_t K_t   = kargs.k_batch * K1;
            const index_t KRead = (kargs.K + K_t - 1) / K_t * K1;

            if constexpr(std::is_same_v<tensor_layout::gemm::RowMajor, ALayout>)
            {
                a_k_split_offset = k_id * KRead;
            }
            else if constexpr(std::is_same_v<tensor_layout::gemm::ColumnMajor, ALayout>)
            {
                a_k_split_offset = k_id * KRead * kargs.stride_A;
            }

            if constexpr(std::is_same_v<tensor_layout::gemm::RowMajor, BLayout>)
            {
                b_k_split_offset = k_id * KRead * kargs.stride_B;
            }
            else if constexpr(std::is_same_v<tensor_layout::gemm::ColumnMajor, BLayout>)
            {
                b_k_split_offset = k_id * KRead;
            }

            if(k_id < static_cast<uint32_t>(kargs.k_batch - 1))
            {
                splitted_k = KRead;
            }
            else
            {
                splitted_k = kargs.K - KRead * (kargs.k_batch - 1);
            }
        }

        index_t a_k_split_offset;
        index_t b_k_split_offset;
        index_t splitted_k;
    };

    CK_TILE_HOST static bool IsSupportedArgument(const FlatmmKernelArgs& kargs)
    {
        if constexpr(EpiloguePipeline::GetVectorSizeC() % 2 != 0 &&
                     is_any_of<CDataType, fp16_t, bf16_t>::value)
        {
            if(kargs.k_batch != 1)
            {
                std::cerr << "Conditions not met for Kbatch >1 !" << std::endl;
                return false;
            }
        }

        if constexpr(std::is_same_v<ALayout, tensor_layout::gemm::RowMajor>)
        {
            if(kargs.K % TilePartitioner::KPerBlock != 0 && FlatmmPipeline::kPadK == false)
            {
                std::cerr << "Can't support K that is not a multiple of KPerBlock"
                             " without padding!"
                          << std::endl;
                return false;
            }
            if(kargs.K % FlatmmPipeline::GetVectorSizeA() != 0)
            {
                std::cerr << "K is not a multiple of vector load size for A tensor!" << std::endl;
                return false;
            }
        }
        else
        {
            if(kargs.M % TilePartitioner::MPerBlock != 0 && FlatmmPipeline::kPadM == false)
            {
                std::cerr << "Can't support M that is not a multiple of MPerBlock"
                             " without padding!"
                          << std::endl;
                return false;
            }
            if(kargs.M % FlatmmPipeline::GetVectorSizeA() != 0)
            {
                std::cerr << "M is not a multiple of vector load size for A tensor!" << std::endl;
                return false;
            }
        }

        if constexpr(std::is_same_v<BLayout, tensor_layout::gemm::RowMajor>)
        {
            if(kargs.N % TilePartitioner::NPerBlock != 0 && FlatmmPipeline::kPadN == false)
            {
                std::cerr << "Can't support N that is not a multiple of NPerBlock"
                             " without padding!"
                          << std::endl;
                return false;
            }
            if(kargs.N % FlatmmPipeline::GetVectorSizeB() != 0)
            {
                std::cerr << "N is not a multiple of vector load size for B tensor!" << std::endl;
                return false;
            }
        }
        else
        {
            if(kargs.K % TilePartitioner::KPerBlock != 0 && FlatmmPipeline::kPadK == false)
            {
                std::cerr << "Can't support K that is not a multiple of KPerBlock"
                             " without padding!"
                          << std::endl;
                return false;
            }
            if(kargs.K % FlatmmPipeline::GetVectorSizeB() != 0)
            {
                std::cerr << "K is not a multiple of vector load size for B tensor!" << std::endl;
                return false;
            }
        }

        if constexpr(std::is_same_v<CLayout, tensor_layout::gemm::RowMajor>)
        {
            if(kargs.N % TilePartitioner::NPerBlock != 0 && FlatmmPipeline::kPadN == false)
            {
                std::cerr << "Can't support N that is not a multiple of NPerBlock"
                             " without padding!"
                          << std::endl;
                return false;
            }
            if(kargs.N % EpiloguePipeline::GetVectorSizeC() != 0)
            {
                std::cerr << "N is not a multiple of vector load size for C tensor!" << std::endl;
                return false;
            }
        }
        else
        {
            if(kargs.M % TilePartitioner::MPerBlock != 0 && FlatmmPipeline::kPadM == false)
            {
                std::cerr << "Can't support M that is not a multiple of MPerBlock"
                             " without padding!"
                          << std::endl;
                return false;
            }
            if(kargs.M % EpiloguePipeline::GetVectorSizeC() != 0)
            {
                std::cerr << "M is not a multiple of vector load size for C tensor!" << std::endl;
                return false;
            }
        }
        return true;
    }

    template <memory_operation_enum DstInMemOp = memory_operation_enum::set>
    CK_TILE_DEVICE static auto MakeGemmTensorViews(const ADataType* a_ptr,
                                                   const BDataType* b_flat_ptr,
                                                   CDataType* c_ptr,
                                                   const FlatmmKernelArgs& kargs,
                                                   const SplitKBatchOffset& splitk_batch_offset)
    {
        const auto& a_tensor_view = [&]() {
            if constexpr(std::is_same_v<ALayout, tensor_layout::gemm::RowMajor>)
            {
                return make_naive_tensor_view<address_space_enum::global>(
                    a_ptr,
                    make_tuple(kargs.M, splitk_batch_offset.splitted_k),
                    make_tuple(kargs.stride_A, 1),
                    number<FlatmmPipeline::GetVectorSizeA()>{},
                    number<1>{});
            }
            else
            {
                return make_naive_tensor_view<address_space_enum::global>(
                    a_ptr,
                    make_tuple(splitk_batch_offset.splitted_k, kargs.M),
                    make_tuple(kargs.stride_A, 1),
                    number<FlatmmPipeline::GetVectorSizeA()>{},
                    number<1>{});
            }
        }();

        index_t kFlatK = FlatmmPipeline::flatKPerWarp * (splitk_batch_offset.splitted_k /
                                                         BlockGemmShape::WarpTile::at(number<2>{}));
        index_t kFlatN = kargs.N * kargs.K / kFlatK;
        const auto& b_flat_tensor_view = [&]() {
            return make_naive_tensor_view<address_space_enum::global>(
                b_flat_ptr,
                make_tuple(kFlatN, kFlatK),
                make_tuple(kFlatK, 1),
                number<FlatmmPipeline::GetVectorSizeB()>{},
                number<1>{});
        }();

        // TODO: enable vector write for C in ColMajor
        const auto& c_tensor_view = [&]() {
            if constexpr(std::is_same_v<CLayout, tensor_layout::gemm::RowMajor>)
            {
                return make_naive_tensor_view<address_space_enum::global>(
                    c_ptr,
                    make_tuple(kargs.M, kargs.N),
                    make_tuple(kargs.stride_C, 1),
                    number<EpiloguePipeline::GetVectorSizeC()>{},
                    number<1>{});
            }
            else
            {
                return make_naive_tensor_view<address_space_enum::global>(
                    c_ptr,
                    make_tuple(kargs.M, kargs.N),
                    make_tuple(1, kargs.stride_C),
                    number<1>{},
                    number<1>{});
            }
        }();

        return make_tuple(a_tensor_view, b_flat_tensor_view, c_tensor_view);
    }

    template <typename TensorView>
    CK_TILE_DEVICE static auto MakeGemmPadViews(const TensorView& views)
    {
        const auto& a_pad_view = [&]() {
            const auto& a_tensor_view = views.at(I0);
            if constexpr(std::is_same_v<ALayout, tensor_layout::gemm::RowMajor>)
            {
                return pad_tensor_view(a_tensor_view,
                                       make_tuple(number<TilePartitioner::MPerBlock>{},
                                                  number<TilePartitioner::KPerBlock>{}),
                                       sequence<false, FlatmmPipeline::kPadK>{});
            }
            else
            {
                return pad_tensor_view(a_tensor_view,
                                       make_tuple(number<TilePartitioner::KPerBlock>{},
                                                  number<TilePartitioner::MPerBlock>{}),
                                       sequence<false, FlatmmPipeline::kPadM>{});
            }
        }();

        const auto& b_flat_tensor_view = views.at(I1);

        // TODO vector write in for C in ColMajor
        const auto& c_pad_view = [&]() {
            const auto& c_tensor_view = views.at(I2);
            if constexpr(std::is_same_v<CLayout, tensor_layout::gemm::RowMajor>)
            {
                return pad_tensor_view(c_tensor_view,
                                       make_tuple(number<TilePartitioner::MPerBlock>{},
                                                  number<TilePartitioner::NPerBlock>{}),
                                       sequence<false, FlatmmPipeline::kPadN>{});
            }
            else
            {
                return pad_tensor_view(c_tensor_view,
                                       make_tuple(number<TilePartitioner::MPerBlock>{},
                                                  number<TilePartitioner::NPerBlock>{}),
                                       sequence<FlatmmPipeline::kPadM, false>{});
            }
        }();

        return make_tuple(a_pad_view, b_flat_tensor_view, c_pad_view);
    }

    template <typename PadView>
    CK_TILE_DEVICE static auto
    MakeGemmTileWindows(const PadView& views, const index_t i_m, const index_t i_n)
    {
        const auto& a_pad_view      = views.at(I0);
        const auto& b_flat_pad_view = views.at(I1);
        const auto& c_pad_view      = views.at(I2);

        const auto& a_block_window = [&]() {
            if constexpr(std::is_same_v<ALayout, tensor_layout::gemm::RowMajor>)
            {
                return make_tile_window(a_pad_view,
                                        make_tuple(number<TilePartitioner::MPerBlock>{},
                                                   number<TilePartitioner::KPerBlock>{}),
                                        {i_m, 0});
            }
            else
            {
                return make_tile_window(a_pad_view,
                                        make_tuple(number<TilePartitioner::KPerBlock>{},
                                                   number<TilePartitioner::MPerBlock>{}),
                                        {0, i_m});
            }
        }();

        const auto& b_flat_block_window =
            make_tile_window(b_flat_pad_view,
                             make_tuple(number<FlatmmPipeline::flatNPerWarp>{},
                                        number<FlatmmPipeline::flatKPerWarp>{}),
                             {static_cast<int>(i_n / BlockGemmShape::WarpTile::at(idxN)), 0});

        auto c_block_window = make_tile_window(
            c_pad_view,
            make_tuple(number<TilePartitioner::MPerBlock>{}, number<TilePartitioner::NPerBlock>{}),
            {i_m, i_n});

        return make_tuple(a_block_window, b_flat_block_window, c_block_window);
    }

    CK_TILE_DEVICE static void RunFlatmm(const ADataType* a_ptr,
                                         const BDataType* b_flat_ptr,
                                         CDataType* c_ptr,
                                         void* smem_ptr,
                                         const FlatmmKernelArgs& kargs,
                                         const SplitKBatchOffset& splitk_batch_offset,
                                         const index_t block_idx_m,
                                         const index_t block_idx_n)
    {
        // Create Gemm tensor views, pad views and tile windows
        const auto& gemm_tensor_views_tuple =
            MakeGemmTensorViews<EpiloguePipeline::MemoryOperation>(
                a_ptr, b_flat_ptr, c_ptr, kargs, splitk_batch_offset);
        const auto& gemm_pad_views = MakeGemmPadViews(gemm_tensor_views_tuple);
        auto gemm_tile_windows     = MakeGemmTileWindows(gemm_pad_views, block_idx_m, block_idx_n);

        const index_t num_loop = TilePartitioner::GetLoopNum(splitk_batch_offset.splitted_k);

        // Run GEMM cooperatively by whole workgroup.
        const auto& a_block_window      = gemm_tile_windows.at(I0);
        const auto& b_flat_block_window = gemm_tile_windows.at(I1);
        const auto& c_block_tile        = FlatmmPipeline{}.template operator()(
            a_block_window, b_flat_block_window, num_loop, smem_ptr);

        // Run Epilogue Pipeline
        auto& c_block_window = gemm_tile_windows.at(I2);

        EpiloguePipeline{}.template operator()<decltype(c_block_window), decltype(c_block_tile)>(
            c_block_window, c_block_tile, smem_ptr);
    }

    CK_TILE_DEVICE void operator()(FlatmmKernelArgs kargs) const
    {
        const auto [iM, iN] = TilePartitioner{kargs.M, kargs.N}.GetOutputTileIndex(blockIdx.x);
        const index_t i_m   = __builtin_amdgcn_readfirstlane(iM * TilePartitioner::MPerBlock);
        const index_t i_n   = __builtin_amdgcn_readfirstlane(iN * TilePartitioner::NPerBlock);

        const SplitKBatchOffset splitk_batch_offset(kargs);
        // options
        const ADataType* a_ptr =
            static_cast<const ADataType*>(kargs.a_ptr) + splitk_batch_offset.a_k_split_offset;
        const BDataType* b_flat_ptr = static_cast<const BDataType*>(kargs.b_shuffle_ptr) +
                                      splitk_batch_offset.b_k_split_offset;
        CDataType* c_ptr = static_cast<CDataType*>(kargs.c_ptr);

        // allocate LDS
        __shared__ char smem_ptr[GetSmemSize()];

        if constexpr(!(EpiloguePipeline::MemoryOperation == memory_operation_enum::atomic_add &&
                       EpiloguePipeline::GetVectorSizeC() % 2 != 0 &&
                       is_any_of<CDataType, fp16_t, bf16_t>::value))
        {
            RunFlatmm(a_ptr, b_flat_ptr, c_ptr, smem_ptr, kargs, splitk_batch_offset, i_m, i_n);
        }
    }
};

} // namespace ck_tile