/******************************************************************************
 * Copyright (c) 2024, Jay Shah, Ganesh Bikshandi, Ying Zhang, Vijay Thakkar, Pradeep Ramani, Tri Dao.
 ******************************************************************************/

#pragma once

#include "cute/atom/mma_atom.hpp"
#include "cutlass/gemm/collective/collective_builder.hpp"

#include "cutlass/cutlass.h"
#include "cutlass/layout/layout.h"
#include "cutlass/numeric_types.h"
#include "cutlass/pipeline/pipeline.hpp"

using namespace cute;

struct Flash_mask_params {
    void *__restrict__ q_ptr;
    void *__restrict__ k_ptr;
    void *__restrict__ v_ptr;
    void * __restrict__ o_ptr;
    int * __restrict__ cu_seq_q;
    int * __restrict__ cu_seq_k;
    int * __restrict__ mask;
    int * seq_len_encoder;
    int head_num;
    int kv_head_num;
    int max_seq_len_q;
    int max_seq_len_k;
    int batch_size;
    int gqa_group_size;
    float scale_softmax_log2;
};

template <int kStages, class Gemm1Type, class Gemm2Type, class OutputType, class SmemLayoutQ,
          class SmemLayoutK, class SmemLayoutV, class SmemLayoutO>
struct SharedStorageQKVO {
    cute::array_aligned<Gemm1Type, cute::cosize_v<SmemLayoutQ>> smem_q;
    cute::array_aligned<Gemm1Type, cute::cosize_v<SmemLayoutK>> smem_k;
    union {
        cute::array_aligned<Gemm2Type, cute::cosize_v<SmemLayoutV>> smem_v;
        cute::array_aligned<OutputType, cute::cosize_v<SmemLayoutO>> smem_o;
    };
    struct {
        cutlass::arch::ClusterTransactionBarrier barrier_Q;
        typename cutlass::PipelineTmaAsync<kStages>::SharedStorage pipeline_k;
        typename cutlass::PipelineTmaAsync<kStages>::SharedStorage pipeline_v;
    };
};

template<int kHeadDim_, int kBlockM_, int kBlockN_, int kNWarps_, int kStages_, bool NeedMask_, typename elem_type=cutlass::half_t>
struct Flash_mask_kernel_traits {
    using Element = elem_type;
    using ElementAccum = float;
    using index_t = int32_t;

    static constexpr int kNWarps = kNWarps_;
    static constexpr int kNThreads = kNWarps * cutlass::NumThreadsPerWarp;

    static constexpr int kBlockM = kBlockM_;
    static constexpr int kBlockN = kBlockN_;
    static constexpr int kHeadDim = kHeadDim_;
    static_assert(kHeadDim % 32 == 0);
    using TileShape_MNK = Shape<Int<kBlockM>, Int<kBlockN>, Int<kHeadDim>>;
    using ClusterShape_MNK = Shape<Int<1>, Int<1>, Int<1>>;
    static constexpr int kStages = kStages_;
    static constexpr int NeedMask = NeedMask_;

    using AtomLayoutMNK = Layout<Shape<Int<kBlockM / 64>, _1, _1>>;
    using TiledMma0 = decltype(cute::make_tiled_mma(
        cute::GMMA::ss_op_selector<Element, Element, ElementAccum, TileShape_MNK>(),
        AtomLayoutMNK{}));
    using TiledMma1 = decltype(cute::make_tiled_mma(
        cute::GMMA::rs_op_selector<Element, Element, ElementAccum, decltype(select<0, 2, 1>(TileShape_MNK{})),
            GMMA::Major::K, GMMA::Major::MN>(),
        AtomLayoutMNK{}));

    using SmemLayoutAtomQ = decltype(cutlass::gemm::collective::detail::ss_smem_selector<GMMA::Major::K, Element,
        decltype(cute::get<0>(TileShape_MNK{})), decltype(cute::get<2>(TileShape_MNK{}))>());
    using SmemLayoutQ = decltype(tile_to_shape(SmemLayoutAtomQ{}, select<0, 2>(TileShape_MNK{})));

    using SmemLayoutAtomK = decltype(cutlass::gemm::collective::detail::ss_smem_selector<GMMA::Major::K, Element,
        decltype(cute::get<1>(TileShape_MNK{})), decltype(cute::get<2>(TileShape_MNK{}))>());
    using SmemLayoutK =
        decltype(tile_to_shape(SmemLayoutAtomK{},
                 make_shape(shape<1>(TileShape_MNK{}), shape<2>(TileShape_MNK{}), Int<kStages>{})));

    using SmemLayoutAtomV = decltype(cutlass::gemm::collective::detail::ss_smem_selector<GMMA::Major::K, Element,
        decltype(cute::get<1>(TileShape_MNK{})), decltype(cute::get<2>(TileShape_MNK{}))>());
    using SmemLayoutV =
        decltype(tile_to_shape(SmemLayoutAtomV{},
                 make_shape(shape<1>(TileShape_MNK{}), shape<2>(TileShape_MNK{}), Int<kStages>{})));

    using SmemLayoutAtomO = decltype(cutlass::gemm::collective::detail::ss_smem_selector<GMMA::Major::K, Element,
        decltype(cute::get<0>(TileShape_MNK{})), decltype(cute::get<2>(TileShape_MNK{}))>());
    using SmemLayoutO = decltype(tile_to_shape(SmemLayoutAtomO{}, select<0, 2>(TileShape_MNK{})));

    using SmemCopyAtomQ = Copy_Atom<cute::SM75_U32x4_LDSM_N, Element>;
    using SmemCopyAtomO = Copy_Atom<cute::SM90_U32x4_STSM_N, Element>;

    using SharedStorage = SharedStorageQKVO<kStages, Element, Element, Element, SmemLayoutQ, SmemLayoutK, SmemLayoutV, SmemLayoutO>;

    static constexpr int NumProducerThreads = cutlass::NumThreadsPerWarpGroup;
    static constexpr int NumMmaThreads = kNThreads - NumProducerThreads;
    static constexpr int kNumVecElem = ceil_div(128, sizeof_bits_v<Element>);
    static constexpr int kNumThreadsPerRow = kHeadDim / kNumVecElem;
    static_assert(NumMmaThreads % kNumThreadsPerRow == 0);
    static constexpr int kNumRows = NumMmaThreads / kNumThreadsPerRow;
    using TiledCopyOAtom = cute::Copy_Atom<cute::UniversalCopy<cutlass::uint128_t>, Element>;
    using TiledCopyOThrLayout = decltype(cute::make_layout(
        cute::make_shape(Int<kNumRows>{}, Int<kNumThreadsPerRow>{}),
        LayoutRight{}));
    using TiledCopyOValLayout = decltype(cute::make_layout(
        cute::make_shape(_1{}, Int<kNumVecElem>{}),
        LayoutRight{}));
    using GmemTiledCopyO = decltype(make_tiled_copy(
        TiledCopyOAtom{},
        TiledCopyOThrLayout{},
        TiledCopyOValLayout{}
    ));

    using MainloopPipeline = typename cutlass::PipelineTmaAsync<kStages>;
    using PipelineState = typename cutlass::PipelineState<kStages>;
};
