/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015-2022 Advanced Micro Devices, Inc. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#ifndef MIGRAPHX_GUARD_KERNELS_INDEX_HPP
#define MIGRAPHX_GUARD_KERNELS_INDEX_HPP

#include <migraphx/kernels/hip.hpp>
#include <migraphx/kernels/types.hpp>
#include <migraphx/kernels/integral_constant.hpp>
#include <migraphx/kernels/type_traits.hpp>
#include <migraphx/kernels/debug.hpp>
#include <migraphx/kernels/functional.hpp>

namespace migraphx {

#if defined(MIGRAPHX_NGLOBAL) && defined(MIGRAPHX_NLOCAL)
#define MIGRAPHX_NGROUP ((MIGRAPHX_NGLOBAL + MIGRAPHX_NLOCAL - 1) / MIGRAPHX_NLOCAL)
#endif

inline __device__ __attribute__((const)) index_int compute_global_size()
{
#ifdef MIGRAPHX_NGLOBAL
    return MIGRAPHX_NGLOBAL;
#else
    // This actualy works even when global is not divisible by local size.
    // This doesnt actually do a multiplicatiosn. Instead it calls a device
    // function to get the global size, which is why it works.
    return blockDim.x * gridDim.x;  // NOLINT
#endif
}

// We cant just use blockDim.x to get the local size since its broken on hip
// when global is not divisible by local size. In this case, we calulate the
// size for the last group.
inline __device__ __attribute__((const)) index_int compute_local_size()
{
#ifdef MIGRAPHX_NLOCAL
    const auto nlocal = MIGRAPHX_NLOCAL;
#else
    const auto nlocal = blockDim.x; // NOLINT
#endif
#ifdef MIGRAPHX_NGROUP
    const auto ngroup = MIGRAPHX_NGROUP;
#else
    const auto ngroup = gridDim.x;  // NOLINT
#endif
    const auto group_id = blockIdx.x; // NOLINT
    const auto nglobal  = compute_global_size();
    if(group_id == ngroup - 1)
    {
        return 1 + (nglobal - 1) % nlocal;
    }
    else
    {
        return nlocal; // NOLINT
    }
}

#ifdef MIGRAPHX_NGROUP
// If global is divisible by local then local can be a const
#if(MIGRAPHX_NGLOBAL % MIGRAPHX_NLOCAL == 0) || (MIGRAPHX_NGROUP == 1)
#define MIGRAPHX_HAS_CONST_LOCAL 1
#endif
#endif

struct index
{
    index_int global = 0;
    index_int local  = 0;
    index_int group  = 0;

#ifdef MIGRAPHX_NGLOBAL
    constexpr index_constant<MIGRAPHX_NGLOBAL> nglobal() const
    {
        static_assert(MIGRAPHX_NGLOBAL > 0, "Global size must be greater than 0");
        return {};
    }
#else
    __device__ index_int nglobal() const
    {
        MIGRAPHX_ASSERT(compute_global_size() > 0);
        return compute_global_size(); // NOLINT
    }
#endif

#ifdef MIGRAPHX_HAS_CONST_LOCAL
    constexpr index_constant<MIGRAPHX_NLOCAL> nlocal() const
    {
        static_assert(MIGRAPHX_NLOCAL > 0, "Local size must be greater than 0");
        return {};
    }
#else
    __device__ index_int nlocal() const
    {
#ifdef MIGRAPHX_NGROUP
        static_assert((MIGRAPHX_NGLOBAL % MIGRAPHX_NLOCAL != 0) and (MIGRAPHX_NGROUP > 1),
                      "Local size should be const");
#endif
        MIGRAPHX_ASSERT(compute_local_size() > 0);
        return compute_local_size(); // NOLINT
    }
#endif

#ifdef MIGRAPHX_NLOCAL
    constexpr index_constant<MIGRAPHX_NLOCAL> max_nlocal() const { return {}; }
#else
    __device__ index_int max_nlocal() const
    {
        MIGRAPHX_ASSERT(blockDim.x > 0);
        return blockDim.x;
    }
#endif
    template <class N, class Stride>
    static constexpr auto max_stride_iterations(N n, Stride stride)
    {
        return (n - _c<1>) / stride + _c<1>;
    }

    template <class N>
    constexpr auto max_global_stride_iterations(N n) const
    {
        return max_stride_iterations(n, nglobal());
    }

    template <class N>
    constexpr auto max_local_stride_iterations(N n) const
    {
        return max_stride_iterations(n, nlocal());
    }

    template <class F, class I, class D>
    static constexpr auto invoke_loop(F f, I i, D d) -> decltype(f(i, d))
    {
        return f(i, d);
    }

    template <class F, class I, class D>
    static constexpr auto invoke_loop(F f, I i, D) -> decltype(f(i))
    {
        return f(i);
    }

    template <class F, class N, class Stride>
    static constexpr void for_stride_loop_unroll(index_int start, N n, Stride stride, F f)
    {
        sequence(max_stride_iterations(n, stride), [&](auto... ks) {
            fold([&](auto d, auto k) {
                auto i = start + stride * k;
                if(i < n)
                    invoke_loop(f, i, d);
                return d + _c<1>;
            })(_c<0>, ks...);
        });
    }

    template <class F, class N, class Stride>
    static constexpr void for_stride_loop(index_int start, N n, Stride stride, F f)
    {
        index_int k = 0;
        for(index_int i = start; i < n; i += stride)
        {
            invoke_loop(f, i, k);
            k++;
        }
    }

    template <bool Unroll, class F, class N, class Stride>
    static constexpr void for_stride(index_int start, N n, Stride stride, F f)
    {
        MIGRAPHX_ASSERT(start < stride);
        if constexpr(not is_integral<N>{} and not is_integral<Stride>{})
        {
            if constexpr(max_stride_iterations(n, stride) == 1)
            {
                if constexpr(stride > n)
                {
                    if(start < n)
                        invoke_loop(f, start, _c<0>);
                }
                else
                {
                    invoke_loop(f, start, _c<0>);
                }
            }
            else if constexpr(Unroll)
            {
                MIGRAPHX_STATIC_ASSERT_FOR(max_stride_iterations(n, stride) < 256)
                {
                    for_stride_loop_unroll(start, n, stride, f);
                }
            }
            else
            {
                for_stride_loop(start, n, stride, f);
            }
        }
        else
        {
            for_stride_loop(start, n, stride, f);
        }
    }

    template <class F, class N>
    __device__ void global_stride(N n, F f) const
    {
        for_stride<false>(global, n, nglobal(), f);
    }

    template <class F, class N>
    __device__ void local_stride(N n, F f) const
    {
        for_stride<true>(local, n, nlocal(), f);
    }
};

inline __device__ __attribute__((const)) index make_index()
{
    return index{blockIdx.x * blockDim.x + threadIdx.x, threadIdx.x, blockIdx.x}; // NOLINT
}

} // namespace migraphx
#endif // MIGRAPHX_GUARD_KERNELS_INDEX_HPP
