/*
 * SPDX-FileCopyrightText: Copyright (c) 2023-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#ifndef GENERATE_CUBIN
#include <cassert>
#include <cstdint>
#include <cstdio>
#include <cuda.h>
#include <cuda_runtime_api.h>
#include <stdexcept>
#endif
#include "mha_stdheaders.cuh"

template <typename T>
HOST_DEVICE_FUNC constexpr inline void unused(T&& x)
{
    static_cast<void>(x);
}

#ifndef GENERATE_CUBIN
inline void checkCuda(cudaError_t err)
{
    if (err != cudaSuccess)
    {
        printf("%s\n", cudaGetErrorName(err));
        throw std::runtime_error(cudaGetErrorName(err));
    }
}

inline void checkCu(CUresult err)
{
    if (err != CUDA_SUCCESS)
    {
        char const* str = nullptr;
        if (cuGetErrorName(err, &str) != CUDA_SUCCESS)
        {
            str = "A cuda driver API error happened, but we failed to query the error name\n";
        }
        printf("%s\n", str);
        throw std::runtime_error(str);
    }
}
#endif

HOST_DEVICE_FUNC constexpr inline uint32_t greatestPowerOf2Divisor(uint32_t x)
{
    return x & ~(x - 1);
}

template <typename T>
HOST_DEVICE_FUNC constexpr uint32_t maxArrayAlign(uint32_t size)
{
    return sizeof(T) * greatestPowerOf2Divisor(size);
}

HOST_DEVICE_FUNC constexpr inline uint32_t exactDiv(uint32_t a, uint32_t b)
{
    assert(a % b == 0);
    return a / b;
}

template <typename T>
HOST_DEVICE_FUNC constexpr inline T divUp(T a, T b)
{
    return (a + b - 1) / b;
}

template <typename T>
HOST_DEVICE_FUNC constexpr inline T roundUp(T a, T b)
{
    return divUp(a, b) * b;
}

// upperBound is exclusive, i.e. range is [0, upperBound)
template <uint32_t upperBound>
struct BoundedVal
{
    template <uint32_t divisor>
    HOST_DEVICE_FUNC inline BoundedVal<upperBound / divisor> divBy() const
    {
        assert(value < upperBound);
        return {upperBound <= divisor ? 0 : value / divisor};
    }

    template <uint32_t divisor>
    HOST_DEVICE_FUNC inline BoundedVal<mha::min(divisor, upperBound)> mod() const
    {
        assert(value < upperBound);
        return {upperBound <= divisor ? value : value % divisor};
    }

    HOST_DEVICE_FUNC inline bool operator<=(uint32_t rhs) const
    {
        assert(value < upperBound);
        return upperBound <= rhs || value <= rhs;
    }

    HOST_DEVICE_FUNC inline uint32_t get() const
    {
        assert(value < upperBound);
        return upperBound == 1 ? 0 : value;
    }

    uint32_t value;
};

template <typename T, uint32_t size_>
struct alignas(mha::max<uint32_t>(alignof(T), mha::min<uint32_t>(maxArrayAlign<T>(size_), 16))) Vec
{
    using Elem = T;
    static constexpr uint32_t size = size_;
    Elem data[size];

    HOST_DEVICE_FUNC inline void fill(T val)
    {
#pragma unroll
        for (uint32_t i = 0; i < size; i++)
        {
            data[i] = val;
        }
    }

    static HOST_DEVICE_FUNC inline Vec<T, size> filled(T val)
    {
        Vec<T, size> ret;
        ret.fill(val);
        return ret;
    }

    HOST_DEVICE_FUNC inline Elem const& operator[](uint32_t i) const
    {
        assert(i < size);
        return data[BoundedVal<size>{i}.get()];
    }

    HOST_DEVICE_FUNC inline Elem& operator[](uint32_t i)
    {
        assert(i < size);
        return data[BoundedVal<size>{i}.get()];
    }
};

template <uint32_t nbBuffers_>
struct CircIdx
{
public:
    static constexpr uint32_t nbBuffers = nbBuffers_;
    static_assert(nbBuffers >= 1);

    __device__ inline CircIdx(uint32_t init)
        : mIndex{init % nbBuffers}
    {
    }

    __device__ inline operator uint32_t() const
    {
        return mIndex;
    }

    __device__ inline CircIdx operator+(uint32_t i) const
    {
        return CircIdx{(mIndex + i) % nbBuffers};
    }

    __device__ inline CircIdx operator-(uint32_t i) const
    {
        return CircIdx{(mIndex + (nbBuffers - 1) * i) % nbBuffers};
    }

    __device__ inline CircIdx next() const
    {
        return *this + 1u;
    }

    __device__ inline CircIdx& operator++()
    {
        mIndex = next();
        return *this;
    }

    __device__ inline CircIdx operator++(int)
    {
        CircIdx old = *this;
        operator++();
        return old;
    }

    __device__ inline CircIdx prev() const
    {
        return *this - 1u;
    }

    __device__ inline CircIdx& operator--()
    {
        mIndex = prev();
        return *this;
    }

    __device__ inline CircIdx operator--(int)
    {
        CircIdx old = *this;
        operator--();
        return old;
    }

private:
    uint32_t mIndex;
};

// base is usually in constant memory, so usually only require 1 register to store the offset.
template <typename T>
struct TinyPtr
{
    T* base;         // typically in constant memory or uniform registers
    uint32_t offset; // may be non-uniform

    template <typename D>
    __device__ __host__ inline TinyPtr<D> cast() const
    {
        D* const p = reinterpret_cast<D*>(base);
        assert(reinterpret_cast<uintptr_t>(p) % alignof(D) == 0);
        if constexpr (mha::is_void_v<T>)
        {
            assert(offset == 0);
            return TinyPtr<D>{p, 0};
        }
        else if constexpr (sizeof(T) < sizeof(D))
        {
            return TinyPtr<D>{p, exactDiv(offset, exactDiv(sizeof(D), sizeof(T)))};
        }
        else
        {
            return TinyPtr<D>{p, offset * exactDiv(sizeof(T), sizeof(D))};
        }
    }

    __device__ __host__ inline T& operator*() const
    {
        return base[offset];
    }

    __device__ __host__ inline TinyPtr<T> operator+(uint32_t i) const
    {
        return TinyPtr<T>{base, offset + i};
    }

    __device__ __host__ inline T& operator[](uint32_t i) const
    {
        return *(*this + i);
    }

    __device__ __host__ inline operator T*() const
    {
        return base + offset;
    }
};

template <typename OffsetInt = uint32_t>
class Segmenter
{
public:
    HOST_DEVICE_FUNC Segmenter(uint32_t offset = 0)
        : mNextOffset{offset}
    {
    }

    // offset is in bytes
    template <typename T>
    HOST_DEVICE_FUNC OffsetInt newSeg(uint32_t count = 1, uint32_t alignment = alignof(T))
    {
        mMaxAlignment = mha::max<uint32_t>(mMaxAlignment, alignment);
        OffsetInt const offset = roundUp<OffsetInt>(mNextOffset, alignment);
        mNextOffset = offset + sizeof(T) * count;
        return offset;
    }

    HOST_DEVICE_FUNC OffsetInt getEndOffset() const
    {
        return mNextOffset;
    }

    HOST_DEVICE_FUNC uint32_t getMaxAlignment() const
    {
        return mMaxAlignment;
    }

private:
    OffsetInt mNextOffset;
    uint32_t mMaxAlignment = 1;
};

template <typename T, bool addConst>
using AddConst = mha::conditional_t<addConst, T const, T>;

template <bool isConst, typename OffsetInt = uint32_t>
class MemSegmenter
{
public:
    HOST_DEVICE_FUNC MemSegmenter(AddConst<void, isConst>* base, uint32_t offset = 0)
        : mBase{static_cast<AddConst<mha::byte, isConst>*>(base)}
        , mSegmenter{offset}
    {
    }

    // to use TinyPtr, alignment must be sizeof(T)
    template <typename T>
    HOST_DEVICE_FUNC TinyPtr<AddConst<T, isConst>> newSeg(uint32_t count = 1, uint32_t alignment = sizeof(T))
    {
        assert(reinterpret_cast<uintptr_t>(mBase) % alignment == 0);
        OffsetInt const offset = mSegmenter.template newSeg<T>(count, alignment);
        return TinyPtr<AddConst<mha::byte, isConst>>{mBase, offset}.template cast<AddConst<T, isConst>>();
    }

    HOST_DEVICE_FUNC OffsetInt getEndOffset() const
    {
        return mSegmenter.getEndOffset();
    }

    HOST_DEVICE_FUNC uint32_t getMaxAlignment() const
    {
        return mSegmenter.getMaxAlignment();
    }

private:
    AddConst<mha::byte, isConst>* mBase;
    Segmenter<OffsetInt> mSegmenter;
};

// dims in little endian
template <uint32_t nbDims_>
struct DimsLE
{
    static constexpr uint32_t nbDims = nbDims_;

    __device__ __host__ inline uint32_t& operator[](uint32_t i)
    {
        return d[i];
    }

    __device__ __host__ inline uint32_t const& operator[](uint32_t i) const
    {
        return d[i];
    }

    uint32_t d[nbDims];
};

// check if val is in range [lb, ub)
template <typename T>
constexpr bool inRange(T val, T lb, T ub)
{
    return val >= lb && val < ub;
}

// val is an optimized / pre-computed value, ref is the original value
template <typename T>
HOST_DEVICE_FUNC constexpr inline T checkedVal(T val, T ref)
{
    assert(val == ref);
    return val;
}