/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: Heap.hpp
    Date: 2021-6-9
    Author: Reece
***/
#pragma once

namespace Aurora::Memory
{
    struct ProxyHeap;
    static const AuUInt8 kHeapSize  = 128;
    static const AuUInt8 kHeap2Size = 255;

    template <class T>
    struct CppHeapWrapper;

    /**
     * Note: The following public aliases for heap or global process heap based allocations exist:
     * 
     *   AuHUPOf_t<T> AuNewClassArrayUnique([pHeap, ]uElements, ...)
     *   AuSPtr<T>    AuNewClassArray([pHeap, ]uElements, ...)
     *   AuHUPOf_t<T> AuNewClassUnique([pHeap, ] ...)
     *   AuSPtr<T>    AuNewClass([pHeap, ] ...)
     *   AuHUPOf_t<T> AuNullHeapPointer<T>()
     */

    struct Heap
    {
        virtual AuSPtr<Heap> AllocateDivision(AuUInt32 heap, AuUInt32 alignment = 32) = 0;
        virtual Types::size_t GetChunkSize(const void *pHead) = 0;
        virtual HeapStats &GetStats() = 0;
        virtual void WalkHeap(bool(*fCallback)(void *, void *), void *pSecondArg) = 0;

        /// Potentially slower, zero allocate
        template<typename T = void *>
        T ZAlloc(Types::size_t uLength);

        /// POD zero allocation
        template<typename T = void *>
        T ZAlloc(Types::size_t uLength, Types::size_t uAlignment);

        /// POD zero allocation
        template<typename T>
        T *ZAlloc();

        /// POD array, zero allocation
        template<typename T>
        T *NewArray(Types::size_t uLength);

        /// POD array, zero allocation
        template<typename T>
        T *NewArray(Types::size_t uLength, Types::size_t uAlignment);

        /// Fast, POD, non-zeroing allocation
        template<typename T = void *>
        T FAlloc(Types::size_t uLength);

        /// Fast, POD, non-zeroing allocation
        template<typename T = void *>
        T FAlloc(Types::size_t uLength, Types::size_t uAlignment);

        /// Fast, POD, non-zeroing allocation
        template<typename T>
        T *FAlloc();

        // Reallocs

        /// POD, zero-based expansion or reallocation
        template<typename T>
        T ZRealloc(T pHead, Types::size_t uLength);

        /// POD, zero-based expansion or reallocation
        template<typename T>
        T ZRealloc(T pHead, Types::size_t uLength, Types::size_t uAlignment);

        /// POD, expansion or reallocation
        template<typename T>
        T FRealloc(T pHead, Types::size_t uLength);

        /// POD, expansion or reallocation
        template<typename T>
        T FRealloc(T pHead, Types::size_t uLength, Types::size_t uAlignment);

        /// Free
        template<typename T>
        void Free(T pHead);

    protected:

        template <typename T>
        static void DeleteThat(T *pThat);

        template <typename T>
        static void DeleteThatArray(T *pThat);
        
        template <typename T, typename Z>
        static void DeleteThatCastedOnce(T *pThat);

        template <typename T>
        static void RetardedSpecWrittenByRetards(T *pThat);

    public:

        template <class T, class ...Args>
        AuSPtr<T> NewClass(Args &&...args);

            // note: callers can use AuHUPOf_t<Z> pUniquePointer = AuNullHeapPointer<Z>()

        template <class T, class Z = T, class ...Args>
        AuUPtr<Z, decltype(&Heap::DeleteThat<Z>)> NewClassUnique(Args &&...args);

        template <class T, class ...Args>
        AuSPtr<T> NewClassArray(AuUInt uElements, Args &&... fillCtr);

        template <class T, class ...Args>
        AuSPtr<T> NewClassArray2(AuUInt uElements, AuUInt uAlignment, Args &&... fillCtr);

            // note: callers can use AuHUPOf_t<T> pUniquePointer = AuNullHeapPointer<T>()

        template <class T, class ...Args>
        AuUPtr<T, decltype(&Heap::DeleteThat<T>)> NewClassArrayUnique(AuUInt uElements, Args &&... fillCtr);

        template <class T, class ...Args>
        AuUPtr<T, decltype(&Heap::DeleteThat<T>)> NewClassArray2Unique(AuUInt uElements, AuUInt uAlignment, Args &&... fillCtr);

        template <class T>
        cstatic AuUPtr<T, decltype(&Heap::DeleteThat<T>)> NullUniquePointer();

        template <class Z, class T>
        cstatic AuUPtr<Z, decltype(&Heap::DeleteThat<Z>)> CastPointer(AuUPtr<T, decltype(&Heap::DeleteThat<T>)> &&pInPointer);

        template <typename T>
        using HUPOf_t = AuUPtr<T, decltype(&Heap::DeleteThat<T>)>;

    protected:
        friend struct ProxyHeap;
        friend struct HeapAccessor;

        virtual AuSPtr<Heap> GetSelfReference() = 0; // may return empty/default. not all heaps are sharable.
        virtual Heap *GetSelfReferenceRaw() = 0;

        virtual AU_ALLOC void *_ZAlloc(Types::size_t uLength) = 0;
        virtual AU_ALLOC void *_ZAlloc(Types::size_t uLength, Types::size_t uAlignment) = 0;
        virtual AU_ALLOC void *_FAlloc(Types::size_t uLength) = 0;
        virtual AU_ALLOC void *_FAlloc(Types::size_t uLength, Types::size_t uAlignment) = 0;
        virtual AU_ALLOC void *_ZRealloc(void *pBase, Types::size_t uLength, Types::size_t uAlign) = 0;
        virtual AU_ALLOC void *_ZRealloc(void *pBase, Types::size_t uLength) = 0;
        virtual AU_ALLOC void *_FRealloc(void *pBase, Types::size_t uLength, Types::size_t uAlign) = 0;
        virtual AU_ALLOC void *_FRealloc(void *pBase, Types::size_t uLength) = 0;
        virtual void           _Free(void* pBase) = 0;
    };

    struct HeapAccessor
    {
        cstatic AuSPtr<Heap> GetSelfReference(Heap *pHeap)
        {
            return pHeap->GetSelfReference();
        }

        cstatic Heap *GetSelfReferenceRaw(Heap *pHeap)
        {
            return pHeap->GetSelfReferenceRaw();
        }
    };

    /**
     * Returns a heap interface backed by the default allocator
     */
    AUKN_SHARED_API(DefaultDiscontiguousHeap, Heap);

    inline Heap *GetDefaultDiscontiguousHeap()
    {
        return DefaultDiscontiguousHeapNew();
    }

    inline AuSPtr<Heap> GetDefaultDiscontiguousHeapShared()
    {
        // Might not allocate the control block under some STLs, unlike DefaultDiscontiguousHeapSharedShared() which will generally always allocate a control block under most STLs
        return AuUnsafeRaiiToShared(GetDefaultDiscontiguousHeap());
    }

    /**
     * Allocates uLength amount of contiguous virtual memory
     * @return a heap backed by uLength bytes of virtual memory
     * @warning the SOO variant cannot guarantee release-on-last-free and will panic if uLength cannot be allocated. Use AllocHeap[Shared/Unique/New](uLength) instead.
     */
    AUKN_SHARED_SOO2_NCM(AllocHeap, Heap, kHeapSize, ((AuUInt, uLength)), AuUInt uLength);

    /**
     * @warning the SOO variant cannot guarantee release-on-last-free and will panic if an invalid memory handle is provided.
     */
    AUKN_SHARED_SOO2_NCM(RequestHeapOfRegion, Heap, kHeapSize, ((const MemoryViewWrite &, memory)), const MemoryViewWrite &memory);

    /**
     * @warning the SOO variant cannot guarantee release-on-last-free and will panic if an invalid memory handle is provided.
     */
    AUKN_SHARED_SOO2_NCM(RequestHeapOfSharedRegion, Heap, kHeapSize, ((const AuSPtr<MemoryViewWrite> &, memory)), const AuSPtr<MemoryViewWrite> &pMemory);

    /**
     * Proxies an existing heap with encapsulated statistics.
     * This is intended for debugging purposes when accurate heap stats of a heap-subset are desired.
     * @warning this heap cannot guarantee release-on-last-free
     */
    AUKN_SHARED_SOO2_NCM(HeapProxy, Heap, kHeap2Size, ((const AuSPtr<Heap> &, pHead)), const AuSPtr<Heap> &pHead);

    /**
     * Proxies an existing heap with encapsulated statistics and leak detector
     * This is intended for debugging purposes when accurate heap stats of a heap-subset are desired.
     * @warning this heap cannot guarantee release-on-last-free
    */
    AUKN_SHARED_SOO2_NCM(HeapProxyEx, Heap, kHeap2Size, ((const AuSPtr<Heap> &,pHead), (LeakFinderAlloc_f, pfAlloc), (LeakFinderFree_f, pfFree)), const AuSPtr<Heap> &pHead, LeakFinderAlloc_f pfAlloc, LeakFinderFree_f pfFree);
}