#pragma once

#include "CoreTypes.h"
#include "Memory/Memory.h"
#include "Memory/AllocatorInterface.h"

NAMESPACE_REDCRAFT_BEGIN
NAMESPACE_MODULE_BEGIN(Redcraft)
NAMESPACE_MODULE_BEGIN(Utility)

/** This is heap allocator that calls Memory::Malloc() directly for memory allocation. */
struct FHeapAllocator : public FAllocatorInterface
{
	template <CObject T>
	struct ForElementType : public FAllocatorInterface::ForElementType<T>
	{
		NODISCARD FORCEINLINE T* Allocate(size_t InNum)
		{
			return InNum != 0 ? static_cast<T*>(Memory::Malloc(Memory::QuantizeSize(InNum * sizeof(T)), alignof(T))) : nullptr;
		}

		FORCEINLINE void Deallocate(T* InPtr)
		{
			Memory::Free(InPtr);
		}

		NODISCARD FORCEINLINE constexpr size_t CalculateSlackGrow(size_t Num, size_t NumAllocated) const
		{
			const size_t FirstGrow    = 4;
			const size_t ConstantGrow = 16;

			size_t Result;

			check(Num > NumAllocated);

			Result = (NumAllocated != 0) ? (Num + 3 * Num / 8 + ConstantGrow) : (Num > FirstGrow ? Num : FirstGrow);

			Result = Memory::QuantizeSize(Result * sizeof(T), alignof(T)) / sizeof(T);

			return Result;
		}

		NODISCARD FORCEINLINE constexpr size_t CalculateSlackShrink(size_t Num, size_t NumAllocated) const
		{
			size_t Result;

			check(Num < NumAllocated);

			const bool bTooManySlackBytes    = (NumAllocated - Num) * sizeof(T) >= 16 * 1024;
			const bool bTooManySlackElements = 3 * Num < 2 * NumAllocated;

			const bool bNeedToShrink = (bTooManySlackBytes || bTooManySlackElements) && (NumAllocated - Num > 64 || Num == 0);

			if (bNeedToShrink)
			{
				Result = Num != 0 ? Memory::QuantizeSize(Num * sizeof(T), alignof(T)) / sizeof(T) : 0;
			}
			else
			{
				Result = NumAllocated;
			}

			return Result;
		}

		NODISCARD FORCEINLINE constexpr size_t CalculateSlackReserve(size_t Num) const
		{
			return Num != 0 ? Memory::QuantizeSize(Num * sizeof(T), alignof(T)) / sizeof(T) : 0;
		}

	};
};

NAMESPACE_MODULE_END(Utility)
NAMESPACE_MODULE_END(Redcraft)
NAMESPACE_REDCRAFT_END