// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"

class FZenaphore;

struct FZenaphoreWaiterNode
{
    FZenaphoreWaiterNode* Next = nullptr;
    bool bTriggered            = false;
};

class FZenaphoreWaiter
{
public:
    FZenaphoreWaiter(FZenaphore& Outer, const TCHAR* WaitCpuScopeName)
        : Outer(Outer)
    {
    }

    ~FZenaphoreWaiter();

    void Wait();

private:
    friend class FZenaphore;

    void WaitInternal();

    FZenaphore& Outer;
    FZenaphoreWaiterNode WaiterNode;
    int32 SpinCount = 0;
};

class FZenaphore
{
public:
    FZenaphore();
    ~FZenaphore();
    void NotifyOne();
    void NotifyAll();

private:
    friend class FZenaphoreWaiter;

    void NotifyInternal(FZenaphoreWaiterNode* Waiter);

    FEvent* Event;
    FCriticalSection Mutex;
    TAtomic<FZenaphoreWaiterNode*> HeadWaiter{nullptr};
};