/***
    Copyright (C) 2021-2024 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuSemaphore.NT.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuSemaphore.Generic.hpp"
#include "SMTYield.hpp"
#include "../AuWakeInternal.hpp"

#if !defined(_AURUNTIME_GENERIC_SEMAPHORE)

namespace Aurora::Threading::Primitives
{
    SemaphoreImpl::SemaphoreImpl(AuUInt16 uIntialValue)
    {
        this->dwState_ = uIntialValue;
    }
    
    SemaphoreImpl::~SemaphoreImpl()
    {
    }

    bool SemaphoreImpl::HasOSHandle(AuMach &mach)
    {
        return false;
    }
    
    bool SemaphoreImpl::HasLockImplementation()
    {
        return true;
    }

    bool SemaphoreImpl::TryLockNoSpin()
    {
        AuUInt32 uOld {};
        
        while ((uOld = this->dwState_))
        {
            if (AuAtomicCompareExchange(&this->dwState_, uOld - 1, uOld) == uOld)
            {
                return true;
            }
        }

        return false;
    }

    bool SemaphoreImpl::TryLockHeavy()
    {
        return DoTryIfAlderLake([=]()
        {
            return this->TryLockNoSpin();
        }, &this->dwState_);
    }

    bool SemaphoreImpl::TryLock()
    {
        if (ThrdCfg::gPreferNtSemaphoreSpinTryLock)
        {
            return this->TryLockHeavy();
        }
        else
        {
            return this->TryLockNoSpin();
        }
    }
    
    AuUInt32 *SemaphoreImpl::GetSleepCounter()
    {
        return (AuUInt32 *)&this->var;
    }

    bool SemaphoreImpl::LockMS(AuUInt64 uTimeout)
    {
        return this->LockNS(AuMSToNS<AuUInt64>(uTimeout));
    }

    bool SemaphoreImpl::LockNS(AuUInt64 uTimeout)
    {
        AuUInt64 uStart {};
        AuUInt64 uEnd {};

        if (this->TryLockNoSpin())
        {
            return true;
        }

        if (uTimeout)
        {
            uStart = AuTime::SteadyClockNS();
            uEnd   = uStart + uTimeout;
        }

        if (this->TryLockHeavy())
        {
            return true;
        }

        if (gUseNativeWaitSemapahore)
        {
            auto pCounter = this->GetSleepCounter();

            while (!this->TryLockNoSpin())
            {
                static const AuUInt32 kExpect { 0 };

                AuAtomicAdd(pCounter, 1u);
                bool bStatus = InternalLTSWaitOnAddressHighRes(&this->dwState_, &kExpect, sizeof(kExpect), uEnd);
                AuAtomicSub(pCounter, 1u);

                if (!bStatus)
                {
                    return false;
                }
            }

            return true;
        }
        else
        {
            this->mutex.Lock();

            while (!this->TryLockNoSpin())
            {
                if (uTimeout != 0)
                {
                    uStart = Time::SteadyClockNS();
                    if (uStart >= uEnd)
                    {
                        this->mutex.Unlock();
                        return false;
                    }

                    var.WaitForSignalNsEx(&this->mutex, uEnd - uStart, false);
                }
                else
                {
                    var.WaitForSignalNsEx(&this->mutex, 0, false);
                }
            }

            this->mutex.Unlock();

            return true;
        }
    }

    bool SemaphoreImpl::LockAbsNS(AuUInt64 qwTimeoutAbs)
    {
        if (this->TryLockHeavy())
        {
            return true;
        }

        if (gUseNativeWaitSemapahore)
        {
            AuUInt32 uYieldCounter {};
            auto pCounter = this->GetSleepCounter();

            while (!this->TryLockNoSpin())
            {
                static const AuUInt32 kExpect { 0 };

                AuAtomicAdd(pCounter, 1u);
                bool bStatus = InternalLTSWaitOnAddressHighRes(&this->dwState_, &kExpect, sizeof(kExpect), qwTimeoutAbs);
                AuAtomicSub(pCounter, 1u);

                if (!bStatus)
                {
                    return false;
                }
            }

            return true;
        }
        else
        {
            this->mutex.Lock();

            while (!this->TryLockNoSpin())
            {
                if (qwTimeoutAbs != 0)
                {
                    auto uStart = Time::SteadyClockNS();
                    if (uStart >= qwTimeoutAbs)
                    {
                        this->mutex.Unlock();
                        return false;
                    }

                    var.WaitForSignalNsEx(&this->mutex, qwTimeoutAbs - uStart, false);
                }
                else
                {
                    var.WaitForSignalNsEx(&this->mutex, 0, false);
                }
            }

            this->mutex.Unlock();

            return true;
        }
    }
    
    void SemaphoreImpl::Lock()
    {
        auto status = LockNS(0);
        SysAssert(status, "Couldn't lock semaphore");
    }
    
    void SemaphoreImpl::Unlock(AuUInt16 uCount)
    {
        if (uCount == 0)
        {
            return;
        }

        AuAtomicAdd<AuUInt32>(&this->dwState_, uCount);

        if (gUseNativeWaitSemapahore)
        {
            if (auto dwSleeping = AuAtomicLoad(this->GetSleepCounter()))
            {
                if (uCount == 1)
                {
                    InternalLTSWakeOne((void *)&this->dwState_);
                }
                else
                {
                    InternalLTSWakeCount((void *)&this->dwState_, AuMin<AuUInt32>(uCount, dwSleeping));
                }
            }
        }
        else
        {
             // do not [re]move this lock fence
            {
                this->mutex.Lock();
                this->mutex.Unlock();
            }
            
            if (uCount == 1)
            {
                this->var.Signal();
            }
            else
            {
                this->var.BroadcastN(uCount);
            }
        }
    }
    
    void SemaphoreImpl::Unlock()
    {
        return Unlock(1);
    }
    
    AUKN_SYM ISemaphore *SemaphoreNew(AuUInt16 uIntialValue)
    {
        return _new SemaphoreImpl(uIntialValue);
    }

    AUKN_SYM void SemaphoreRelease(ISemaphore *pSemaphore)
    {
        AuSafeDelete<SemaphoreImpl *>(pSemaphore);
    }

    AUROXTL_INTERFACE_SOO_SRC_EX(AURORA_SYMBOL_EXPORT, Semaphore, SemaphoreImpl)
}
#endif