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

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

#if defined(_AURUNTIME_GENERIC_MUTEX)

namespace Aurora::Threading::Primitives
{
    MutexGenericImpl::MutexGenericImpl()
    {
        this->state_ = 0;
    }

    MutexGenericImpl::~MutexGenericImpl()
    {

    }

    bool MutexGenericImpl::HasOSHandle(AuMach &mach)
    {
        return false;
    }

    bool MutexGenericImpl::HasLockImplementation()
    {
        return true;
    }

    bool MutexGenericImpl::TryLock()
    {
        if (ThrdCfg::gPreferUnixPrimitivesNoSpin)
        {
            return this->TryLockNoSpin();
        }
        else
        {
            return this->TryLockHeavy();
        }
    }

    bool MutexGenericImpl::TryLockNoSpin()
    {
        return AuAtomicTestAndSet(&this->state_, 0) == 0;
    }

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

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

    bool MutexGenericImpl::LockNS(AuUInt64 uTimeout)
    {
        AuUInt64 uStart {};
        AuUInt64 uEnd {};
        bool bStatus { true };

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

        if (uTimeout != 0)
        {
            uStart = AuTime::SteadyClockNS();
            uEnd   = uStart + uTimeout;
        }

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

        AuAtomicAdd(&this->dwSleeping_, 1u);

        while (!this->TryLockNoSpin())
        {
            static const AuUInt32 kRef { 1 };

            if (uTimeout != 0)
            {
                if (!InternalLTSWaitOnAddressHighRes((void *)&this->state_, &kRef, 4, uEnd))
                {
                    bStatus = false;
                    break;
                }
            }
            else
            {
                (void)InternalLTSWaitOnAddressHighRes((void *)&this->state_, &kRef, 4, uEnd);
            }
        }

        AuAtomicSub(&this->dwSleeping_, 1u);
        return bStatus;
    }

    bool MutexGenericImpl::LockAbsNS(AuUInt64 uEndTime)
    {
        bool bStatus { true };

        if (ThrdCfg::gPreferUnixPrimitivesNoSpin)
        {
            if (this->TryLockNoSpin())
            {
                return true;
            }
        }
        else
        {
            if (this->TryLockHeavy())
            {
                return true;
            }
        }

        AuAtomicAdd(&this->dwSleeping_, 1u);

        while (!this->TryLockNoSpin())
        {
            static const AuUInt32 kRef { 1 };

            if (uEndTime != 0)
            {
                if (!InternalLTSWaitOnAddressHighRes((void *)&this->state_, &kRef, 4, uEndTime))
                {
                    bStatus = false;
                    break;
                }
            }
            else
            {
                (void)InternalLTSWaitOnAddressHighRes((void *)&this->state_, &kRef, 4, uEndTime);
            }
        }

        AuAtomicSub(&this->dwSleeping_, 1u);
        return bStatus;
    }

    void MutexGenericImpl::SlowLock()
    {
        (void)this->LockAbsNS(0);
    }

    void MutexGenericImpl::Unlock()
    {
        AuAtomicClearU8Lock(&this->state_);

        if (AuAtomicLoad(&this->dwSleeping_))
        {
            InternalLTSWakeOne((void *)&this->state_);
        }
    }

    AUKN_SYM IHyperWaitable *MutexNew()
    {
        return _new MutexGenericImpl();
    }

    AUKN_SYM void MutexRelease(IHyperWaitable *pMutex)
    {
        AuSafeDelete<MutexGenericImpl *>(pMutex);
    }

    AUROXTL_INTERFACE_SOO_SRC_EX(AURORA_SYMBOL_EXPORT, Mutex, MutexGenericImpl)
    
}
#endif