/***
    Copyright (C) 2023 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuConditionMutex.Linux.cpp
    Date: 2023-8-11
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuConditionMutex.Generic.hpp"
#include "SMTYield.hpp"

#if !defined(_AURUNTIME_GENERICCV) 
#include <Source/Time/Time.hpp>

namespace Aurora::Threading::Primitives
{
    LinuxConditionMutex::LinuxConditionMutex()
    {

    }

    LinuxConditionMutex::~LinuxConditionMutex()
    {
        
    }

    bool LinuxConditionMutex::LockMS(AuUInt64 uTimeout)
    {
        return LockNS(AuMSToNS<AuUInt64>(uTimeout));
    }

    bool LinuxConditionMutex::LockNS(AuUInt64 uTimeout)
    {
        if (TryLockNoSpin())
        {
            return true;
        }
   
        return LockNS(AuTime::SteadyClockNS() + uTimeout);
    }

    bool LinuxConditionMutex::LockAbsMS(AuUInt64 uTimeout)
    {
        return LockAbsNS(AuMSToNS<AuUInt64>(uTimeout));
    }

    bool LinuxConditionMutex::LockAbsNS(AuUInt64 uTimeout)
    {
        struct timespec tspec;

        if (TryLockNoSpin())
        {
            return true;
        }

        if (uTimeout != 0)
        {
            Time::monoabsns2ts(&tspec, uTimeout);
        }

        if (TryLockHeavy())
        {
            return true;
        }

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

        auto state = this->uState_;
        while (!(state == 0 && 
                 AuAtomicCompareExchange<AuUInt32>(&this->uState_, 1, state) == state))
        {
            if (uTimeout != 0)
            {
                if (Time::SteadyClockNS() >= uTimeout)
                {
                    AuAtomicSub(&this->uSleeping_, 1u);
                    return false;
                }

                int ret {};
                do
                {
                    ret = futex_wait(&this->uState_, state, &tspec);
                }
                while (ret == EINTR);
            }
            else
            {
                int ret {};
                bool bStatus {};

                do
                {
                    if ((ret = futex_wait(&this->uState_, state)) == 0)
                    {
                        bStatus = true;
                        break;
                    }

                    if (ret == EAGAIN || errno == EAGAIN)
                    {
                        bStatus = true;
                        break;
                    }
                    
                }
                while (ret == EINTR);

                RUNTIME_ASSERT_SHUTDOWN_SAFE(bStatus, "Mutex wait failed: {}", ret)
            }

            state = this->uState_;
        }

        AuAtomicSub(&this->uSleeping_, 1u);
        return true;
    }

    bool LinuxConditionMutex::TryLock()
    {
        if (gRuntimeConfig.threadingConfig.bPreferLinuxCondMutexSpinTryLock)
        {
            return TryLockHeavy();
        }
        else
        {
            return TryLockNoSpin();
        }
    }

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

    bool LinuxConditionMutex::TryLockHeavy()
    {
        return DoTryIf([=]()
        {
            return TryLockNoSpin();
        });
    }

    void LinuxConditionMutex::Lock()
    {
        if (TryLockHeavy())
        {
            return;
        }

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

        auto state = this->uState_;
        while (!(state == 0 && 
                 AuAtomicCompareExchange<AuUInt32>(&this->uState_, 1, state) == state))
        {
           
            int ret {};
            bool bStatus {};

            do
            {
                if ((ret = futex_wait(&this->uState_, state)) == 0)
                {
                    bStatus = true;
                    break;
                }

                if (ret == EAGAIN || errno == EAGAIN)
                {
                    bStatus = true;
                    break;
                }
                
            }
            while (ret == EINTR);

            RUNTIME_ASSERT_SHUTDOWN_SAFE(bStatus, "Mutex wait failed: {}", ret)

            state = this->uState_;
        }

        AuAtomicSub(&this->uSleeping_, 1u);
    }

    void LinuxConditionMutex::Unlock()
    {
        AuAtomicClearU8Lock(&this->uState_);
        if (AuAtomicLoad(&this->uSleeping_))
        {
            futex_wake(&this->uState_, 1);
        }
    }

    AuUInt LinuxConditionMutex::GetOSHandle()
    {
        return AuMach(&this->uState_);
    }

    AUKN_SYM IConditionMutex *ConditionMutexNew()
    {
        return _new ConditionMutexImpl();
    }

    AUKN_SYM void ConditionMutexRelease(IConditionMutex *mutex)
    {
        AuSafeDelete<ConditionMutexImpl *>(mutex);
    }

    AUROXTL_INTERFACE_SOO_SRC_EX(AURORA_SYMBOL_EXPORT, ConditionMutex, ConditionMutexImpl)
}

#endif