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

    File: AuMutex.Win32.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuMutex.Generic.hpp"

#if !defined(_AURUNTIME_GENERICMUTEX)
#include "AuMutex.NT.hpp"

namespace Aurora::Threading::Primitives
{
    static BOOL (_stdcall *WaitOnAddress_f)(
        volatile VOID *Address,
        PVOID         CompareAddress,
        SIZE_T        AddressSize,
        DWORD         dwMilliseconds
    ) = 
    #if defined(AURORA_PLATFORM_WIN32)
        decltype(WaitOnAddress_f)(GetProcAddress(LoadLibraryA("API-MS-Win-Core-Synch-l1-2-0.dll"), "WaitOnAddress"));
    #else
        WaitOnAddress;
    #endif

    static void(_stdcall *WakeByAddressSingle_f)(
        PVOID Address
    ) =
    #if defined(AURORA_PLATFORM_WIN32)
        decltype(WakeByAddressSingle_f)(GetProcAddress(LoadLibraryA("API-MS-Win-Core-Synch-l1-2-0.dll"), "WakeByAddressSingle"));
    #else
        WakeByAddressSingle;
    #endif

    Mutex::Mutex()
    {
        if (!WaitOnAddress_f)
        {
            ::InitializeSRWLock(&this->atomicHolder_);
            ::InitializeConditionVariable(&this->wakeup_);
        }
        this->state_ = 0;
    }

    Mutex::~Mutex()
    {

    }

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

    bool Mutex::TryLock()
    {
        return ::_interlockedbittestandset(&this->state_, 0) == 0;
    }

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

    void Mutex::Lock()
    {
        auto status = Lock(0);
        SysAssert(status, "Couldn't lock Mutex object");
    }

    bool Mutex::Lock(AuUInt64 timeout)
    {
        bool returnValue = false;

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

        AuInt64 uStartTime = Time::SteadyClockMS();
        AuInt64 uEndTime   = uStartTime + timeout;

        if (WaitOnAddress_f)
        {
            auto state = this->state_;
            while (::_interlockedbittestandset(&this->state_, 0) != 0)
            {
                AuUInt32 uTimeoutMS = INFINITE;

                if (timeout != 0)
                {
                    uStartTime = Time::SteadyClockMS();
                    if (uStartTime >= uEndTime)
                    {
                        return false;
                    }

                    uTimeoutMS = uEndTime - uStartTime;
                }

                if (!WaitOnAddress_f(&this->state_, &state, sizeof(this->state_), uTimeoutMS))
                {
                    SysAssertExp(GetLastError() == ERROR_TIMEOUT);
                    return false;
                }

                state = this->state_;
            }

            return true;
        }
        else
        {
            ::AcquireSRWLockShared(&this->atomicHolder_);

            BOOL status = false;
            while (!this->TryLock())
            {
                AuUInt32 uTimeoutMS = INFINITE;

                if (timeout != 0)
                {
                    uStartTime = Time::SteadyClockMS();
                    if (uStartTime >= uEndTime)
                    {
                        goto exitWin32;
                    }

                    uTimeoutMS = uEndTime - uStartTime;
                }

                status = ::SleepConditionVariableSRW(&this->wakeup_, &this->atomicHolder_, uTimeoutMS, CONDITION_VARIABLE_LOCKMODE_SHARED);
                if (!status)
                {
                    SysAssertExp(GetLastError() == ERROR_TIMEOUT);
                    goto exitWin32;
                }
            }

            returnValue = true;

        exitWin32:
            ::ReleaseSRWLockShared(&this->atomicHolder_);
            return returnValue;
        }
    }

    void Mutex::Unlock()
    {
        if (!WaitOnAddress_f)
        {
            ::AcquireSRWLockExclusive(&this->atomicHolder_);
            this->state_ = 0;
            ::ReleaseSRWLockExclusive(&this->atomicHolder_);
            ::WakeAllConditionVariable(&this->wakeup_);
        }
        else
        {
            this->state_ = 0;
            WakeByAddressSingle_f((void *)&this->state_);
        }
    }
    
    AUKN_SYM IWaitable *MutexNew()
    {
        return _new Mutex();
    }

    AUKN_SYM void MutexRelease(IWaitable *pMutex)
    {
        AuSafeDelete<Mutex *>(pMutex);
    }
}

#endif