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

    File: LSTimer.NT.cpp
    Date: 2021-10-1
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "LSTimer.hpp"
#include <Source/Time/Time.hpp>

namespace Aurora::IO::Loop
{
    static AuUInt32 gHighResTimers {};

    LSTimer::LSTimer(AuUInt32 reschedStepMsOrZero, AuUInt32 maxIterationsOrZero, bool bSingleshot, HANDLE handle, bool bHighRes) :
        LSHandle(AuReinterpretCast<AuUInt>(handle)),
        reschedStepNsOrZero_(AuMSToNS<AuUInt64>(reschedStepMsOrZero)),
        bSingleshot(bSingleshot),
        maxIterationsOrZero_(maxIterationsOrZero),
        bHighRes_(bHighRes)
    {
        this->targetTime_ = AuTime::ConvertTimestamp(AuTime::CurrentClockMS());

        if (this->bHighRes_)
        {
            if (AuAtomicAdd(&gHighResTimers, 1u) == 1)
            {
                Win32DropSchedulerResolutionForced();
            }
        }
    }

    LSTimer::~LSTimer()
    {
        auto handle = AuReinterpretCast<HANDLE>(this->handle);
        AuWin32CloseHandle(handle);
        this->handle = kInvalidHandle;

        if (this->bHighRes_)
        {
            if (AuAtomicSub(&gHighResTimers, 1u) == 0)
            {
                Win32DropSchedulerResolutionForcedUndo();
            }
        }
    }

    void LSTimer::UpdateTimeWall(AuUInt64 absTimeMs)
    {
        UpdateTimeInternalNTWall(AuTime::ConvertTimestamp(absTimeMs));
    }

    void LSTimer::UpdateTimeWallNs(AuUInt64 absTimeNs)
    {
        UpdateTimeInternalNTWall(AuTime::ConvertTimestampNs(absTimeNs));
    }

    void LSTimer::UpdateTimeSteady(AuUInt64 absTimeMs)
    {
        UpdateTimeSteadyNs(AuMSToNS<AuUInt64>(absTimeMs));
    }

    void LSTimer::UpdateTimeSteadyNs(AuUInt64 absTimeNs)
    {
        UpdateTimeWallNs(absTimeNs - AuTime::SteadyClockNS() + AuTime::CurrentClockNS());
    }

    void LSTimer::UpdateTimeInternalNTWall(AuUInt64 absTimeNs)
    {
        LARGE_INTEGER i;
        this->targetTime_ = absTimeNs;
        i.QuadPart = absTimeNs;
        SysAssert(::SetWaitableTimer(AuReinterpretCast<HANDLE>(this->handle), &i, 0, nullptr, nullptr, false));
    }

    void LSTimer::UpdateTickRateIfAny(AuUInt32 reschedStepMsOrZero, AuUInt32 maxIterationsOrZero)
    {
        this->reschedStepNsOrZero_ = AuMSToNS<AuUInt64>(reschedStepMsOrZero);
        this->maxIterationsOrZero_ = maxIterationsOrZero;
        this->count_ = 0;
        UpdateTimeInternalNTWall(this->targetTime_);
    }

    void LSTimer::UpdateTickRateIfAnyNs(AuUInt64 reschedStepNsOrZero, AuUInt32 maxIterationsOrZero)
    {
        this->reschedStepNsOrZero_ = reschedStepNsOrZero;
        this->maxIterationsOrZero_ = maxIterationsOrZero;
        this->count_ = 0;
        UpdateTimeInternalNTWall(this->targetTime_);
    }
    
    bool LSTimer::OnTrigger(AuUInt handle)
    {
        if (!this->reschedStepNsOrZero_)
        {
            return true;
        }

        auto uCurrentTime = AuTime::ConvertTimestampNs(AuTime::CurrentClockNS());
        auto uNextTick = this->targetTime_ + (AuUInt64(this->reschedStepNsOrZero_) / 100ULL);

        if (this->targetTime_ > uCurrentTime || 
            uCurrentTime > uNextTick)
        {
            this->targetTime_ = uCurrentTime;
            uNextTick = this->targetTime_ + (AuUInt64(this->reschedStepNsOrZero_) / 100ULL);
        }

        if (!this->maxIterationsOrZero_)
        {
            this->UpdateTimeInternalNTWall(uNextTick);
            return true;
        }

        if (AuAtomicAdd<AuUInt32>(&this->count_, 1) <= this->maxIterationsOrZero_)
        {
            this->UpdateTimeInternalNTWall(uNextTick);
            return true;
        }
        else
        {
            Stop();
            return false;
        }
    }

    void LSTimer::Stop()
    {
        bool bSuccess = ::CancelWaitableTimer(AuReinterpretCast<HANDLE>(handle));
        SysAssertDbg(bSuccess);
        LARGE_INTEGER i;
        i.QuadPart = AuNumericLimits<AuInt64>::max();
        SysAssert(::SetWaitableTimer(AuReinterpretCast<HANDLE>(this->handle), &i, 0, nullptr, nullptr, false));
    }

    bool LSTimer::IsSignaled()
    {
        return LSHandle::IsSignaled();
    }

    bool LSTimer::WaitOn(AuUInt32 timeout)
    {
        return LSHandle::WaitOn(timeout);
    }

    ELoopSource LSTimer::GetType()
    {
        return ELoopSource::eSourceTimer;
    }

    AuSPtr<ITimer> NewLSTimerOS(AuUInt64 absStartTimeMs, AuUInt32 reschedStepMsOrZero, AuUInt32 maxIterationsOrZero, bool bSingleshot, bool bIsStartTimeSteady)
    {
        auto handle = CreateWaitableTimerW(nullptr, !bSingleshot, nullptr);
        if (!handle)
        {
            SysPushErrorIO();
            return {};
        }

        auto object = AuMakeShared<LSTimer>(reschedStepMsOrZero, maxIterationsOrZero, bSingleshot, handle, false);
        if (!object)
        {
            SysPushErrorMem();
            AuWin32CloseHandle(handle);
            return {};
        }

        if (absStartTimeMs)
        {
            if (bIsStartTimeSteady)
            {
                object->UpdateTimeSteady(absStartTimeMs);
            }
            else
            {
                object->UpdateTimeWall(absStartTimeMs);
            }
        }

        return object;
    }

    AuSPtr<ITimer> NewLSTimerOSHiRes(AuUInt64 absStartTimeMs, AuUInt32 reschedStepMsOrZero, AuUInt32 maxIterationsOrZero, bool bSingleshot, bool bIsStartTimeSteady)
    {
        if (!AuSWInfo::IsWindows10MilestoneRS4OrGreater())
        {
            return {};
        }

        if (!pCreateWaitableTimerExW)
        {
            return {};
        }

        auto handle = pCreateWaitableTimerExW(nullptr, nullptr, (bSingleshot ? 0 : 1) | CREATE_WAITABLE_TIMER_HIGH_RESOLUTION, TIMER_ALL_ACCESS);
        if (!handle)
        {
            SysPushErrorIO();
            return {};
        }

        auto object = AuMakeShared<LSTimer>(reschedStepMsOrZero, maxIterationsOrZero, bSingleshot, handle, true);
        if (!object)
        {
            SysPushErrorMem();
            AuWin32CloseHandle(handle);
            return {};
        }

        if (absStartTimeMs)
        {
            if (bIsStartTimeSteady)
            {
                object->UpdateTimeSteady(absStartTimeMs);
            }
            else
            {
                object->UpdateTimeWall(absStartTimeMs);
            }
        }

        return object;
    }
}