/***
    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::Loop
{
    struct LSTimer : ITimer, LSHandle
    {
        LSTimer(AuUInt32 reschedStepMsOrZero, AuUInt32 maxIterationsOrZero, bool bSingleshot, HANDLE handle);
        ~LSTimer();

        virtual void UpdateTime(AuUInt64 absTimeMs) override;
        virtual void UpdateTimeNs(AuUInt64 absTimeNs) override;
        virtual void UpdateTickRateIfAny(AuUInt32 reschedStepMsOrZero, AuUInt32 maxIterationsOrZero) override;
        virtual void UpdateTickRateIfAnyNs(AuUInt64 reschedStepNsOrZero, AuUInt32 maxIterationsOrZero) override;
        virtual void Stop() override;

        virtual bool OnTrigger(AuUInt handle) override;

        virtual bool IsSignaled() override;
        virtual bool WaitOn(AuUInt32 timeout) override;
        virtual ELoopSource GetType() override;

        void UpdateTimeInternal(AuUInt64 absTimeNs);

    private:
        AuUInt64 reschedStepNsOrZero_ {0};
        AuUInt32 maxIterationsOrZero_ {0};
        AuUInt64 targetTime_ {0};
        AuUInt32 count_ {0};
        bool bSingleshot {};
    };

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

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

    void LSTimer::UpdateTime(AuUInt64 absTimeMs)
    {
        this->targetTime_ = AuTime::ConvertTimestamp(absTimeMs);
        UpdateTimeInternal(this->targetTime_);
    }

    void LSTimer::UpdateTimeNs(AuUInt64 absTimeNs)
    {
        this->targetTime_ = AuTime::ConvertTimestampNs(absTimeNs);
        UpdateTimeInternal(this->targetTime_);
    }

    void LSTimer::UpdateTimeInternal(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;
    }

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

        if (!this->maxIterationsOrZero_)
        {
            this->UpdateTimeInternal(this->targetTime_ + (AuUInt64(this->reschedStepNsOrZero_) / 100ULL));
            return true;
        }

        bool ok = AuAtomicAdd<AuUInt32>(&this->count_, 1) <= this->maxIterationsOrZero_;
        if (ok)
        {
            this->UpdateTimeInternal(this->targetTime_ + (AuUInt64(this->reschedStepNsOrZero_) / 100ULL));
            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;
    }

    AUKN_SYM AuSPtr<ITimer> NewLSTimer(AuUInt64 absStartTimeMs, AuUInt32 reschedStepMsOrZero, AuUInt32 maxIterationsOrZero, bool bSingleshot)
    {
        // https://docs.microsoft.com/en-us/windows/win32/api/threadpoolapiset/nf-threadpoolapiset-setthreadpoolwait
        // TODO: Is that any better with an event?

        auto handle = CreateWaitableTimerW(nullptr, !bSingleshot, nullptr);
        if (!handle)
        {
            SysPushErrorIO();
            return {};
        }

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

        if (absStartTimeMs)
        {
            object->UpdateTime(absStartTimeMs);
        }

        return object;
    }
}