/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: ThroughputCalculator.hpp
    Date: 2022-12-06
    Author: Reece
***/
#pragma once

namespace Aurora::Utility
{      
    struct ThroughputCalculator
    {
        // call me arbitrarily
        double inline OnUpdate(AuUInt uUnit)
        {
            AU_LOCK_GUARD(this->lock);

            OnTick(uUnit);
            return this->dCurFreq;
        }
        

        // then call me arbitrarily:
        double inline GetEstimatedHertz()
        {
            AU_LOCK_GUARD(this->lock);

            auto uNow = Aurora::Time::SteadyClockNS();
            auto uDelta = uNow - this->uLast;
            
            // we cannot do anything on frame zero
            if (!this->dCurFreq)
            {
                return 0;
            }

            return this->dCurFreq;
        }

        AuUInt inline GetTotalStats()
        {
            return this->uTotalLifetime;
        }


        AuInt64 inline GetLastFrameTimeWall()
        {
            return this->uLastWall;
        }
        
    private:

        void inline OnTick(AuUInt64 uUnit)
        {
            struct EntryTable
            {
                AuUInt32 uBits {};
                AuUInt32 uTimeDelta {};
            };

            auto uNow = Aurora::Time::SteadyClockNS();
            auto uDelta = uNow - this->uLast;
            
            AuMemmove(uVecTable + 1, uVecTable, sizeof(uVecTable) - sizeof(*uVecTable));

            auto pTable = ((EntryTable *)uVecTable);
            bool bFirst = !this->uLast;
            this->uLast = uNow;
            if (bFirst)
            {
                return;
            }

            this->uLastWall = Aurora::Time::CurrentClockMS();
           
            static const auto kOneSecond = AuMSToNS<AuUInt64>(AuSToMS<AuUInt64>(1));


            pTable[0].uBits = (AuUInt32)uUnit;
            pTable[0].uTimeDelta = (AuUInt32)(uDelta / 1000ull);
            if (!pTable[0].uTimeDelta)
            {
                pTable[0].uTimeDelta = 1;
            }
            if (uVecSize < 10)
            {
                uVecSize++;
            }

            AuLogDbg("Added: {} {}", pTable[0].uBits, pTable[0].uTimeDelta * 1000ull);

            double dTotal {};
            double dTotalBits {};
            double dTotalTime {};
            double dSamples {};

            for (AU_ITR_N(i, uVecSize))
            {
                if (!pTable[i].uTimeDelta)
                {
                    pTable[i].uTimeDelta = 1;
                }

                double dDeltaSeconds = ((double)((AuUInt64)pTable[i].uTimeDelta * 1000ull) / (double)kOneSecond);

                dTotalBits += pTable[i].uBits;
                dTotalTime += dDeltaSeconds;
                
                dTotal += (double)pTable[i].uBits / dDeltaSeconds;
                
                dSamples++;
            }

            AuLogDbg("{}/{} ({})", dTotal, dSamples, uVecSize);
            this->dCurFreq = dTotal / dSamples;

            double a = dTotalBits / dTotalTime;
            //if (this->dCurFreq > a)
            //{
            //}
           //this->dCurFreq = AuMin(a, this->dCurFreq);
        }

        AuUInt8 uVecSize {};
        AuUInt64 uVecTable[10];

        AuThreadPrimitives::SpinLock lock;

        AuUInt64 uLast {};

        AuUInt uTotalLifetime {};
        AuInt64 uLastWall {};

        double dCurFreq {};
    };
}