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

    File: AuLogClasses.cpp
    Date: 2023-3-22
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuLogClasses.hpp"

namespace Aurora::Logging
{
    static const AuUInt8 kAvailableSlots = AuLog::kLogLevelMax - AuLog::kLogLevelUsr;
    static AuUInt32 gAtomicInUseCount {};
    static AuUInt32 gInUseMap[kAvailableSlots / 8] {};
    static AuString gStringMap[kAvailableSlots];
    static AuUInt32 gIterator {};
    static AuThreadPrimitives::MutexSOO gMutex;

    static const auto kBitsPerWord = 8 * sizeof(*gInUseMap);

    AUKN_SYM bool LogClassInUse(AuUInt8 uIndex);

    static bool TryAcquire(AuUInt8 uIdx)
    {
        if (AuAtomicSet(&gInUseMap[uIdx / kBitsPerWord], uIdx % kBitsPerWord))
        {
            return false;
        }

        AuAtomicAdd(&gAtomicInUseCount, 1u);
        return true;
    }

    static void Release(AuUInt8 uIdx)
    {
        if (AuAtomicUnset(&gInUseMap[uIdx / kBitsPerWord], uIdx % kBitsPerWord))
        {
            AuAtomicSub(&gAtomicInUseCount, 1u);

            AU_LOCK_GUARD(gMutex);

            if (!LogClassInUse(uIdx + AuLog::kLogLevelUsr))
            {
                gStringMap[uIdx].clear();
            }
        }
    }

    static void SetString(AuUInt8 uIdx, const AuString &str)
    {
        AU_LOCK_GUARD(gMutex);
        gStringMap[uIdx] = str;
    }

    static AuResult<AuUInt8> TryAcquire()
    {
        auto uFirstGuess = (AuAtomicAdd(&gIterator, 1u) - 1) % kAvailableSlots;

        if (!TryAcquire(uFirstGuess))
        {
            for (AU_ITERATE_N(i, kAvailableSlots))
            {
                auto uIndex = (i + uFirstGuess) % kAvailableSlots;
                if (TryAcquire(uIndex))
                {
                    gIterator = uIndex;
                    return AuUInt8(uIndex);
                }
            }

            return {};
        }
        else
        {
            return AuUInt8(uFirstGuess);
        }
    }

    AUKN_SYM void LogClassAssociateName(AuUInt8 uIndex, const AuString &str)
    {
        uIndex -= AuLog::kLogLevelUsr;

        if (uIndex >= kAvailableSlots)
        {
            return;
        }

        SetString(uIndex, str);
    }

    AUKN_SYM const AuString &LogClassGetNameUnsafe(AuUInt8 uIndex)
    {
        uIndex -= AuLog::kLogLevelUsr;

        SysAssertDbg(uIndex < kAvailableSlots);

        return gStringMap[uIndex];
    }

    AUKN_SYM AuString LogClassGetNameSafe(AuUInt8 uIndex)
    {
        AU_LOCK_GUARD(gMutex);

        uIndex -= AuLog::kLogLevelUsr;

        if (uIndex >= kAvailableSlots)
        {
            return {};
        }

        return gStringMap[uIndex];
    }

    AUKN_SYM void LogClassRelease(AuUInt8 uIndex)
    {
        uIndex -= AuLog::kLogLevelUsr;

        if (uIndex >= kAvailableSlots)
        {
            return;
        }

        Release(uIndex);
    }

    AUKN_SYM AuResult<AuUInt8> LogClassGetNext()
    {
        auto uRes = TryAcquire();
        if (uRes)
        {
            return AuUInt8(uRes.value() + AuLog::kLogLevelUsr);
        }

        return {};
    }

    AUKN_SYM bool LogClassInUse(AuUInt8 uIndex)
    {
        uIndex -= AuLog::kLogLevelUsr;

        if (uIndex >= kAvailableSlots)
        {
            return false;
        }

        return AuTestBit(gInUseMap[uIndex / kBitsPerWord], uIndex % kBitsPerWord);
    }

    AUKN_SYM AuUInt8 LogClassTotalAvailable()
    {
        return kAvailableSlots;
    }

    AUKN_SYM AuUInt8 LogClassTotalInUse()
    {
        return gAtomicInUseCount;
    }
}