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

    File: AuCpuTimes.cpp
    Date: 2023-12-30
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuCpuTimes.hpp"

#if defined(__FreeBSD__)

    #include <errno.h>
    #include <sys/sysctl.h>
    #include <sys/resource.h>

#elif defined(AURORA_IS_XNU_DERIVED)

    #include <sys/dkstat.h>

#elif defined(AURORA_IS_LINUX_DERIVED)

    #if !defined(USER_HZ)
        #define USER_HZ 100
    #endif

#endif

namespace Aurora::HWInfo
{
    static AuUInt64 ConvertTicks(AuUInt64 uTicks)
    {
    #if defined(AURORA_IS_MODERNNT_DERIVED)
        return uTicks * 100ull;
    #else
        static const auto kFreq =
        #if defined(AURORA_IS_LINUX_DERIVED)
            USER_HZ
        #else
            CLOCKS_PER_SEC
        #endif
            ;

        if (kFreq == 10000000)
        {
            return uTicks * 100ull;
        }
        else if (kFreq == 1000000)
        {
            return uTicks * 1000ull;
        }
        else if (kFreq == 100000)
        {
            return uTicks * 10000ull;
        }
        else if (kFreq == 10000)
        {
            return uTicks * 100000ull;
        }
        else if (kFreq == 1000)
        {
            return uTicks * 1000000ull;
        }
        else if (kFreq == 100)
        {
            return uTicks * 10000000ull;
        }
        else if (kFreq == 100000000)
        {
            return uTicks * 10ull;
        }
        else if (kFreq == 1000000000ull)
        {
            return uTicks;
        }
        else
        {
            const long long uWhole = (uTicks / kFreq) * 1'000'000'000ull;
            const long long uPart  = (uTicks % kFreq) * 1'000'000'000ull / kFreq;
            return uWhole + uPart;
        }
    #endif
    }

#if defined(__FreeBSD__)

    static int CpuSysctl(const char *pName, void *pBuffer, size_t *pLength)
    {
        int error = sysctlbyname(pName, pBuffer, pLength, NULL, 0);
        if (error != 0 && errno != ENOMEM)
        {
            SysPushErrorGeneric(errno);
            return -1;
        }

        return (error);
    }

    static void PlatformGetCoreTimes(AuList<CpuCoreTime> &times)
    {
        auto uThreads = AuHwInfo::GetCPUInfo().uThreads;

        AuList<long> cpuStates;
        cpuStates.resize((uThreads + 1) * CPUSTATES);

        size_t len { cpuStates.size() * sizeof(long) };
        
        if (CpuSysctl("kern.cp_times", cpuStates.data(), &len) < 0)
        {
            return;
        }

        times.resize(uThreads);
        for (AU_ITERATE_N(uCore, uThreads))
        {
            auto &coreTimes = times[uCore];

            coreTimes.uKernelTime    = cpuStates[(CPUSTATES * uCore) + CP_SYS];
        #if defined(CP_INTR)
            coreTimes.uInterruptTime = cpuStates[(CPUSTATES * uCore) + CP_INTR];
        #endif
            coreTimes.uUserTime      = cpuStates[(CPUSTATES * uCore) + CP_USER];
            coreTimes.uIdleTime      = cpuStates[(CPUSTATES * uCore) + CP_IDLE];

            coreTimes.uIdleTime      = ConvertTicks(coreTimes.uIdleTime);
            coreTimes.uInterruptTime = ConvertTicks(coreTimes.uInterruptTime);
            coreTimes.uKernelTime    = ConvertTicks(coreTimes.uKernelTime);
            coreTimes.uUserTime      = ConvertTicks(coreTimes.uUserTime);

            coreTimes.uUptime       = coreTimes.uKernelTime + coreTimes.uUserTime + coreTimes.uInterruptTime;

            coreTimes.uAllPowerUpTime  = coreTimes.uIdleTime +
                coreTimes.uUptime;

        }
    }

#elif defined(AURORA_IS_LINUX_DERIVED)

    static bool PlatformGetCoreTimes(AuList<CpuCoreTime> &times)
    {
        bool bStatus { true };
        AuString statFile {};

        if (!AuFS::ReadString("/proc/stat", statFile))
        {
            return false;
        }

        AuParse::SplitNewlines(statFile, [&](const AuString &line)
        {
            CpuCoreTime coreTimes;

            if (!AuStartsWith(line, "cpu"))
            {
                return;
            }

            auto line2 = line;
            auto intStrs = AuSplitString(line2, " ");

            intStrs.erase(intStrs.begin());

            if (intStrs.size() > 0)
            {
                if (auto result = AuParse::ParseUInt(intStrs[0]))
                {
                    coreTimes.uUserTime = result.value();
                }
            }

            if (intStrs.size() > 1)
            {
                if (auto result = AuParse::ParseUInt(intStrs[1]))
                {
                    coreTimes.uUserTime += result.value();
                }
            }

            if (intStrs.size() > 2)
            {
                if (auto result = AuParse::ParseUInt(intStrs[2]))
                {
                    coreTimes.uKernelTime = result.value();
                }
            }

            if (intStrs.size() > 3)
            {
                if (auto result = AuParse::ParseUInt(intStrs[3]))
                {
                    coreTimes.uIdleTime = result.value();
                }
            }

            if (intStrs.size() > 4)
            {
                if (auto result = AuParse::ParseUInt(intStrs[4]))
                {
                    coreTimes.uKernelTime += result.value();
                }
            }

            if (intStrs.size() > 5)
            {
                if (auto result = AuParse::ParseUInt(intStrs[5]))
                {
                    coreTimes.uInterruptTime += result.value();
                }
            }

            if (intStrs.size() > 6)
            {
                if (auto result = AuParse::ParseUInt(intStrs[6]))
                {
                    coreTimes.uInterruptTime += result.value();
                }
            }

            for (AU_ITERATE_N_TO_X(i, 7, intStrs.size()))
            {
                if (auto result = AuParse::ParseUInt(intStrs[i]))
                {
                    coreTimes.uKernelTime += result.value();
                }
            }

            coreTimes.uIdleTime      = ConvertTicks(coreTimes.uIdleTime);
            coreTimes.uInterruptTime = ConvertTicks(coreTimes.uInterruptTime);
            coreTimes.uKernelTime    = ConvertTicks(coreTimes.uKernelTime);
            coreTimes.uUserTime      = ConvertTicks(coreTimes.uUserTime);

            coreTimes.uUptime = coreTimes.uKernelTime +
                coreTimes.uUserTime +
                coreTimes.uInterruptTime;

            coreTimes.uAllPowerUpTime = coreTimes.uIdleTime +
                coreTimes.uUptime;

            times.push_back(coreTimes);
        });

        return bStatus;
    }

#elif defined(AURORA_IS_MODERNNT_DERIVED)

    static bool PlatformGetCoreTimes(AuList<CpuCoreTime> &times)
    {
    #if defined(_AU_MASSIVE_CPUID)
        SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION processorInfo[256];
    #else
        SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION processorInfo[128];
    #endif

        ULONG uOutLen {};
        if (FAILED(NtQuerySystemInformation(SystemProcessorPerformanceInformation, 
                                            &processorInfo,
                                            sizeof(processorInfo),
                                            &uOutLen)))
        {
            return false;
        }

        auto uCount = uOutLen / sizeof(SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION);
        
        if (!AuTryResize(times, uCount))
        {
            return false;
        }

        for (AU_ITERATE_N(uCore, uCount))
        {
            auto &coreTimes = times[uCore];

            coreTimes.uIdleTime      = ConvertTicks(processorInfo[uCore].IdleTime.QuadPart);
            coreTimes.uInterruptTime = 0;
            coreTimes.uKernelTime    = ConvertTicks(processorInfo[uCore].KernelTime.QuadPart);
            coreTimes.uUserTime      = ConvertTicks(processorInfo[uCore].UserTime.QuadPart);
            coreTimes.uKernelTime    -= coreTimes.uIdleTime;
                                    
            coreTimes.uUptime = coreTimes.uKernelTime +
                coreTimes.uUserTime +
                coreTimes.uInterruptTime;

            coreTimes.uAllPowerUpTime = coreTimes.uIdleTime +
                coreTimes.uUptime;
        }

        return true;
    }


#elif defined(AURORA_IS_POSIX_DERIVED)

    static bool PlatformGetCoreTimes(AuList<CpuCoreTime> &times)
    {
        return false;
    }

#else

    static bool PlatformGetCoreTimes(AuList<CpuCoreTime> &times)
    {
        return false;
    }

#endif

    AUKN_SYM bool GetPerCoreCPUTime(AuList<CpuCoreTime> &times)
    {
        return PlatformGetCoreTimes(times);
    }
}