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

    File: AuExit.cpp
    Date: 2022-2-5
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuExit.hpp"
#include <Source/Grug/AuGrug.hpp>
#include "AuMTWatchDog.hpp"

#if defined(AURORA_IS_POSIX_DERIVED)
    #include "AuExit.Unix.hpp"

    namespace Aurora::Processes
    {
        void PosixProcessShutdown();
    }

#endif

#include <Source/Debug/MemoryCrunch.hpp>

namespace Aurora::Console::ConsoleTTY
{
    void LeaveScrollMode();
    void Exit();
}

namespace Aurora::Exit
{
    static AuMutex gMutex;
    static AuList<AuTuple<AuSPtr<IExitSubscriber>, ETriggerLevel>> gTriggerSubscribers;
    static bool gIsAppRunning { true };
    static bool gIsAppForceTerminating { false };

    static void DispatchHandlersForThread(AuThreads::IAuroraThread *pThread, ETriggerLevel level)
    {
        ExitInvoker invoker;
        
        invoker.pCaller = pThread;

        for (const auto &[sub, subLevel] : gTriggerSubscribers)
        {
            if (level == subLevel)
            {
                try
                {
                    sub->OnTrigger(level, &invoker);
                }
                catch (...)
                {
                    // Intentionally left empty. Telemetry hooks will report, if possible.
                }
            }
        }
    }

    static void UnsafeProcessShutdownHook()
    {
    #if defined(AURORA_IS_POSIX_DERIVED)
        Processes::PosixProcessShutdown();
    #endif
    }

    void PostLevel(AuThreads::IAuroraThread *thread, ETriggerLevel level)
    {
        AU_DEBUG_MEMCRUNCH;

        bool bOldTerminatingValue;
        
        {
            AU_LOCK_GLOBAL_GUARD(gMutex);

            bool isTerminate = level == ETriggerLevel::eSafeTermination;
            bool isPreempting {};

            // Prevent double eSafeTermination
            if (isTerminate && gHasSentTerminate)
            {
                isPreempting = true;
            }

            // 
            bOldTerminatingValue = gIsAppRunning;
            if (isTerminate || level == ETriggerLevel::eSigTerminate || level == ETriggerLevel::eSigQuitNow)
            {
                gIsAppRunning = false;
            }

            if (level == ETriggerLevel::eSigQuitNow)
            {
                gIsAppForceTerminating = true;
            }

            static AuUInt32 gProblemCounter = {};

            // Mitigate reused stack, nested try/catch, spam
            if (level == ETriggerLevel::eProblematicEvent)
            {
                if (AuAtomicTestAndSet(&gProblemCounter, 1))
                {
                    return;
                }
            }

            // HACK:
            gHasCanceled = false;

            // Dispatch
            DispatchHandlersForThread(thread, level);

            // ...
            if (level == ETriggerLevel::eProblematicEvent)
            {
                Grug::NotifyGrugOfLogs();
            }
            else
            {
                Grug::GrugFlushWrites();
                Grug::GrugFlushFlushs();

            #if defined(AURORA_PLATFORM_WIN32)
                Aurora::Console::ConsoleTTY::LeaveScrollMode();
            #endif

                Aurora::Console::ConsoleTTY::Exit();
            }

            gProblemCounter = 0;

            // Has already sent eSafeTermination? 
            if (isPreempting)
            {
                return;
            }

            // ...
            gHasSentTerminate |= isTerminate;
        }

        if (gIsAppForceTerminating)
        {
            gHasCanceled = false;
        }

        if ((level == ETriggerLevel::eSigTerminate && !gHasCanceled) ||
            level == ETriggerLevel::eFatalException ||
            level == ETriggerLevel::eSafeTermination||
            level == ETriggerLevel::eSigQuitNow)
        {
            UnsafeProcessShutdownHook();
        }

        // Force exit after calling the subscribers, should the level be eSigTerminate
        if (level == ETriggerLevel::eSigTerminate ||
            level == ETriggerLevel::eSigQuitNow)
        {
            // HACK: 
            if (gHasCanceled && !gIsAppForceTerminating)
            {
                gIsAppRunning = bOldTerminatingValue;
            }
            else
            {
                Process::Exit(0);
            }
        }
    }

    AUKN_SYM bool ExitHandlerAdd(ETriggerLevel level, const AuSPtr<IExitSubscriber> &callback)
    {
        if (!ETriggerLevelIsValid(level))
        {
            return false;
        }
        AU_LOCK_GLOBAL_GUARD(gMutex);
        return AuTryInsert(gTriggerSubscribers, AuMakePair(callback, level));
    }

    AUKN_SYM void ExitHandlerRemove(const AuSPtr<IExitSubscriber> &callback)
    {
        AU_LOCK_GLOBAL_GUARD(gMutex);

        AuRemoveAllIf(gTriggerSubscribers, [=](const auto &entry) -> bool
        {
            return AuGet<0>(entry) == callback;
        });
    }

    AUKN_SYM bool IsAppRunning()
    {
        return gIsAppRunning && !gIsAppForceTerminating;
    }

    AUKN_SYM void CancelExit()
    {
        // HACK:
        gHasCanceled = true;
    }

#if defined(AURORA_PLATFORM_WIN32)

    static void SendExitSignal(Grug::Arrow *)
    {
        PostLevel(AuThreads::GetThread(), Exit::ETriggerLevel::eSigTerminate);
    }

    static void SendExitNowSignal(Grug::Arrow *)
    {
        PostLevel(AuThreads::GetThread(), Exit::ETriggerLevel::eSigQuitNow);
    }

    static void SendTerminateSignalAndBlock()
    {
        static Grug::Arrow arrow;
        Grug::HurlArrow(&arrow, SendExitSignal, {});
        Grug::ArrowWait(&arrow);
    }

    BOOL Win32BasicHandler(DWORD ctrlType)
    {
        if (ctrlType == CTRL_C_EVENT ||
            ctrlType == CTRL_CLOSE_EVENT ||
            ctrlType == CTRL_SHUTDOWN_EVENT)
        {
            Exit::gHasCanceled = false;
            //SendTerminateSignalAndBlock();// for some reason we aren't getting win32 console flushes **reliably** :(
            if (ctrlType == CTRL_C_EVENT)
            {
                SendExitSignal(nullptr);
            }
            else
            {
                SendExitNowSignal(nullptr);
            }
            return !AuExchange(Exit::gHasCanceled, false);
        }

        return true;
    }
#endif

    void InitExit()
    {
        InitWatchdog();

    #if defined(AURORA_IS_POSIX_DERIVED)
        InitUnix();
    #endif

    #if defined(AURORA_PLATFORM_WIN32)
        ::SetConsoleCtrlHandler((PHANDLER_ROUTINE)Win32BasicHandler, TRUE);
    #endif
    }

    void DeinitExit()
    {
    #if defined(AURORA_IS_POSIX_DERIVED)
        DeinitUnix();
    #endif
    }
}