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

    File: ExceptionWatcher.NT.cpp
    Date: 2022-1-26
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "ExceptionWatcher.NT.hpp"
#include <ehdata.h>

#if defined(AURORA_PLATFORM_WIN32)
    #include "ExceptionWatcher.Win32.hpp"
    #include "Stack.Win32.hpp"
#endif

#include "Debug.hpp"
#include <Source/Telemetry/Telemetry.hpp>
#include <Source/Grug/AuGrug.hpp>
#include <Source/Exit/AuExit.hpp>

namespace Aurora::Debug
{
    static std::string kStringRawName = typeid(std::string).raw_name();

    static bool IsReadable(const void *address)
    {
        MEMORY_BASIC_INFORMATION info;

        if (!VirtualQuery(address, &info, sizeof(info)))
        {
            return false;
        }

        if (!info.BaseAddress)
        {
            return false;
        }

        return (info.Protect & (PAGE_READONLY | PAGE_READWRITE)) != 0;
    }

    AuString ReportSEH(HMODULE handle, void *exception, const void *throwInfo, const AuFunction<AuString()> &resolveFallback, const StackTrace &trace, const AuFunction<void(const AuString &)> &prereport)
    {
        AuString message;

        if (handle != INVALID_HANDLE_VALUE)
        {
            try
            {
                const ThrowInfo *pthrowInfo = reinterpret_cast<const ThrowInfo *>(throwInfo);
                auto attribs = pthrowInfo->attributes;

                const auto catchableTypeArray = reinterpret_cast<const CatchableTypeArray *>(reinterpret_cast<AuUInt>(handle) + (AuUInt)(pthrowInfo->pCatchableTypeArray));

                AuString suffix;
                for (int i = 0; i < catchableTypeArray->nCatchableTypes; i++)
                {
                    const auto type = reinterpret_cast<CatchableType *>           (reinterpret_cast<AuUInt>(handle) + (AuUInt)(catchableTypeArray->arrayOfCatchableTypes[i]));
                    const auto descriptor = reinterpret_cast<std::type_info *>    (reinterpret_cast<AuUInt>(handle) + (AuUInt)(type->pType));

                    message += (i == 0 ? "" : AuString(", ")) + descriptor->name(); // __std_type_info_name

                    if (_strnicmp(descriptor->raw_name(), ".?AVException@", 15 - 1) == 0)
                    {
                        auto exception2 = reinterpret_cast<std::exception *>(exception);
                        auto wptr = exception2->what();
                        if (wptr)
                        {
                            suffix = wptr;
                        }
                    }
                    else if (_strnicmp(descriptor->raw_name(), ".PEAD", 5) == 0)
                    {
                        auto possibleStringPointer = reinterpret_cast<const char **>(exception);
                        if (IsReadable(possibleStringPointer))
                        {
                            auto string = *possibleStringPointer;
                            if (IsReadable(string) && (strnlen(string, 4096) < 1024))
                            {
                                suffix = string;
                            }
                        }
                    }
                    else if (_strnicmp(descriptor->raw_name(), kStringRawName.data(), kStringRawName.size()) == 0)
                    {
                        auto possibleStdStringPointer = reinterpret_cast<std::string *>(exception);
                        if (IsReadable(possibleStdStringPointer))
                        {
                            suffix = *possibleStdStringPointer;
                        }
                    }
                }

                if (suffix.size())
                {
                    message += AuString("\r\n    ") + suffix;
                }
            }
            catch (...)
            {

            }
        }

        if (message.find("invalid sto") != AuString::npos) return message;

        try
        {
            if (message.empty() && resolveFallback)
            {
                message = resolveFallback();
            }
        }
        catch (...)
        {

        }

        if (prereport)
        {
            prereport(message);
        }

        try
        {
            Telemetry::NewBlockboxEntry entry;
            entry.type = Telemetry::ENewBlackBoxEntry::eStackWarning;
            entry.stack.fenceId = ReportStackTrace(trace, message);
            entry.stack.backtrace = trace;
            Telemetry::Report(entry);
        }
        catch (...)
        {

        }

        return message;
    }

    static void HandleFatal(bool fatal, _EXCEPTION_POINTERS *pExceptionInfo)
    {
        static bool handlingFatal = false;

    #if defined(AU_ENABLE_NATIVE_MINIDUMP)
        if (!fatal)
        {
            if (IsDebuggerPresent()) __debugbreak();
            else BlackboxReport(pExceptionInfo, false);
        }
        else
        {
            SaveMinidump(pExceptionInfo, true);
        }
    #else
        BlackboxReport(pExceptionInfo, true);
    #endif 
    }

    void PlatformHandleFatal(bool fatal)
    {
        static bool forceFail {false};
        _EXCEPTION_POINTERS ptrs;
        StackTrace ret;
        CONTEXT ctx;
   
        if (!GetThreadContext(GetCurrentThread(), &ctx))
        {
            Debug::Panic();
        }

        if (!AuExchange(forceFail, true))
        {
            Exit::PostLevel(AuThreads::GetThread(), Aurora::Exit::ETriggerLevel::eFatalException);
        }

        ptrs.ExceptionRecord = {};
        ptrs.ContextRecord = &ctx;
        HandleFatal(fatal, &ptrs);
    }

    void InitNT()
    {
        if (!gRuntimeConfig.debug.bEnableInjectedExceptionHandler)
        {
            return;
        }

        // i dont think we need a slow grug path for windows
        // "runs in the same thread context" (- msdn) =/= we will run out of the old threads stack
        // cant be any worse than unix &~ ONSTACK traps (ironically on-stack being shorthand for onstack on an alt heap)

        SetUnhandledExceptionFilter([](_EXCEPTION_POINTERS *pExceptionInfo) -> LONG
        {
            try
            {
                AuLogWarn("Handling fatal NT err exception...");
            }
            catch (...)
            {

            }
            HandleFatal(true, pExceptionInfo);
            return EXCEPTION_EXECUTE_HANDLER;
        });
    }
}

static thread_local AuUInt tlsThrowCounter;

extern "C" AUKN_SYM void __stdcall _ReportMSVCSEH(void *exception, const void *throwInfo, void *caller)
{
    if (!throwInfo)
    {
        return;
    }

    if (!exception)
    {
        return;
    }

    HMODULE handle = 0;

    if (_EH_RELATIVE_TYPEINFO)
    {
        if (!GetModuleHandleExA(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT, reinterpret_cast<LPCSTR>(caller), reinterpret_cast<HMODULE *>(&handle)))
        {
            return;
        }
    }

    if (handle == INVALID_HANDLE_VALUE)
    {
        return;
    }

    // we will probably overflow for a bit if an inner try catch borks up somewhere
    if ((tlsThrowCounter++) == 7)
    {
        tlsThrowCounter--;
        return;
    }

    try
    {
        auto trace = AuDebug::GetStackTrace();

        if (gRuntimeConfig.debug.bPrintExceptionStackTracesOut)
        {
            AuDebug::ReportSEH(handle, exception, throwInfo, {}, trace,
                               [&](const AuString &str)
            {
                AuLogWarn("Local MSVC Exception: 0x{:x}, {}", exception, str.c_str());
                AuLogWarn("{}", StringifyStackTrace(trace));
            });
        }
        else
        {
            AuDebug::ReportSEH(handle, exception, throwInfo, {}, trace,
                               [&](const AuString &str) {});
        }
    }
    catch (...)
    {

    }

    Aurora::Exit::PostLevel(AuThreads::GetThread(), Aurora::Exit::ETriggerLevel::eProblematicEvent);
    tlsThrowCounter--;
}