/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: Debug.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "Debug.hpp"
#include <Source/Telemetry/Telemetry.hpp>

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

namespace Aurora::Debug
{
    static StackTrace gLastStackTrace;
    static AuUInt32 gStackTraceFence;
    static AuUInt32 gFenceId;
    static AuThreadPrimitives::SpinLock gLock;
    static AuString gLastExceptionMessage;
    static AuUInt32 gFenceOSError = -1;

    AuUInt32 GetOSErrorFence()
    {
        return gFenceOSError;
    }

#if defined(AURORA_IS_MODERNNT_DERIVED)

    AuString GetOSErrorStringWin32(DWORD error)
    {
        AuString ret;
    #if defined(AURORA_PLATFORM_WIN32)
        char *err = nullptr;

        if (!FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
            NULL,
            error,
            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
            (LPTSTR)&err,
            0,
            NULL))
        {
            return {};
        }
        
        ret = err;
        LocalFree(err);
    #endif
        return ret;
    }

    AuOptional<OSError_t> TryFetchOSError()
    {
        static OSError_t lastError{};
        
        OSError_t ret{};
        
        ret.first = GetLastError();
        if ((ret.first == ERROR_SUCCESS) ||
            (ret.first == WSAEWOULDBLOCK))
        {
            return {};
        }
        
        if (lastError.first == ret.first)
        {
            return lastError;
        }
        
        ret.second = GetOSErrorStringWin32(lastError.first);
        
        gFenceOSError++;
        gFenceId++;
        return lastError = ret;
    }


    AuOptional<OSError_t> TryGetOrFetchOSError()
    {
        static AuOptional<OSError_t> lastErrorError;
        static AuOptional<AuUInt32> lastErrorFence;

        AuOptional<OSError_t> tempError = TryFetchOSError();

        if (!tempError)
        {
            return lastErrorError;
        }

        if (lastErrorFence)
        {
            if (lastErrorFence.value() != GetOSErrorFence())
            {
                SetLastError(ERROR_SUCCESS);
                Telemetry::InsertOSError(tempError.value());
            }
        }

        lastErrorFence = GetOSErrorFence();
        lastErrorError = tempError;
        return tempError;
    }

#else
    
    AuOptional<OSError_t> TryFetchOSError()
    {
        return {};
    }

    AuOptional<OSError_t> TryGetOrFetchOSError()
    {
        return {};
    }

#endif

    static AuUInt32 gFenceCError = -1;
    AuUInt32 GetCErrorFence()
    {
        return gFenceCError;
    }

    AuOptional<AuUInt32> TryFetchCError()
    {
        static AuUInt32 lastError = 0;
        
        auto errorNumber = errno;
        if (!errorNumber)
        {
            return {};
        }

        if (lastError == errorNumber)
        {
            return errorNumber;
        }
        
        gFenceCError++;
        gFenceId++;
        return lastError = errorNumber;
    }

    AuOptional<AuUInt32> TryGetOrFetchCError()
    {
        static AuOptional<AuUInt32> lastErrorError;
        static AuOptional<AuUInt32> lastErrorFence;

        AuOptional<AuUInt32> tempError = TryFetchCError();

        if (!tempError)
        {
            return lastErrorError;
        }

        if (lastErrorFence)
        {
            if (lastErrorFence.value() != GetCErrorFence())
            {
                errno = 0;
                Telemetry::InsertCError(tempError.value());
            }
        }

        lastErrorFence = GetCErrorFence();
        lastErrorError = tempError;
        return tempError;
    }

    void ReportStackTrace(const StackTrace& trace, const AuString& message)
    {
        AU_LOCK_GUARD(gLock);
        gLastStackTrace = trace;
        gLastExceptionMessage = message;
        gStackTraceFence++;
        gFenceId++;
    }

    AuUInt32 GetFenceId()
    {
        return gFenceId;
    }

    AUKN_SYM AuString GetLastErrorStack()
    {
        return StringifyStackTrace(GetLastStackTrace());
    }

    AUKN_SYM StackTrace GetLastStackTrace()
    {
        AU_LOCK_GUARD(gLock);
        return gLastStackTrace;
    }

    AUKN_SYM AuString GetLastException()
    {
        AU_LOCK_GUARD(gLock);
        return gLastExceptionMessage;
    }

    AUKN_SYM OSError_t GetLastSystemMessage()
    {
        return TryGetOrFetchOSError().value_or(OSError_t{});
    }

    AUKN_SYM void PrintError()
    {
        AuUInt32 rng = GetFenceId();

        Telemetry::InsertManualFence(rng);
        
        static AuUInt32 cLastFence = 0;
        auto cFence = GetCErrorFence();
        auto cError = TryGetOrFetchCError();
        if ((cError) && (cFence != cLastFence))
        {
            LogWarn("Language Error: {} ({})", strerror(*cError), *cError);
            cLastFence = cFence;
        }
        
        static AuUInt32 osLastFence = 0;
        auto osFence = GetOSErrorFence();
        auto osError = TryGetOrFetchOSError();
        if ((osError) && (osFence != osLastFence))
        {
            LogWarn("Operating System Error: {} (0x{:x})", osError->second, osError->first);
            osLastFence = osFence;
        }

        Telemetry::InsertManualFence(rng);
    }
    
    void CheckErrors()
    {
        AuUInt32 rng = GetFenceId();
        Telemetry::InsertManualFence(rng);
        TryGetOrFetchCError();
        TryGetOrFetchOSError();
        Telemetry::InsertManualFence(rng);
    }

    AUKN_SYM void _PushError(AuUInt address, EFailureCategory category, const char *msg)
    {
        LastError error {address, category, msg ? msg : ""};
    
        // Oi, developer
    #if defined(DEBUG)
        DebugBreak();
    #endif

        // Cry about it to telemetry with other errors if available
        AuUInt32 rng = GetFenceId();
        Telemetry::InsertManualFence(rng);
        Telemetry::InsertMsgError(error);
        TryGetOrFetchCError();
        TryGetOrFetchOSError();
        Telemetry::InsertManualFence(rng);
        
        // Is anyone listening?
        // Print to console if internal
        
        // Eh, dont spam nested to a logger if its not going to make sense to a normie
        if ((category == EFailureCategory::kFailureNested) && (msg == nullptr))
        {
            return;
        }

    #if defined(DEBUG) || defined(STAGING)
        PrintError();
        LogWarn("ERROR: {}", error.dbg);
    #endif
    }

    AUKN_SYM AuString StackTraceEntry::Stringify() const
    {
        const auto frame = *this;
        AuString   backTraceBuffer;

        backTraceBuffer.reserve(512 - 32); // 512 seems like a nice length minus some overhead for a bucket allocator

        backTraceBuffer += fmt::format("\tAddress: {:x}", frame.address);

        if (frame.module)
        {
            auto modName = frame.module.value();
            if (modName.size())
            {
                backTraceBuffer += fmt::format(" within {}", modName);
            }
            else
            {
                backTraceBuffer += ", invalid module";
            }
        }
        else
        {
            backTraceBuffer += ", unknown module";
        }

        if (frame.label)
        {
            backTraceBuffer += fmt::format(" ({}) \n", frame.label.value());
        }
        else
        {
            backTraceBuffer += ", unknown function\n";
        }
            
        if (frame.file)
        {
            const auto &re = frame.file.value();
            backTraceBuffer += fmt::format("\t\t{}:{} ({}) \n", std::get<0>(re), std::get<1>(re), std::get<2>(re));
        }
        else
        {
            backTraceBuffer += "\t\t[proprietary]\n";
        }

        return backTraceBuffer;
    }

    AUKN_SYM AuString StringifyStackTrace(const StackTrace &backtrace)
    {
        AuString     backTraceBuffer;

        backTraceBuffer.reserve(2048);

        backTraceBuffer += "Unwinding call frame:";

        for (const auto &frame : backtrace)
        {
            backTraceBuffer += "\n";
            backTraceBuffer += frame.Stringify();
        }

        return backTraceBuffer;
    }
    
    void InitDebug()
    {
    #if defined(AURORA_PLATFORM_WIN32)
        InitWin32();
    #endif
    }
}