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

    File: ErrorStack.cpp
    Date: 2022-11-29
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "Debug.hpp"
#include "ErrorStack.hpp"

#if defined(AURORA_COMPILER_CLANG)
    // warning: ISO C++20 considers use of overloaded operator '==' (with operand types 'AuSPtr<Aurora::Debug::ThreadMessage>' (aka 'ExSharedPtr<Aurora::Debug::ThreadMessage, std::shared_ptr<ThreadMessage>>') and 'AuSPtr<Aurora::Debug::ThreadMessage>' (aka 'ExSharedPtr<Aurora::Debug::ThreadMessage, std::shared_ptr<ThreadMessage>>')) to be ambiguous despite there being a unique best viable function [-Wambiguous-reversed-operator]
    #pragma clang diagnostic ignored "-Wambiguous-reversed-operator"
    // Yea, I couldn't give less of a nanoshit what some C++20 spec says. Even llvm/clang doesn't care to language police it into a fatal unimplemented compiler condition. So, idc.
#endif

namespace Aurora::Debug
{
    static thread_local AuString tlsLastMessageError;
    static AuString strFailureCategoryCache[128];

    struct ErrorStackAccessor
    {
        void SetNext(ErrorStack *pStack, ErrorStack *pNext)
        {
            pStack->pNext = pNext;
        }

        ErrorStack *GetNext(ErrorStack *pStack)
        {
            return pStack->pNext;
        }

        void SetHead(ErrorStack *pStack, AuSPtr<ThreadMessage> pHead)
        {
            pStack->pHead = pHead;
        }

        AuSPtr<ThreadMessage> GetHead(ErrorStack *pStack)
        {
            return pStack->pHead;
        }

        void SetOOM(ErrorStack *pStack)
        {
            pStack->bOutOfMemory = true;
        }
    };

    AUKN_SYM const AuString &ThreadMessage::ToString()
    {
        static const AuString kUnknownError = "Unknown Error.";
        
        if (this->pStringMessage)
        {
            return *this->pStringMessage;
        }

        if (eFailureCategory)
        {
            auto uIndex = (AuUInt)*eFailureCategory;

            if (AuArraySize(strFailureCategoryCache) <= uIndex)
            {
                return tlsLastMessageError = fmt::format("Debug::EFailureCategory = {}", (AuUInt)*eFailureCategory);
            }
            else
            {
                auto &stringBuffer = strFailureCategoryCache[uIndex];

                if (stringBuffer.size())
                {
                    return stringBuffer;
                }
                else
                {
                    return stringBuffer  = fmt::format("Debug::EFailureCategory = {}", (AuUInt)*eFailureCategory);
                }
            }
        }

        if (optOsErrorCode)
        {
            return tlsLastMessageError = fmt::format("OS  = {}", (AuUInt)*optOsErrorCode);
        }

        return kUnknownError;
    }

    static thread_local ErrorStack *tlsErrorStackBase;

    AUKN_SYM ErrorStack::ErrorStack()
    {
        auto pStack = this;

        if (!tlsErrorStackBase)
        {
            tlsErrorStackBase = pStack;
            return;
        }

        ErrorStackAccessor dumb;
        auto itr = tlsErrorStackBase;
        while (auto pNext = dumb.GetNext(itr))
        {
            itr = pNext;
        }

        dumb.SetNext(itr, pStack);
    }

    AUKN_SYM ErrorStack::~ErrorStack()
    {
        auto pStack = this;

        if (!tlsErrorStackBase)
        {
            return;
        }

        ErrorStackAccessor dumb;
        auto itr = tlsErrorStackBase;

        if (itr == pStack)
        {
            tlsErrorStackBase = nullptr;
            return;
        }

        while (auto pNext = dumb.GetNext(itr))
        {
            if (pNext == pStack)
            {
                dumb.SetNext(pStack, {});
                return;
            }

            itr = pNext;
        }
    }

    static void AddToInstance(ErrorStack *pStack, AuSPtr<ThreadMessage> pMessage)
    {
        ErrorStackAccessor dumb;
        if (!dumb.GetHead(pStack))
        {
            dumb.SetHead(pStack, pMessage);
            return;
        }

        AuSPtr<ThreadMessage> pMessage2 { dumb.GetHead(pStack) };

        if (pMessage2 == pMessage)
        {
            return;
        }

        while (auto pNext = pMessage2->pNextThreadMesage)
        {
            if (pNext == pMessage)
            {
                return;
            }
            pMessage2 = pNext;
        }

        pMessage2->pNextThreadMesage = pMessage;
    }

    //////////////////////////////////////////////////////////////////
    // internal api:

    bool ShouldPushErrorStackInternal()
    {
        return bool(tlsErrorStackBase);
    }

    void PushErrorStackInternal(AuSPtr<ThreadMessage> pMessage)
    {
        ErrorStackAccessor dumb;
        auto itr = tlsErrorStackBase;

        if (itr)
        {
            AddToInstance(itr, pMessage);
            while (auto pNext = dumb.GetNext(itr))
            {
                AddToInstance(itr, pMessage);
                itr = pNext;
            }
        }
    }

    void OnOutOfMemory()
    { 
        ErrorStackAccessor dumb;
        auto itr = tlsErrorStackBase;

        if (itr)
        {
            dumb.SetOOM(itr);
            while (auto pNext = dumb.GetNext(itr))
            {
                dumb.SetOOM(itr);
                itr = pNext;
            }
        }
    }
}