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

    File: AuNetResolver.Unix.cpp
    Date: 2022-8-26
    Author: Reece
***/
#include "Networking.hpp"
#include "AuNetResolver.Unix.hpp"
#include "AuNetEndpoint.hpp"
#include <Source/IO/Loop/LSSignalCatcher.Linux.hpp>
#include <Source/IO/Loop/LSEvent.hpp>

#if defined(AURORA_IS_LINUX_DERIVED)
    #define RESOLVER_IS_VERY_FREETARDED
#endif

namespace Aurora::IO::Net
{
    static const auto kMagicSignal = SIGRTMIN + 10 - 6 + 9;
    static AuList<AuWPtr<NetResolver>> tlsResolvers;
    
    struct ThreadLocalCaughtCompletion : Loop::LSSignalCatcher
    {
        ThreadLocalCaughtCompletion(NetResolver *pParent);

        virtual bool OnTrigger(AuUInt handle) override;

        virtual const AuList<AuUInt> &GetHandles() override;
        virtual bool Singular() override;


    private:
        AuList<AuUInt> handles_;
        NetResolver *pParent_;
    };

    ThreadLocalCaughtCompletion::ThreadLocalCaughtCompletion(NetResolver *pParent) :
        LSSignalCatcher({kMagicSignal}),
        pParent_(pParent)
    {
        handles_ = {this->handle, AuStaticCast<AuLoop::LSEvent>(this->pParent_->pEvent)->GetHandle()};
    }

    const AuList<AuUInt> &ThreadLocalCaughtCompletion::GetHandles()
    {
        return this->handles_;
    }

    bool ThreadLocalCaughtCompletion::Singular()
    {
        return false;
    }

    bool ThreadLocalCaughtCompletion::OnTrigger(AuUInt handle)
    {
        if (this->pParent_->CheckAsync())
        {
            if (this->pParent_->pEvent)
            {
                this->pParent_->pEvent->Reset();
            }

            return true;
        }


    // TODO (Reece) urgent: HACK FIX ME
    // Its a slow path so this hack shouldn't matter.
    // We specifically optimize it by keeping the event latched until we
    // specifically receive a poll update, in which case, reset the event,
    // give the shitty glibc freetarded code a chance to catch up, then check.
    // This way, we should never miss an update
    #if 1
        if (handle == handles_[1])
        {
            if (this->pParent_->pEvent)
            {
                this->pParent_->pEvent->Reset();
            }

            for (int i = 0; i < 10; i++)
            {
                AuThreading::ContextYield();
            }

            return this->pParent_->CheckAsync();
        }
    #endif

        return false;
    }
    
    NetResolver::NetResolver(const AuSPtr<INetWorker> &pWorker) :
        pWorker_(pWorker)
    {
        this->pEvent = AuLoop::NewLSEvent(false, false);
    }

    NetResolver::NetResolver(const AuSPtr<INetWorker> &pWorker,
                             const AuSPtr<AuAsync::PromiseCallback<AuList<IPAddress>, NetError>> &pCompletion) :
        pCompletion_(pCompletion),
        pWorker_(pWorker)
    {
        this->pEvent = AuLoop::NewLSEvent(false, false);
    }

    NetResolver::~NetResolver()
    {
    }

    bool NetResolver::Start()
    {
        int iInfoEx { 0 };

        if (this->bA && this->bAAAA)
        {
            infoEx.ai_family = AF_UNSPEC;
        }
        else if (this->bA && !this->bAAAA)
        {
            infoEx.ai_family = AF_INET;
        }
        else if (this->bAAAA)
        {
            infoEx.ai_family = AF_INET6;
        }
        else
        {
            return false;
        }

        sigevent event {0};
        event.sigev_notify = SIGEV_SIGNAL;
        event.sigev_signo = kMagicSignal;
        //event._sigev_un._tid = gettid();

        auto pQueue = AuMakeShared<ThreadLocalCaughtCompletion>(this);
        if (!pQueue)
        {
            SysPushErrorNet("");
            return false;
        }

        if (!pQueue->HasValidHandle())
        {
            SysPushErrorNet("");
            return false;
        }

        this->UpdateTrigger(pQueue);

        auto pBase =  &this->gnuAsyncOperation;
        pBase->ar_request = (addrinfo *)&infoEx;
        pBase->ar_name = hostname.c_str();

        AuTryInsert(tlsResolvers, AuSharedFromThis());
        
        int iStatus = ::getaddrinfo_a(GAI_NOWAIT,
                                      &pBase,
                                      1,
                                      &event);

        switch (iStatus)
        {
            case EAI_AGAIN:
            {
                SysPushErrorNet("Low Resources | Failed to resolve");
                return false;
            }
            case EAI_MEMORY:
            {
                SysPushErrorNet("Out of Memory | Failed to resolve");
                return false;
            }
            case EAI_SYSTEM:
            {
                SysPushErrorNet("Invalid | Failed to resolve");
                return false;
            }
        }

        if (iStatus != 0)
        {
            SysPushErrorNet("{}", iStatus);
            return false;
        }

        return this->BeginOperation(AuSharedFromThis(),
                                    this->pWorker_);

    }

    void NetResolver::SetCompletion(const AuSPtr<AuAsync::PromiseCallback<AuList<IPAddress>, NetError>> &callback)
    {
        this->pCompletion_ = callback;
    }

    void NetResolver::OnOverlappedComplete()
    {
        for (auto itr = tlsResolvers.begin(); itr != tlsResolvers.end(); )
        {
            auto pResolver = (*itr).lock();
            if (!pResolver)
            {
                itr = tlsResolvers.erase(itr);
                continue;
            }

            if (pResolver.get() == this)
            {
                itr = tlsResolvers.erase(itr);
                continue;
            }

            itr++;
        }

        if (AuExchange(this->bHasCompleted_, true))
        {
            return;
        }
        
        if (this->Unpack())
        {
            if (this->pCompletion_)
            {
                try
                {
                    this->pCompletion_->OnSuccess((void *)&this->processedIps_);
                }
                catch (...)
                {
                    SysPushErrorCatch();
                }
            }
        }
        else
        {
            if (this->pCompletion_)
            {
                try
                {
                    this->error_ = ENetworkError::eAsyncError;
                    this->pCompletion_->OnFailure((void *)&this->error_);
                }
                catch (...)
                {
                    SysPushErrorCatch();
                }
            }
        }
    }

    void NetResolver::OnOverlappedFailure(const NetError &error)
    {
        this->error_ = error;
        if (this->pCompletion_)
        {
            try
            {
                this->pCompletion_->OnFailure((void *)&this->error_);
            }
            catch (...)
            {
                SysPushErrorCatch();
            }
        }
        this->bHasCompleted_ = true;
    }

    bool NetResolver::HasFinished()
    {
        return this->bHasCompleted_;
    }

    bool NetResolver::CheckAsync()
    {
        int iStatus = ::gai_error(&this->gnuAsyncOperation);
        return ((iStatus == 0) ||
                (iStatus == EAI_CANCELED));
    }

    void NetResolver::Cancel()
    {
        while (!this->HasComplete())
        {
            int iStatus = ::gai_cancel(&this->gnuAsyncOperation);
            switch (iStatus)
            {
                case EAI_CANCELED:
                case EAI_ALLDONE:
                    break;
                case EAI_NOTCANCELED:
                {
                    IOYield();
                    AuThreading::ContextYield();
                    continue;
                }
            }
        }
    }

    const NetError &NetResolver::GetError()
    {
        return this->error_;
    }

    bool NetResolver::Unpack()
    {
        if (!CheckAsync())
        {
            return false;
        }

        for (auto pItr = this->gnuAsyncOperation.ar_result; pItr; pItr = pItr->ai_next)
        {
            NetEndpoint endpoint;
            AuMemcpy(endpoint.hint, pItr->ai_addr, pItr->ai_addrlen);
            DeoptimizeEndpoint(endpoint);

            if (AuExists(this->processedIps_, endpoint.ip))
            {
                continue;
            }

            if (!AuTryInsert(this->processedIps_, endpoint.ip))
            {
                return false;
            }
        }

        return true;
    }

    static void Annoying(int)
    {
        for (const auto &gawad : tlsResolvers)
        {
            if (auto pResolver = gawad.lock())
            {
                pResolver->pEvent->Set();   
            }
        }
    }

    void InitFreetardedResolver()
    {
        struct sigaction action =
        {
            .sa_handler = Annoying,
            .sa_flags = SA_ONSTACK
        };

        ::sigemptyset(&action.sa_mask);
        ::sigaction(kMagicSignal, &action, nullptr);
    }
}