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

    File: Process.NT.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "Processes.hpp"
#include "Process.Win32.hpp"
#include <process.h>

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

namespace Aurora::Processes
{
    class ProcessImpl : public IProcess
    {
    public:
        ProcessImpl(const StartupParmaters &params);
        ~ProcessImpl();

        bool TermWinEnumProcesses();

        bool TryKill() override;
        bool HasExited();

        AuUInt GetProcessId() override;

        bool Terminate() override;
        AuSPtr<Threading::IWaitable> AsWaitable() override;
        AuSInt GetExitCode() override;

        void ShutdownPipes();
        
        bool Read(bool error, void *buffer, AuUInt32 &len) override;
        bool Read(void *buffer, AuUInt32 &len, bool errorStream, bool nonblock) override;

        bool Write(const void *buffer, AuUInt32 len) override;

        bool Start() override;

        bool Init();

    private:
        
        HANDLE pipeStdOutRead_  {INVALID_HANDLE_VALUE};
        HANDLE pipeStdOutWrite_ {INVALID_HANDLE_VALUE};
        HANDLE pipeStdErrRead_  {INVALID_HANDLE_VALUE};
        HANDLE pipeStdErrWrite_ {INVALID_HANDLE_VALUE};
        HANDLE pipeStdInRead_   {INVALID_HANDLE_VALUE};
        HANDLE pipeStdInWrite_  {INVALID_HANDLE_VALUE};
        
        StartupParmaters startup_;
        ESpawnType type_;
        
        AuList<const char *> cargs_;
        AuString windowsCli_;
        
        AuThreads::ThreadUnique_t thread_;
        HANDLE process_ {INVALID_HANDLE_VALUE};
        HANDLE hthread_ {INVALID_HANDLE_VALUE};
        AuSInt exitCode_;
    };


    ProcessImpl::ProcessImpl(const StartupParmaters &params) : startup_(params)
    {
        startup_.args.insert(startup_.args.begin(), startup_.process);
               
        // ehhhh https://github.com/tritao/WindowsSDK/blob/07983c7ba4f6861d15e23f195744c60c0c249ce0/SDKs/SourceDir/Windows%20Kits/10/Source/10.0.17763.0/ucrt/exec/cenvarg.cpp#L23
        for (const auto &arg : this->startup_.args)
        {
            this->cargs_.push_back(arg.c_str());
            this->windowsCli_ += arg + " ";
        }

        this->cargs_.push_back(nullptr);
        this->windowsCli_.resize(this->windowsCli_.size() - 1);
        this->type_ = params.type;
    }

    ProcessImpl::~ProcessImpl()
    {
        if (this->type_ == ESpawnType::eSpawnChildProcessWorker)
        {
            TryKill();
            Terminate();
        }

        if (this->thread_)
        {
            this->thread_.reset();
        }

        AuWin32CloseHandle(this->process_);
        AuWin32CloseHandle(this->hthread_);

        ShutdownPipes();
    }

    AuUInt ProcessImpl::GetProcessId()
    {
        if (this->process_ == INVALID_HANDLE_VALUE)
        {
            return {};
        }

        return ::GetProcessId(this->process_);
    }

    bool ProcessImpl::TermWinEnumProcesses()
    {
    #if defined(AURORA_PLATFORM_WIN32)
        return SendExitSignal(this->process_);
    #else
        return false;
    #endif
    }

    bool ProcessImpl::TryKill()
    {
        return TermWinEnumProcesses();
    }

    bool ProcessImpl::HasExited()
    {
        DWORD a;
        if (!GetExitCodeProcess(this->process_, &a)) return true;
        return  a != STILL_ACTIVE;
    }

    bool ProcessImpl::Terminate()
    {
        if (this->process_ != INVALID_HANDLE_VALUE)
        {
            return false;
        }

        return TerminateProcess(this->process_, 0) || HasExited();
    }

    AuSPtr<Threading::IWaitable> ProcessImpl::AsWaitable()
    {
        if (!this->thread_) return nullptr;
        return this->thread_->AsWaitable();
    }

    AuSInt ProcessImpl::GetExitCode()
    {
        return this->exitCode_;
    }

    void ProcessImpl::ShutdownPipes()
    {
        AuWin32CloseHandle(this->pipeStdOutRead_);
        AuWin32CloseHandle(this->pipeStdOutWrite_);
        AuWin32CloseHandle(this->pipeStdErrRead_);
        AuWin32CloseHandle(this->pipeStdErrWrite_);
        AuWin32CloseHandle(this->pipeStdInRead_);
        AuWin32CloseHandle(this->pipeStdInWrite_);
    }

    bool ProcessImpl::Read(bool error, void *buffer, AuUInt32 &len)
    {
        return Read(buffer, len, error, false);
    }

    bool ProcessImpl::Read(void *buffer, AuUInt32 &len, bool errorStream, bool nonblock)
    {
        DWORD size = AuExchange(len, 0);
        
        auto handle = errorStream ? pipeStdErrRead_ : pipeStdOutRead_;
        if (handle == INVALID_HANDLE_VALUE)
        {
            return false;
        }

        if (nonblock)
        {
            DWORD avail {};
            if (!PeekNamedPipe(handle, NULL, NULL, NULL, &avail, NULL))
            {
                return false;
            }

            if (!avail)
            {
                return true;
            }

            size = AuMin(size, avail);            
        }

        auto ret = ReadFile(handle, buffer, size, &size, NULL);
        len = size;
        return ret;
    }

    bool ProcessImpl::Write(const void *buffer, AuUInt32 len)
    {
        DWORD size = len;
        if (pipeStdInWrite_ == INVALID_HANDLE_VALUE) return false;
        return WriteFile(pipeStdInWrite_, buffer, size, &size, NULL) && size == len;
    }


    bool ProcessImpl::Init()
    {
        SECURITY_ATTRIBUTES saAttr {};

        saAttr.nLength = sizeof(SECURITY_ATTRIBUTES);
        saAttr.bInheritHandle = TRUE;

        if (this->type_ == ESpawnType::eSpawnAtomicOvermap)
        {
            return true;
        }

        if (this->process_ != INVALID_HANDLE_VALUE)
        {
            return false;
        }

        this->exitCode_ = 0x10110100;
        if (this->startup_.fwdOut)
        {
            if (!CreatePipe(&pipeStdOutRead_, &pipeStdOutWrite_, &saAttr, 0))
            {
                return false;
            }

            if (!SetHandleInformation(pipeStdOutRead_, HANDLE_FLAG_INHERIT, 0))
            {
                return false;
            }
        }

        if (this->startup_.fwdErr)
        {
            if (!CreatePipe(&pipeStdErrRead_, &pipeStdErrWrite_, &saAttr, 0))
            {
                return false;
            }

            if (!SetHandleInformation(pipeStdErrRead_, HANDLE_FLAG_INHERIT, 0))
            {
                return false;
            }
        }

        if (this->startup_.fwdIn)
        {
            if (!CreatePipe(&pipeStdInRead_, &pipeStdInWrite_, &saAttr, 0))
            {
                return false;
            }

            if (!SetHandleInformation(pipeStdInWrite_, HANDLE_FLAG_INHERIT, 0))
            {
                return false;
            }
        }

        if (this->startup_.noShowConsole)
        {
            HANDLE nulFile = INVALID_HANDLE_VALUE;

            // I dont want to move the other SetHandleInformations down below the if block above is, just to find out double SetHandleInfo with the same input params results in a return false condition
            // This will do for.now
        #define CHK_NUL                                                                                                                        \
            if (nulFile == INVALID_HANDLE_VALUE)                                                                                               \
            {                                                                                                                                  \
                nulFile = CreateFileA("nul:", GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL); \
                SetHandleInformation(nulFile, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT);                                                       \
            }

            if (this->pipeStdInRead_ == INVALID_HANDLE_VALUE)
            {
                CHK_NUL;
                this->pipeStdInRead_ = nulFile;
            }

            if (this->pipeStdErrWrite_ == INVALID_HANDLE_VALUE)
            {
                CHK_NUL;
                this->pipeStdErrWrite_ = nulFile;
            }

            if (this->pipeStdOutWrite_ == INVALID_HANDLE_VALUE)
            {
                CHK_NUL;
                this->pipeStdOutWrite_ = nulFile;
            }
        }

        return true;
    }

    bool ProcessImpl::Start()
    {
        if (this->process_ != INVALID_HANDLE_VALUE)
        {
            return false;
        }

        if (this->type_ == ESpawnType::eSpawnAtomicOvermap)
        {
            _spawnv(_P_OVERLAY, this->startup_.process.c_str(), this->cargs_.data());
            SysPushErrorGen("_spawnv didn't overwrite the process map, given {} ({})", this->startup_.process, this->windowsCli_);
            return false;
        }

        PROCESS_INFORMATION processInfo = { 0 };
        {
            STARTUPINFOW startupInfo = { 0 };
            startupInfo.cb = sizeof(startupInfo);
            
            bool inheritHandles = this->startup_.fwdIn || this->startup_.fwdErr || this->startup_.fwdOut || this->startup_.noShowConsole;

            startupInfo.hStdInput  = pipeStdInRead_;
            startupInfo.hStdError  = pipeStdErrWrite_;
            startupInfo.hStdOutput = pipeStdOutWrite_;
            startupInfo.dwFlags   |= (inheritHandles ? STARTF_USESTDHANDLES : 0);

            auto result = CreateProcessW(Locale::ConvertFromUTF8(this->startup_.process).c_str(),
                                         Locale::ConvertFromUTF8(this->windowsCli_).data(),
                                         NULL, NULL, inheritHandles,
                                         this->startup_.noShowConsole ? CREATE_NO_WINDOW : NULL, // yea we can keep CREATE_NO_WINDOW on for non-console apps. its legal -> https://docs.microsoft.com/en-us/windows/win32/procthread/process-creation-flags
                                         NULL, NULL, &startupInfo, &processInfo);

            if (!result)
            {
                SysPushErrorGen("CreateProcess failed");
                return false;
            }

            this->process_ = processInfo.hProcess;
            this->hthread_ = processInfo.hThread;

            AuWin32CloseHandle(this->pipeStdOutRead_);
            AuWin32CloseHandle(this->pipeStdErrRead_);
            AuWin32CloseHandle(this->pipeStdInWrite_);

            if (this->type_ == ESpawnType::eSpawnChildProcessWorker)
            {
            #if defined(AURORA_PLATFORM_WIN32)
                AssignJobWorker(processInfo.hProcess);
            #endif
            }
        }

        // TODO: delegate to a singular worker thread
        auto a = [=]()
        {
            WaitForSingleObject(processInfo.hProcess, INFINITE);

            DWORD exitCode;
            auto result = GetExitCodeProcess(processInfo.hProcess, &exitCode);
            this->exitCode_ = exitCode;
        };

        this->thread_ = AuThreads::ThreadUnique(AuThreads::ThreadInfo(
            AuMakeShared<AuThreads::IThreadVectorsFunctional>(AuThreads::IThreadVectorsFunctional::OnEntry_t(std::bind(a)),
                                                              AuThreads::IThreadVectorsFunctional::OnExit_t{})
        ));
        
        if (!this->thread_)
        {
            return false;
        }

        this->thread_->Run();
        return true;
    }

    AUKN_SYM IProcess *SpawnNew(const StartupParmaters &params)
    {
        try
        {
            auto hi = _new ProcessImpl(params);
            if (!hi) return {};

            if (!hi->Init())
            {
                delete hi;
                return {};
            }

            return hi;
        }
        catch (...)
        {
            return {};
        }
    }

    AUKN_SYM void SpawnRelease(IProcess *process)
    {
        SafeDelete<ProcessImpl *>(process);
    }
}