/***
    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 "Process.NT.hpp"
#include "Processes.hpp"
#include <process.h>

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

#include "ArgvQuote.hpp"

#include <Source/IO/FS/FS.hpp>

namespace Aurora::Processes
{
    ProcessImpl::ProcessImpl(const StartupParmaters &params) : startup_(params)
    {
        this->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());
            AuString escaped;
            ArgvQuote(arg, escaped, false);
            this->windowsCli_ += escaped + " ";
        }

        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 HasExited() || TermWinEnumProcesses();
    }

    bool ProcessImpl::HasExited()
    {
        DWORD exitCode;

        if (!GetExitCodeProcess(this->process_, &exitCode))
        {
            return true;
        }

        return exitCode != 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(EStandardHandle stream, const AuMemoryViewStreamWrite &destination, bool nonblock)
    {
        DWORD size = destination.length;
        
        if (!EStandardHandleIsValid(stream) || (stream == EStandardHandle::eStdIn))
        {
            SysPushErrorArg("Invalid Stream");
            return {};
        }

        auto handle = stream == EStandardHandle::eStdError ? this->pipeStdErrRead_ : this->pipeStdOutRead_;
        if (handle == INVALID_HANDLE_VALUE)
        {
            return false;
        }

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

            if (!avail)
            {
                return true;
            }

            size = AuMin(size, avail);            
        }

        if (!destination.ptr)
        {
            destination.outVariable = size;
            return true;
        }

        auto ret = ReadFile(handle, destination.ptr, size, &size, NULL);
        destination.outVariable = size;
        return ret;
    }

    bool ProcessImpl::Write(const AuMemoryViewStreamRead &in)
    {
        if (!in.ptr)
        {
            SysPushErrorArg("Missing pointer to stdin stream section");
            return {};
        }

        DWORD size = in.length;
        if (pipeStdInWrite_ == INVALID_HANDLE_VALUE)
        {
            SysPushErrorUninitialized();
            return false;
        }

        return WriteFile(pipeStdInWrite_, in.ptr, size, &size, NULL) && size == in.length;
    }

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

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

        if (this->type_ == ESpawnType::eSpawnOvermap)
        {
            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;

        #define NEW_NULL_HANDLE                                                                                                                \
            {                                                                                                                                  \
                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)
            {
                NEW_NULL_HANDLE;
                this->pipeStdInRead_ = nulFile;
            }

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

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

        return true;
    }

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

        if (this->type_ == ESpawnType::eSpawnOvermap)
        {
            _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(AuIOFS::NormalizePathRet(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)
            {
                DWORD wr = GetLastError();
                SysPushErrorGen("CreateProcess failed");
                return false;
            }

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

            AuWin32CloseHandle(this->pipeStdOutWrite_);
            AuWin32CloseHandle(this->pipeStdErrWrite_);
            AuWin32CloseHandle(this->pipeStdInRead_);

            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)
    {
        AuSafeDelete<ProcessImpl *>(process);
    }
}