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

    File: Async.NT.cpp
    Date: 2021-9-13
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "FS.hpp"
#include <Source/IO/Loop/LSHandle.hpp>
//#include "IPCHandle.hpp"
#include "Async.NT.hpp"
#include "FileAdvisory.NT.hpp"
#include <Source/IO/Loop/Loop.hpp>
#include <Source/IO/IPC/IPCPipe.NT.hpp>

namespace Aurora::IO::FS
{
    struct NtAsyncFileTransactionLoopSource : AuLoop::LSHandle
    {
        NtAsyncFileTransactionLoopSource(AuSPtr<NtAsyncFileTransaction> that) : caller_(that), Loop::LSHandle(AuUInt(that->event))
        {}

        virtual bool IsSignaled() override;
        virtual bool OnTrigger(AuUInt handle) override;
        virtual AuLoop::ELoopSource GetType() override;

    private:
        AuWPtr<NtAsyncFileTransaction> caller_;
    };

    bool NtAsyncFileTransactionLoopSource::OnTrigger(AuUInt handle)
    {
        auto lock = caller_.lock();

        if (lock)
        {
            return lock->Complete();
        }

        return true;
    }

    Loop::ELoopSource    NtAsyncFileTransactionLoopSource::GetType()
    {
        return Loop::ELoopSource::eSourceAIO;
    }

    bool NtAsyncFileTransactionLoopSource::IsSignaled()
    {
        auto lock = caller_.lock();
        if (lock)
        {
            return lock->Complete();
        }

        return LSHandle::IsSignaled();
    }

    NtAsyncFileTransaction::~NtAsyncFileTransaction()
    {
        AuWin32CloseHandle(this->event);
    }

    FileHandle::~FileHandle()
    {
        if (this->bNoOwns)
        {
            return;
        }

        if (this->writeHandle != this->handle)
        {
            AuWin32CloseHandle(this->writeHandle);
        }

        this->writeHandle = INVALID_HANDLE_VALUE;
        AuWin32CloseHandle(this->handle);
    }

    bool FileHandle::Init(const AuString &path, EFileOpenMode openMode, bool directIO, EFileAdvisoryLockLevel lock)
    {
        HANDLE fileHandle;

        auto pathex    = NormalizePathRet(path);
        if (pathex.empty())
        {
            return false;
        }

        auto win32Path = Locale::ConvertFromUTF8(pathex);
        if (win32Path.empty())
        {
            return false;
        }

        auto flags = FILE_FLAG_OVERLAPPED;

        if (directIO)
        {
            flags |= FILE_FLAG_NO_BUFFERING;
        }

        fileHandle = INVALID_HANDLE_VALUE;

        switch (openMode)
        {
        case EFileOpenMode::eRead:
        {
            fileHandle = CreateFileW(win32Path.c_str(), GENERIC_READ, NtLockAdvisoryToShare(lock), NULL, OPEN_EXISTING, flags, NULL);
            break;
        }
        case EFileOpenMode::eReadWrite:
        {
            CreateDirectories(pathex, true);
            fileHandle = CreateFileW(win32Path.c_str(), GENERIC_WRITE | GENERIC_READ, NtLockAdvisoryToShare(lock), NULL, OPEN_ALWAYS, flags, NULL);
            if (fileHandle == INVALID_HANDLE_VALUE)
            {
                fileHandle = CreateFileW(win32Path.c_str(), GENERIC_WRITE | GENERIC_READ, NtLockAdvisoryToShare(lock), NULL, CREATE_ALWAYS, flags, NULL);
            }
            break;
        }
        case EFileOpenMode::eWrite:
        {
            CreateDirectories(pathex, true);
            fileHandle = CreateFileW(win32Path.c_str(), GENERIC_WRITE | FILE_READ_ATTRIBUTES, NtLockAdvisoryToShare(lock), NULL, OPEN_ALWAYS, flags, NULL);
            if (fileHandle == INVALID_HANDLE_VALUE)
            {
                fileHandle = CreateFileW(win32Path.c_str(), GENERIC_WRITE | GENERIC_READ, NtLockAdvisoryToShare(lock), NULL, CREATE_ALWAYS, flags, NULL);
            }
            break;
        }
        }

        if (fileHandle == INVALID_HANDLE_VALUE)
        {
            SysPushErrorIO("Missing file: {}", path);
            return {};
        }

        this->directIO = directIO;
        this->handle = fileHandle;
        this->writeHandle = fileHandle;
        this->readOnly = openMode == EFileOpenMode::eRead;
        return true;
    }

    void FileHandle::Init(HANDLE read, HANDLE write)
    {
        this->directIO = true;
        this->handle   = read;
        this->writeHandle = write;
        this->readOnly = false;
    }

    AuSPtr<FileHandle> NtAsyncFileStream::GetHandle()
    {
        return handle_;
    }

    void NtAsyncFileStream::Init(const AuSPtr<FileHandle> &handle)
    {
        this->handle_ = handle;
    }

    AuSPtr<IAsyncTransaction> NtAsyncFileStream::NewTransaction()
    {
        auto shared = AuMakeShared<NtAsyncFileTransaction>();
        if (!shared)
        {
            return {};
        }

        if (!shared->Init(this->handle_))
        {
            return {};
        }

        return shared;
    }

    bool NtAsyncFileStream::BlockingTruncate(AuUInt64 length)
    {
        LARGE_INTEGER i {};
        i.QuadPart = length;

        if (!SetFilePointerEx(this->handle_->handle, i, nullptr, FILE_BEGIN))
        {
            SysPushErrorIO();
            return false;
        }

        return SetEndOfFile(this->handle_->handle);
    }

    bool NtAsyncFileStream::BlockingRead(AuUInt64 offset, const Memory::MemoryViewStreamWrite &parameters)
    {
        LARGE_INTEGER i {};
        i.QuadPart = offset;

        if (this->handle_->bReadLock)
        {
            return false;
        }

        if (!SetFilePointerEx(this->handle_->handle, i, nullptr, FILE_BEGIN))
        {
            SysPushErrorIO();
            return false;
        }

        OVERLAPPED a {};
        a.hEvent = CreateEventA(NULL, true, 0, NULL);

        DWORD read;
        if (!::ReadFile(this->handle_->handle, parameters.ptr, parameters.length, NULL, &a) && 
            ::GetLastError() != ERROR_IO_PENDING)
        {
            SysPushErrorIO();
            ::CloseHandle(a.hEvent);
            return false;
        }

        ::WaitForSingleObject(a.hEvent, 0);
        if (!::GetOverlappedResult(this->handle_->handle, &a, &read, true))
        {
            ::CloseHandle(a.hEvent);
            return false;
        }
        ::CloseHandle(a.hEvent);
        
        parameters.outVariable = read;
        return true;
    }

    bool NtAsyncFileStream::BlockingWrite(AuUInt64 offset, const Memory::MemoryViewStreamRead &parameters)
    {
        LARGE_INTEGER i {};
        i.QuadPart = offset;

        if (this->handle_->bWriteLock)
        {
            return false;
        }

        if (!SetFilePointerEx(this->handle_->handle, i, nullptr, FILE_BEGIN))
        {
            SysPushErrorIO();
            return false;
        }

        OVERLAPPED a {};
        a.hEvent = CreateEventA(NULL, true, 0, NULL);

        DWORD read;
        if (!::WriteFile(this->handle_->writeHandle, parameters.ptr, parameters.length, NULL, &a) &&
            ::GetLastError() != ERROR_IO_PENDING)
        {
            SysPushErrorIO();
            ::CloseHandle(a.hEvent);
            return false;
        }

        ::WaitForSingleObject(a.hEvent, 0);
        if (!::GetOverlappedResult(this->handle_->writeHandle, &a, &read, true))
        {
            ::CloseHandle(a.hEvent);
            return false;
        }

        ::CloseHandle(a.hEvent);
        parameters.outVariable = read;
        return true;
    }

    bool NtAsyncFileTransaction::Init(const AuSPtr<FileHandle> &handle)
    {
        this->pHandle_ = handle;
        this->overlap.hEvent = this->event = CreateEventW(nullptr, true, false, nullptr);
        return this->overlap.hEvent != INVALID_HANDLE_VALUE;
    }
    static bool TranslateNtStatus(NtAsyncFileTransaction *that, BOOL val)
    {
        auto er = GetLastError();
        if (val)
        {
            return true;
        }
        else if (er == ERROR_IO_PENDING)
        {
            return true;
        }
        else if (er == ERROR_BROKEN_PIPE ||
                 er == ERROR_HANDLE_EOF)
        {
            SetEvent(that->event);

            // also required:
            that->bHasFailed    = true; // to pass completion
            that->dwOsErrorCode = er;   // to suppress actual error condition

            auto pipe = that->pNtIpcPipeImpl.lock();

            that->DispatchCb(0);

            if (pipe)
            {
                pipe->OnEndOfReadStream();
            }

            that->pMemoryHold.reset();
            return true;
        }
        else
        {
            that->pPin.reset();
            that->Reset();
            that->dwOsErrorCode = er;
            that->bHasFailed = true;
            SysPushErrorFIO("QoA async FIO error: {} {}", that->GetFileHandle()->path, that->dwOsErrorCode);
            return false;
        }
    }

    static void WINAPI FileOperationCompletion(
        DWORD dwErrorCode,
        DWORD dwNumberOfBytesTransfered,
        LPOVERLAPPED lpOverlapped)
    {
        auto transaction = reinterpret_cast<NtAsyncFileTransaction *>(reinterpret_cast<AuUInt8*>(lpOverlapped) - offsetof(NtAsyncFileTransaction, overlap));
        auto hold = AuExchange(transaction->pPin, {});

        if (dwErrorCode)
        {
            hold->bHasFailed = true;
            hold->dwOsErrorCode = dwErrorCode;
        }
        else if (!hold->dwLastAbstractStat)
        {
            return;
        }

        SetEvent(lpOverlapped->hEvent);
        auto pStupid = AuExchange(hold->pMemoryHold, {});
        hold->CompleteEx(dwNumberOfBytesTransfered);
    }

    bool NtAsyncFileTransaction::IDontWannaUsePorts()
    {
        // TODO: maybe we could use a semaphore counter of read attempts
        // to allow APC callbacks to drag behind

        if (AuExchange(this->pPin, AuSharedFromThis()))
        {
            while (SleepEx(100, true) == WAIT_IO_COMPLETION)
            {

            }

            if (AuExchange(this->pPin, AuSharedFromThis()))
            {
                SysPushErrorUnavailableError();
                return {};
            }
        }

        return true;
    }

    bool NtAsyncFileTransaction::StartRead(AuUInt64 offset, const AuSPtr<AuMemoryViewWrite> &memoryView)
    {
        if (this->isIrredeemable_)
        {
            SysPushErrorIO("Transaction was signaled to be destroyed to reset mid synchronizable operation. You can no longer use this stream object");
            return false;
        }

        if (!IDontWannaUsePorts())
        {
            return false;
        }

        if (!memoryView)
        {
            SysPushErrorArg();
            return {};
        }

        if (this->pMemoryHold)
        {
            SysPushErrorIO("IO Operation in progress");
            return {};
        }

        if (this->pHandle_->bReadLock)
        {
            return false;
        }

        this->bLatch = false;
        ::ResetEvent(this->event);

        this->pMemoryHold = memoryView;
        this->bHasFailed = false;
       
        this->dwLastAbstractStat = memoryView->length;
        this->dwLastAbstractOffset = offset;
        this->dwLastBytes = 0;

        this->overlap.Offset     = AuBitsToLower(offset);
        this->overlap.OffsetHigh = AuBitsToHigher(offset);
       
        auto ret = ::ReadFileEx(this->pHandle_->handle, memoryView->ptr, memoryView->length, &this->overlap, FileOperationCompletion);
        return TranslateNtStatus(this, ret);
    }

    bool NtAsyncFileTransaction::StartWrite(AuUInt64 offset, const AuSPtr<AuMemoryViewRead> &memoryView)
    {
        if (this->isIrredeemable_)
        {
            SysPushErrorIO("Transaction was signaled to be destroyed to reset mid synchronizable operation. You can no longer use this stream object");
            return false;
        }

        if (!IDontWannaUsePorts())
        {
            return false;
        }

        if (!memoryView)
        {
            SysPushErrorArg();
            return {};
        }

        if (this->pMemoryHold)
        {
            SysPushErrorIO("IO Operation in progress");
            return {};
        }

        if (this->pHandle_->bWriteLock)
        {
            return false;
        }

        this->bLatch = false;
        ::ResetEvent(this->event);

        this->bHasFailed = false;

        this->pMemoryHold = memoryView;
        this->dwLastBytes = 0;
        this->dwLastAbstractStat   = memoryView->length;
        this->dwLastAbstractOffset = offset;
        
        this->overlap.Offset     = AuBitsToLower(offset);
        this->overlap.OffsetHigh = AuBitsToHigher(offset);
        auto ret = ::WriteFileEx(this->pHandle_->writeHandle, memoryView->ptr, memoryView->length, &this->overlap, FileOperationCompletion);
        return TranslateNtStatus(this, ret);
    }

    void NtAsyncFileTransaction::DispatchCb(AuUInt32 read)
    {
        this->dwLastAbstractStat = 0;
        this->dwLastBytes = read;

        if (AuExchange(this->bLatch, true))
        {
            return;
        }
        
        this->dwLastBytes = read;

        if (this->pSub_)
        {
            this->pSub_->OnAsyncFileOpFinished(this->dwLastAbstractOffset, read);
        }
    }

    void NtAsyncFileTransaction::Reset()
    {
        if (this->dwLastAbstractStat)
        {
            this->isIrredeemable_ = true;
            this->bHasFailed = true;
            ::CancelIoEx(this->pHandle_->handle, &this->overlap);
            ::SetEvent(this->event);
            this->dwOsErrorCode = ERROR_ABANDONED_WAIT_0;
        }
        else
        {
            ::ResetEvent(this->event);
            this->bHasFailed = false;
        }

        this->dwLastBytes = 0;
        this->dwLastAbstractStat = 0;
    }

    bool     NtAsyncFileTransaction::Failed()
    {
        return this->bHasFailed && 
               this->dwOsErrorCode != ERROR_BROKEN_PIPE &&
               this->dwOsErrorCode != ERROR_HANDLE_EOF;
    }

    AuUInt   NtAsyncFileTransaction::GetOSErrorCode()
    {
        return this->bHasFailed ? this->dwOsErrorCode : ERROR_SUCCESS;
    }

    bool NtAsyncFileTransaction::CompleteEx(AuUInt completeRoutine)
    {
        DWORD read {};

        this->dwLastAbstractStat = 0;

        if (this->isIrredeemable_)
        {
            ::ResetEvent(this->event);
            return true;
        }

        if (!completeRoutine)
        {
            if ((this->bHasFailed) ||
                (this->dwLastBytes))
            {
                return true;
            }

            if (::GetOverlappedResult(this->pHandle_->handle,
                                      &this->overlap,
                                      &read,
                                      false))
            {
                DispatchCb(read);
                return read;
            }
        }
        else
        {
            if (this->dwOsErrorCode == ERROR_BROKEN_PIPE ||
                this->dwOsErrorCode == ERROR_HANDLE_EOF)
            {
                auto pipe = this->pNtIpcPipeImpl.lock();

                DispatchCb(0);

                if (pipe)
                {
                    pipe->OnEndOfReadStream();
                }
            }
            else
            {
                DispatchCb(completeRoutine);
            }

            return true;
        }

        return false;
    }

    bool NtAsyncFileTransaction::Complete()
    {
        return CompleteEx(false);
    }

    AuUInt32 NtAsyncFileTransaction::GetLastPacketLength()
    {
        return this->dwLastBytes;
    }
    
    void NtAsyncFileTransaction::SetCallback(const AuSPtr<IAsyncFinishedSubscriber> &sub)
    {
        this->pSub_ = sub;
    }
    
    bool NtAsyncFileTransaction::Wait(AuUInt32 timeout) 
    {
        if (this->bLatch)
        {
            return true;
        }

        DWORD ret;
        do
        {
            ret = ::WaitForSingleObjectEx(this->event, timeout ? timeout : INFINITE, true);
        }
        while (ret == WAIT_IO_COMPLETION);
        
        if (ret == WAIT_OBJECT_0)
        {
            return Complete();
        }
        return false;
    }

    HANDLE NtAsyncFileTransaction::GetHandle()
    {
        return this->event;
    }

    AuSPtr<FileHandle> NtAsyncFileTransaction::GetFileHandle()
    {
        return this->pHandle_;
    }

    AuSPtr<AuLoop::ILoopSource> NtAsyncFileTransaction::NewLoopSource()
    {
        return AuMakeShared<NtAsyncFileTransactionLoopSource>(AuSharedFromThis());
    }

    AUKN_SYM IAsyncFileStream *OpenAsyncNew(const AuString &path, EFileOpenMode openMode, bool directIO, EFileAdvisoryLockLevel lock)
    {
        AuSPtr<FileHandle> fileHandle;
        NtAsyncFileStream *stream;

        if (path.empty())
        {
            SysPushErrorParam("Empty path");
            return {};
        }

        if (!EFileOpenModeIsValid(openMode))
        {
            SysPushErrorParam("Invalid open mode");
            return {};
        }

        fileHandle = AuMakeShared<FileHandle>();
        if (!fileHandle->Init(path, openMode, directIO, lock))
        {
            return {};
        }

        stream = _new NtAsyncFileStream();
        if (!stream)
        {
            return {};
        }

        stream->Init(fileHandle);
       
        return stream;
    }

    AUKN_SYM void OpenAsyncRelease(IAsyncFileStream *handle)
    {
        AuSafeDelete<NtAsyncFileStream *>(handle);
    }
}