/***
    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 "Async.NT.hpp"
#include "FileAdvisory.NT.hpp"
#include <Source/Loop/Loop.hpp>
#include <Source/Loop/LSHandle.hpp>

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

        virtual bool IsSignaled() override;
        virtual bool OnTrigger(AuUInt handle) override;
        virtual Loop::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->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:
        case EFileOpenMode::eWrite:
        {
            CreateDirectories(pathex, true);
            fileHandle = CreateFileW(win32Path.c_str(), (openMode == EFileOpenMode::eReadWrite) ? (GENERIC_WRITE | GENERIC_READ) : GENERIC_WRITE, 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 (!SetFilePointerEx(this->handle_->handle, i, nullptr, FILE_BEGIN))
        {
            SysPushErrorIO();
            return false;
        }

        DWORD read;
        if (!::ReadFile(this->handle_->handle, parameters.ptr, parameters.length, &read, nullptr))
        {
            SysPushErrorIO();
            return false;
        }
        parameters.outVariable = read;
        return true;
    }

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

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

        DWORD read;
        if (!::WriteFile(this->handle_->handle, parameters.ptr, parameters.length, &read, nullptr))
        {
            SysPushErrorIO();
            return false;
        }
        parameters.outVariable = read;
        return true;
    }

    bool NtAsyncFileTransaction::Init(const AuSPtr<FileHandle> &handle)
    {
        this->handle_ = 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)
    {
        if ((val) || 
            (!val && (GetLastError() == ERROR_IO_PENDING)))
        {
            return true;
        }
        else
        {
            that->pin_.reset();
            that->Reset();
            SysPushErrorFIO("Async FIO error: {} {}", that->GetFileHandle()->path, GetLastError());
            return false;
        }
    }

    static VOID WINAPI GenericCompletionRoutine(
        _In_    DWORD dwErrorCode,
        _In_    DWORD dwNumberOfBytesTransfered,
        _Inout_ LPOVERLAPPED lpOverlapped
    )
    {
        auto transaction = reinterpret_cast<NtAsyncFileTransaction *>(reinterpret_cast<AuUInt8*>(lpOverlapped) - offsetof(NtAsyncFileTransaction, overlap_));
        auto hold = AuExchange(transaction->pin_, {});
        hold->Complete();
    }

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

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

            }

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

        return true;
    }

    bool NtAsyncFileTransaction::StartRead(AuUInt64 offset, const AuSPtr<AuMemoryViewWrite> &memoryView)
    {
        if (!IDontWannaUsePorts())
        {
            return false;
        }

        this->latch_ = false;
        ::ResetEvent(this->event_);

        this->memoryHold_ = memoryView;
       
        this->lastAbstractStat_ = memoryView->length;
        this->lastAbstractOffset_ = offset;
       
        this->overlap_.Offset = offset & 0xFFFFFFFF;
        this->overlap_.OffsetHigh = (offset >> 32) & 0xFFFFFFFF;
       
        auto ret = ::ReadFileEx(this->handle_->handle, memoryView->ptr, memoryView->length, &overlap_, GenericCompletionRoutine);
        return TranslateNtStatus(this, ret);
    }

    bool NtAsyncFileTransaction::StartWrite(AuUInt64 offset, const AuSPtr<AuMemoryViewRead> &memoryView)
    {
        if (!IDontWannaUsePorts())
        {
            return false;
        }

        this->latch_ = false;
        ::ResetEvent(this->event_);

        this->memoryHold_ = memoryView;
        
        this->lastAbstractStat_ = memoryView->length;
        this->lastAbstractOffset_ = offset;
        
        this->overlap_.Offset = offset & 0xFFFFFFFF;
        this->overlap_.OffsetHigh = (offset >> 32) & 0xFFFFFFFF;
        auto ret = ::WriteFileEx(this->handle_->writeHandle, memoryView->ptr, memoryView->length, &overlap_, GenericCompletionRoutine);
        return TranslateNtStatus(this, ret);
    }

    void NtAsyncFileTransaction::DispatchCb(AuUInt32 read)
    {
        if (AuExchange(this->latch_, true))
        {
            return;
        }
        
        auto memoryHold = this->memoryHold_;
        this->memoryHold_.reset();

        if (this->sub_)
        {
            this->sub_->OnAsyncFileOpFinished(this->lastAbstractOffset_, read);
        }
    }

    void NtAsyncFileTransaction::Reset()
    {
        ::ResetEvent(this->event_);
        this->lastAbstractStat_ = 0; // do not use latch
    }

    bool NtAsyncFileTransaction::Complete()
    {
        DWORD read;

        if (!this->lastAbstractStat_)
        {
            return false;
        }

        if (this->latch_)
        {
            return false;
        }

        if (GetOverlappedResult(this->handle_->handle, &this->overlap_, &read, false))
        {
            bool bLatched = this->latch_;
            DispatchCb(read);
            return !bLatched;
        }

        return false;
    }

    AuUInt32 NtAsyncFileTransaction::GetLastPacketLength()
    {
        DWORD read {};
        GetOverlappedResult(this->handle_->handle, &this->overlap_, &read, false);
        return read;
    }
    
    void NtAsyncFileTransaction::SetCallback(const AuSPtr<IAsyncFinishedSubscriber> &sub)
    {
        this->sub_ = sub;
    }
    
    bool NtAsyncFileTransaction::Wait(AuUInt32 timeout) 
    {
        if (this->latch_)
        {
            return true;
        }

        auto ret = WaitForSingleObjectEx(this->event_, timeout ? timeout : INFINITE, true);
        if (ret == WAIT_OBJECT_0)
        {
            return Complete();
        }
        return false;
    }

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

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

    AuSPtr<Loop::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);
    }
}