/***
    Copyright (C) 2024 Jamie Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: FSMemoryMappedFile.cpp
    Date: 2024-03-05
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "FSMemoryMappedFile.hpp"
#include <Source/IO/Adapters/AuIOAdapterAsyncDelegators.hpp>

namespace Aurora::IO::FS
{
    IIOHandle *               MemoryMappedFile::ToHandle()
    { 
        return this->pHandleShared ?
            this->pHandleShared.get() :
            this->handle.AsPointer();
    }

    AuUInt                     MemoryMappedFile::GetBaseAddress()
    {
        if (this->pView)
        {
            return (AuUInt)this->pView->GetBasePointer();
        }
        else
        {
            return 0;
        }
    }

    AuUInt                     MemoryMappedFile::GetEndAddress()
    {
        if (this->pView)
        {
            return (AuUInt)this->pView->GetBasePointer() +
                this->GetLength();
        }
        else
        {
            return 0;
        }
    }

    AuUInt                     MemoryMappedFile::GetLength()
    { 
        return this->uFileMapLength;
    }

    AuSPtr<IStreamReader>      MemoryMappedFile::NewStreamReader()
    { 
        return AuMakeShared<IO::Buffered::ViewReader>(this->ToReadView(), this->pView);
    }

    AuSPtr<IStreamWriter>      MemoryMappedFile::NewStreamWriter()
    {
        return AuMakeShared<IO::Buffered::ViewWriter>(this->ToWriteView(), this->pView);
    }

    void MemoryMappedFile::InitTransactions()
    {
        if (AuThreading::InitOnceLocker::TryLock(&this->initOnce))
        {
            bool bOk { true };

            if (this->eMode == EFileOpenMode::eReadWrite ||
                this->eMode == EFileOpenMode::eRead)
            {
                auto pReader = AuMakeShared<IO::Buffered::ViewSeekableReader>(this->ToReadViewAlt(), this->pView);

                if (pReader)
                {
                    auto iBaseOffset = 0 -
                        AuInt64(this->uFileMapOffset) +
                        this->iAdjustStreamOffset;

                    pReader->GetBaseOffset() = iBaseOffset;
                }
                else
                {
                    bOk = false;
                }

                this->pStreamReader = pReader;
            }

            if (this->eMode == EFileOpenMode::eReadWrite ||
                this->eMode == EFileOpenMode::eWrite)
            {
                auto pWriter = AuMakeShared<IO::Buffered::ViewSeekableWriter>(this->ToWriteViewAlt(), this->pView);

                if (pWriter)
                {
                    auto iBaseOffset = 0 -
                        AuInt64(this->uFileMapOffset) +
                        this->iAdjustStreamOffset;

                    pWriter->GetBaseOffset() = iBaseOffset;
                }
                else
                {
                    bOk = false;
                }

                this->pStreamWriter = pWriter;
            }
            AuThreading::InitOnceLocker::Finish(&this->initOnce, !bOk);
        }
        else
        {
            this->initOnce.Wait();
        }
    }

    AuSPtr<IAsyncTransaction>  MemoryMappedFile::NewAsyncReadTransaction()
    { 
        this->InitTransactions();
        SysCheckNotNullMemory(this->pStreamReader, {});
        auto pTransaction = Adapters::NewAsyncTransactionFromStreamSeekingReader(this->pStreamReader, {});
        SysCheckNotNullMemory(pTransaction, {});
        return pTransaction;
    }

    AuSPtr<IAsyncTransaction>  MemoryMappedFile::NewAsyncWriteTransaction()
    { 
        this->InitTransactions();
        SysCheckNotNullMemory(this->pStreamWriter, {});
        auto pTransaction = Adapters::NewAsyncTransactionFromStreamSeekingWriter(this->pStreamWriter, {});
        SysCheckNotNullMemory(pTransaction, {});
        return pTransaction;
    }

    AuSPtr<IAsyncTransaction>  MemoryMappedFile::NewAsyncAnyTransaction()
    {
        this->InitTransactions();
        SysCheckNotNullMemory(this->pStreamWriter, {});
        SysCheckNotNullMemory(this->pStreamReader, {});
        auto pTransaction = Adapters::NewAsyncTransactionFromStreamSeekingPair(this->pStreamReader, this->pStreamWriter, {});
        SysCheckNotNullMemory(pTransaction, {});
        return pTransaction;
    }

    ISeekingReader *MemoryMappedFile::ToStreamSeekingReader()
    {
        if (this->optSeekableReader)
        {
            return &this->optSeekableReader.Value();
        }
        else
        {
            return nullptr;
        }
    }

    ISeekingWriter *MemoryMappedFile::ToStreamSeekingWriter()
    { 
        if (this->optSeekableWriter)
        {
            return &this->optSeekableWriter.Value();
        }
        else
        {
            return nullptr;
        }
    }

    AuMemoryViewRead MemoryMappedFile::ToReadView()
    {
        auto pBasePointer = this->pView->GetBasePointer();

        auto iBaseOffset = 0 -
            AuInt64(this->uFileMapOffset) +
            this->iAdjustStreamOffset;

        if (iBaseOffset < 0)
        {
            return {};
        }

        auto pHeadPointer = pBasePointer + iBaseOffset;

        return { pHeadPointer, this->GetEndAddress() - AuUInt(pHeadPointer) };
    }

    AuMemoryViewWrite MemoryMappedFile::ToWriteView()
    {
        auto pBasePointer = this->pView->GetBasePointer();

        auto iBaseOffset = 0 -
            AuInt64(this->uFileMapOffset) +
            this->iAdjustStreamOffset;

        if (iBaseOffset < 0)
        {
            return {};
        }

        auto pHeadPointer = pBasePointer + iBaseOffset;

        return { pHeadPointer, this->GetEndAddress() - AuUInt(pHeadPointer) };
    }
    
    AuMemoryViewRead MemoryMappedFile::ToReadViewAlt()
    {
        auto pBasePointer = this->pView->GetBasePointer();
        return { pBasePointer, this->GetEndAddress() - AuUInt(pBasePointer) };
    }

    AuMemoryViewWrite MemoryMappedFile::ToWriteViewAlt()
    {
        auto pBasePointer = this->pView->GetBasePointer();
        return { pBasePointer, this->GetEndAddress() - AuUInt(pBasePointer) };
    }

    void                       MemoryMappedFile::Flush(AuUInt uOffset,
                                                       AuUInt uLength)
    { 
        auto iOffset = 0 - AuSInt(this->uFileMapOffset) + AuSInt(iAdjustStreamOffset) + AuSInt(uOffset);
        if (iOffset < 0)
        {
            return;
        }

        auto uStartAddress = iOffset;
        auto uEndAddress   = AuMin(this->GetLength(), uStartAddress + uLength);
        auto uSecondLength = uEndAddress - uStartAddress;
        this->pView->Flush(iOffset, uSecondLength);
    }

    void                       MemoryMappedFile::Prefetch(AuUInt uOffset,
                                                          AuUInt uLength)
    {
        AU_DEBUG_MEMCRUNCH;

        auto iOffset = 0 - AuSInt(this->uFileMapOffset) + AuSInt(iAdjustStreamOffset) + AuSInt(uOffset);
        if (iOffset < 0)
        {
            return;
        }

        auto uStartAddress = this->GetBaseAddress() + iOffset;
        auto uEndAddress   = AuMin(this->GetEndAddress(), uStartAddress + uLength);
        auto uSecondLength = uEndAddress - uStartAddress;

        AuMemory::Cache::OptimizeAddressRangeOnCore({
            {
                uStartAddress,
                uSecondLength
            }
        });
    }

    IAsyncFileStream *MemoryMappedFile::ToAsyncFile()
    {
        return this;
    }

    AuSPtr<IAsyncTransaction> MemoryMappedFile::NewTransaction()
    {
        return this->NewAsyncAnyTransaction();
    }

    bool MemoryMappedFile::BlockingTruncate(AuUInt64 length)
    {
        return false;
    }
    
    bool MemoryMappedFile::BlockingRead(AuUInt64 offset, const Memory::MemoryViewStreamWrite &parameters)
    {
        this->InitTransactions();
        SysCheckNotNullMemory(this->pStreamReader, {});
        return this->pStreamReader->ArbitraryRead(offset, parameters) == EStreamError::eErrorNone;
    }
    
    bool MemoryMappedFile::BlockingWrite(AuUInt64 offset, const Memory::MemoryViewStreamRead &parameters)
    {
        this->InitTransactions();
        SysCheckNotNullMemory(this->pStreamWriter, {});
        return this->pStreamWriter->ArbitraryWrite(offset, parameters) == EStreamError::eErrorNone;
    }

    bool MemoryMappedFile::Init(EFileOpenMode eMode,
                                AuUInt64  uFileMapOffset,
                                AuUInt64  uFileMapLength,
                                AuInt64   iAdjustStreamOffset,
                                EFileAdvisoryLockLevel eLockLevel)
    {
        auto pHandle = this->ToHandle();

        if (!uFileMapLength)
        {
            uFileMapLength = pHandle->GetFileLength();
        }

        this->eMode = eMode;
        this->uFileMapLength = uFileMapLength;
        this->uFileMapOffset = uFileMapOffset;
        this->iAdjustStreamOffset = iAdjustStreamOffset;

        auto pAddressSpace = AuProcess::GetGlobalProcessSpace();
        
        this->pView = pAddressSpace->MapFileByObject(AuUnsafeRaiiToShared(this->ToHandle()),
                                                     uFileMapOffset,
                                                     uFileMapLength,
                                                     eMode,
                                                     eLockLevel);
        if (!this->pView)
        {
            SysPushErrorNested();
            return false;
        }

        {
            auto iBaseOffset = 0 -
                AuInt64(this->uFileMapOffset) +
                this->iAdjustStreamOffset;

            IO::Buffered::ViewSeekableReader reader(this->ToReadViewAlt(), this->pView);
            IO::Buffered::ViewSeekableWriter writer(this->ToWriteViewAlt(), this->pView);

            writer.GetBaseOffset() = iBaseOffset;
            reader.GetBaseOffset() = iBaseOffset;

            this->optSeekableReader = AuMove(reader);
            this->optSeekableWriter = AuMove(writer);
        }

        return true;
    }

    IMemoryMappedFile *OpenMapNew(const AuString &path,
                                  AuOptional<EFileOpenMode> opteMode,
                                  AuOptional<AuUInt64> optuFileMapOffset,
                                  AuOptional<AuUInt64> optuFileMapLength,
                                  AuOptional<AuInt64>  optiAdjustStreamOffset,
                                  AuOptional<EFileAdvisoryLockLevel> opteAdvisoryLevel,
                                  AuOptional<bool> optbLockEntireFile)
    {
        auto eMode               = opteMode.ValueOr(EFileOpenMode::eRead);
        auto uFileMapOffset      = optuFileMapOffset.ValueOr(0);
        auto uFileLength         = optuFileMapLength.ValueOr(0);
        auto iAdjustStreamOffset = optiAdjustStreamOffset.ValueOr(uFileMapOffset);
        auto bLockEntireFile     = optbLockEntireFile.ValueOr(true);
        auto eAdvisoryLevel      = opteAdvisoryLevel.ValueOr(EFileAdvisoryLockLevel::eBlockReadWrite);

        auto pReturn = _new MemoryMappedFile();
        SysCheckNotNullMemory(pReturn, {});

        auto createRequest = AuIO::IIOHandle::HandleCreate::Create(path);
        createRequest.eMode = eMode;
        createRequest.eAdvisoryLevel = bLockEntireFile ? eAdvisoryLevel : EFileAdvisoryLockLevel::eNoSafety;
        createRequest.bDirectIOMode = false;

        if (!pReturn->handle->InitFromPath(createRequest))
        {
            delete pReturn;
            return nullptr;
        }

        if (!pReturn->Init(eMode, uFileMapOffset, uFileLength, iAdjustStreamOffset, !bLockEntireFile ? eAdvisoryLevel : EFileAdvisoryLockLevel::eNoSafety))
        {
            delete pReturn;
            return nullptr;
        }

        return pReturn;
    }

    void OpenMapRelease(IMemoryMappedFile *pReturn)
    {
        AuSafeDelete<MemoryMappedFile *>(pReturn);
    }

    IMemoryMappedFile *OpenMapFromSharedHandleNew(const AuSPtr<IIOHandle> &pIOHandle,
                                                  AuOptional<AuUInt64> optuFileMapOffset,
                                                  AuOptional<AuUInt64> optuFileMapLength,
                                                  AuOptional<AuInt64>  optiAdjustStreamOffset,
                                                  AuOptional<EFileAdvisoryLockLevel> opteAdvisoryLevel)
    {
        auto uFileMapOffset      = optuFileMapOffset.ValueOr(0);
        auto uFileLength         = optuFileMapLength.ValueOr(0);
        auto iAdjustStreamOffset = optiAdjustStreamOffset.ValueOr(uFileMapOffset);
        auto eAdvisoryLevel      = opteAdvisoryLevel.ValueOr(EFileAdvisoryLockLevel::eNoSafety);

        SysCheckArgNotNull(pIOHandle, {});

        auto pReturn = _new MemoryMappedFile();
        SysCheckNotNullMemory(pReturn, {});

        pReturn->pHandleShared = pIOHandle;

        if (!pReturn->Init(pIOHandle->GetOSWriteHandleSafe() ? EFileOpenMode::eReadWrite : EFileOpenMode::eRead,
                           uFileMapOffset,
                           uFileLength,
                           iAdjustStreamOffset,
                           eAdvisoryLevel))
        {
            delete pReturn;
            return nullptr;
        }

        return pReturn;
    }

    void OpenMapFromSharedHandleRelease(IMemoryMappedFile *pReturn)
    {
        AuSafeDelete<MemoryMappedFile *>(pReturn);
    }
}