AuroraRuntime/Include/Aurora/IO/Buffered/ViewSeekableReader.hpp

/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: ViewSeekableReader.hpp
    Date: 2022-12-11
    Author: Reece
***/
#pragma once

namespace Aurora::IO::Buffered
{
    struct ViewSeekableReader : ISeekingReader
    {
        AU_NO_COPY(ViewSeekableReader)
        AU_MOVE(ViewSeekableReader)

        inline ViewSeekableReader(const AuSPtr<Memory::MemoryViewRead> &pView) : view_(pView ? *pView.get() : Memory::MemoryViewRead {}), pHold(pView)
        { }

        inline ViewSeekableReader(const Memory::MemoryViewRead &view, AuSPtr<void> pBlock) : view_(view), pHold(pBlock)
        { }

        inline ViewSeekableReader()
        { }

        inline ~ViewSeekableReader()
        { }

        inline virtual EStreamError IsOpen() override
        {
            if (!this->view_)
            {
                return EStreamError::eErrorStreamNotOpen;
            }

            if (!this->pHold)
            {
                return EStreamError::eErrorStreamNotOpen;
            }

            return EStreamError::eErrorNone;
        }

        inline virtual EStreamError ArbitraryRead(AuUInt uOffset, const Memory::MemoryViewStreamWrite &parameters) override
        {
            if (!this->view_)
            {
                return EStreamError::eErrorStreamNotOpen;
            }

            if (!this->pHold)
            {
                return EStreamError::eErrorStreamNotOpen;
            }

            auto iOffset = this->iBaseOffset + AuInt64(uOffset);
            if (iOffset < 0)
            {
                return EStreamError::eErrorOutOfBounds;
            }
            else
            {
                uOffset = iOffset;
            }

            if (this->view_.length < uOffset)
            {
                return EStreamError::eErrorEndOfStream;
            }

            auto uToRead = AuMin(this->view_.length - uOffset, parameters.length);
            parameters.outVariable = uToRead;
            AuMemcpy(parameters.ptr, this->view_.Begin<AuUInt8>() + uOffset, uToRead);
            return parameters.outVariable == 0 ? EStreamError::eErrorEndOfStream : EStreamError::eErrorNone;
        }

        inline virtual void Close() override
        {
            AuResetMember(this->pHold);
            AuResetMember(this->view_);
        }

        inline AuInt64 &GetBaseOffset()
        {
            return this->iBaseOffset;
        }

        inline const AuInt64 &GetBaseOffset() const
        {
            return this->iBaseOffset;
        }

    private:
        Memory::MemoryViewRead view_;
        AuSPtr<void> pHold;
        AuInt64 iBaseOffset {};
    };
}