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

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

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

namespace Aurora::IO::Buffered
{
    struct ViewReader : IStreamReader
    {
        AU_NO_COPY(ViewReader)

        inline ViewReader(const AuSPtr<Memory::MemoryViewRead> &view) : pView_(view)
        { }

        inline ViewReader()
        { }

        inline ~ViewReader()
        { }

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

            if (!(*this->pView_.get()))
            {
                return EStreamError::eErrorStreamNotOpen;
            }

            return EStreamError::eErrorNone;
        }

        inline virtual EStreamError Read(const Memory::MemoryViewStreamWrite &parameters) override
        {
            parameters.outVariable = 0;

            if (!this->pView_)
            {
                return EStreamError::eErrorStreamNotOpen;
            }
            
            if (!(*this->pView_.get()))
            {
                this->pView_.reset();
                return this->uOffset_ ? EStreamError::eErrorStreamNotOpen : EStreamError::eErrorNone;
            }

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

        inline virtual void Close() override
        {
            this->pView_.reset();
        }

        inline AuUInt &GetOffset()
        {
            return this->uOffset_;
        }

        inline const AuUInt &GetOffset() const
        {
            return this->uOffset_;
        }
    private:
        AuSPtr<Memory::MemoryViewRead> pView_;
        AuUInt uOffset_ {};
    };
}