/*     Copyright 2015-2019 Egor Yusov
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF ANY PROPRIETARY RIGHTS.
 *
 *  In no event and under no legal theory, whether in tort (including negligence), 
 *  contract, or otherwise, unless required by applicable law (such as deliberate 
 *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
 *  liable for any damages, including any direct, indirect, special, incidental, 
 *  or consequential damages of any character arising as a result of this License or 
 *  out of the use or inability to use the software (including but not limited to damages 
 *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
 *  all other commercial damages or losses), even if such Contributor has been advised 
 *  of the possibility of such damages.
 */

#include <algorithm>
#include "pch.h"

#include "MemoryFileStream.h"

namespace Diligent
{
    MemoryFileStream::MemoryFileStream(IReferenceCounters* pRefCounters,
                                       IDataBlob*          pData) :
        TBase(pRefCounters),
        m_DataBlob(pData)
    {
    }

    IMPLEMENT_QUERY_INTERFACE(MemoryFileStream, IID_FileStream, TBase)

    bool MemoryFileStream::Read(void* Data, size_t Size)
    {
        VERIFY_EXPR(m_CurrentOffset <= m_DataBlob->GetSize());
        auto BytesLeft = m_DataBlob->GetSize() - m_CurrentOffset;
        auto BytesToRead = std::min(BytesLeft, Size);
        auto* pSrcData = reinterpret_cast<const Uint8*>(m_DataBlob->GetDataPtr()) + m_CurrentOffset;
        memcpy(Data, pSrcData, BytesToRead);
        m_CurrentOffset += BytesToRead;
        return Size == BytesToRead;
    }

    void MemoryFileStream::Read( IDataBlob* pData )
    {
        auto BytesLeft = m_DataBlob->GetSize() - m_CurrentOffset;
        pData->Resize(BytesLeft);
        auto res = Read(pData->GetDataPtr(), pData->GetSize());
        VERIFY_EXPR(res); (void)res;
    }

    bool MemoryFileStream::Write(const void* Data, size_t Size)
    {
        if (m_CurrentOffset + Size > m_DataBlob->GetSize())
        {
            m_DataBlob->Resize(m_CurrentOffset + Size);
        }
        auto* DstData = reinterpret_cast<Uint8*>(m_DataBlob->GetDataPtr()) + m_CurrentOffset;
        memcpy(DstData, Data, Size);
        m_CurrentOffset += Size;
        return true;
    }

    bool MemoryFileStream::IsValid()
    {
        return !!m_DataBlob;
    }

    size_t MemoryFileStream::GetSize()
    {
        return m_DataBlob->GetSize();
    }
}
