/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: Compression.cpp
    Date: 2021-6-17
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "Compression.hpp"

#include "zstd.h"

namespace Aurora::Compression
{
    AUKN_SYM bool Compress(const Memory::MemoryViewRead &source, Memory::ByteBuffer &out, int uCompressionLevel)
    {
        if (!out.GetOrAllocateLinearWriteable(source.length))
        {
            SysPushErrorMemory();
            return {};
        }

        auto ret = ZSTD_compress(out.writePtr, source.length, source.ptr, source.length, uCompressionLevel);
        if (ZSTD_isError(ret))
        {
            return false;
        }

        out.writePtr += ret;

        if (!out.flagCircular &&
            out.flagExpandable)
        {
            if (!AuTryDownsize(out, out.writePtr - out.base))
            {
                SysPushErrorMemory();
                return false;
            }
        }

        return true;
    }
    
    AUKN_SYM bool Decompress(const Memory::MemoryViewRead &source, AuByteBuffer &out)
    {
        AuUInt32 read = 0;

        while (read != source.length)
        {
            auto startPtr = reinterpret_cast<const AuUInt8 *>(source.ptr) + read;
            auto deflatedLength = ZSTD_findFrameCompressedSize(startPtr, source.length - read);
            auto inflatedLength = ZSTD_getFrameContentSize(startPtr, source.length - read);

            if (inflatedLength == ZSTD_CONTENTSIZE_ERROR)
            {
                return false;
            }

            if (inflatedLength == ZSTD_CONTENTSIZE_UNKNOWN)
            {
                return false;
            }

            if (ZSTD_isError(inflatedLength))
            {
                return false;
            }
            
            auto view = out.GetOrAllocateLinearWriteable(inflatedLength);
            if (!view)
            {
                SysPushErrorMemory();
                return false;
            }

            auto ret = ZSTD_decompress(view.ptr, inflatedLength, source.ptr, source.length);
            if (ZSTD_isError(ret))
            {
                return false;
            }

            out.writePtr = (AuUInt8 *)view.ptr + ret;

            read += AuUInt32(deflatedLength);
        }

        return true;
    }
}