/**************************************************************
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * 
 *************************************************************/


#include "oox/ole/vbainputstream.hxx"
#include <osl/diagnose.h>

namespace oox {
namespace ole {

// ============================================================================

namespace {

const sal_uInt8 VBASTREAM_SIGNATURE         = 1;

const sal_uInt16 VBACHUNK_SIGMASK           = 0x7000;
const sal_uInt16 VBACHUNK_SIG               = 0x3000;
const sal_uInt16 VBACHUNK_COMPRESSED        = 0x8000;
const sal_uInt16 VBACHUNK_LENMASK           = 0x0FFF;

} // namespace

// ============================================================================

VbaInputStream::VbaInputStream( BinaryInputStream& rInStrm ) :
    BinaryStreamBase( false ),
    mpInStrm( &rInStrm ),
    mnChunkPos( 0 )
{
    maChunk.reserve( 4096 );

    sal_uInt8 nSig = rInStrm.readuInt8();
    OSL_ENSURE( nSig == VBASTREAM_SIGNATURE, "VbaInputStream::VbaInputStream - wrong signature" );
    mbEof = mbEof || rInStrm.isEof() || (nSig != VBASTREAM_SIGNATURE);
}

sal_Int64 VbaInputStream::size() const
{
    return -1;
}

sal_Int64 VbaInputStream::tell() const
{
    return -1;
}

void VbaInputStream::seek( sal_Int64 )
{
}

void VbaInputStream::close()
{
    mpInStrm = 0;
    mbEof = true;
}

sal_Int32 VbaInputStream::readData( StreamDataSequence& orData, sal_Int32 nBytes, size_t nAtomSize )
{
    sal_Int32 nRet = 0;
    if( !mbEof )
    {
        orData.realloc( ::std::max< sal_Int32 >( nBytes, 0 ) );
        if( nBytes > 0 )
        {
            nRet = readMemory( orData.getArray(), nBytes, nAtomSize );
            if( nRet < nBytes )
                orData.realloc( nRet );
        }
    }
    return nRet;
}

sal_Int32 VbaInputStream::readMemory( void* opMem, sal_Int32 nBytes, size_t /*nAtomSize*/ )
{
    sal_Int32 nRet = 0;
    sal_uInt8* opnMem = reinterpret_cast< sal_uInt8* >( opMem );
    while( (nBytes > 0) && updateChunk() )
    {
        sal_Int32 nChunkLeft = static_cast< sal_Int32 >( maChunk.size() - mnChunkPos );
        sal_Int32 nReadBytes = ::std::min( nBytes, nChunkLeft );
        memcpy( opnMem, &*(maChunk.begin() + mnChunkPos), nReadBytes );
        opnMem += nReadBytes;
        mnChunkPos += static_cast< size_t >( nReadBytes );
        nBytes -= nReadBytes;
        nRet += nReadBytes;
    }
    return nRet;
}

void VbaInputStream::skip( sal_Int32 nBytes, size_t /*nAtomSize*/ )
{
    while( (nBytes > 0) && updateChunk() )
    {
        sal_Int32 nChunkLeft = static_cast< sal_Int32 >( maChunk.size() - mnChunkPos );
        sal_Int32 nSkipBytes = ::std::min( nBytes, nChunkLeft );
        mnChunkPos += static_cast< size_t >( nSkipBytes );
        nBytes -= nSkipBytes;
    }
}

// private --------------------------------------------------------------------

bool VbaInputStream::updateChunk()
{
    if( mbEof || (mnChunkPos < maChunk.size()) ) return !mbEof;

    // try to read next chunk header, this may trigger EOF
    sal_uInt16 nHeader = mpInStrm->readuInt16();
    mbEof = mpInStrm->isEof();
    if( mbEof ) return false;

    // check header signature
    OSL_ENSURE( (nHeader & VBACHUNK_SIGMASK) == VBACHUNK_SIG, "VbaInputStream::updateChunk - invalid chunk signature" );
    mbEof = (nHeader & VBACHUNK_SIGMASK) != VBACHUNK_SIG;
    if( mbEof ) return false;

    // decode length of chunk data and compression flag
    bool bCompressed = getFlag( nHeader, VBACHUNK_COMPRESSED );
    sal_uInt16 nChunkLen = (nHeader & VBACHUNK_LENMASK) + 1;
    OSL_ENSURE( bCompressed || (nChunkLen == 4096), "VbaInputStream::updateChunk - invalid uncompressed chunk size" );
    if( bCompressed )
    {
        maChunk.clear();
        sal_uInt8 nBitCount = 4;
        sal_uInt16 nChunkPos = 0;
        while( !mbEof && !mpInStrm->isEof() && (nChunkPos < nChunkLen) )
        {
            sal_uInt8 nTokenFlags = mpInStrm->readuInt8();
            ++nChunkPos;
            for( int nBit = 0; !mbEof && !mpInStrm->isEof() && (nBit < 8) && (nChunkPos < nChunkLen); ++nBit, nTokenFlags >>= 1 )
            {
                if( nTokenFlags & 1 )
                {
                    sal_uInt16 nCopyToken = mpInStrm->readuInt16();
                    nChunkPos = nChunkPos + 2;
                    // update bit count used for offset/length in the token
                    while( static_cast< size_t >( 1 << nBitCount ) < maChunk.size() ) ++nBitCount;
                    // extract length from lower (16-nBitCount) bits, plus 3
                    sal_uInt16 nLength = extractValue< sal_uInt16 >( nCopyToken, 0, 16 - nBitCount ) + 3;
                    // extract offset from high nBitCount bits, plus 1
                    sal_uInt16 nOffset = extractValue< sal_uInt16 >( nCopyToken, 16 - nBitCount, nBitCount ) + 1;
                    mbEof = (nOffset > maChunk.size()) || (maChunk.size() + nLength > 4096);
                    OSL_ENSURE( !mbEof, "VbaInputStream::updateChunk - invalid offset or size in copy token" );
                    if( !mbEof )
                    {
                        // append data to buffer
                        maChunk.resize( maChunk.size() + nLength );
                        sal_uInt8* pnTo = &*(maChunk.end() - nLength);
                        const sal_uInt8* pnEnd = pnTo + nLength;
                        const sal_uInt8* pnFrom = pnTo - nOffset;
                        // offset may be less than length, effectively duplicating source data several times
                        size_t nRunLen = ::std::min< size_t >( nLength, nOffset );
                        while( pnTo < pnEnd )
                        {
                            size_t nStepLen = ::std::min< size_t >( nRunLen, pnEnd - pnTo );
                            memcpy( pnTo, pnFrom, nStepLen );
                            pnTo += nStepLen;
                        }
                    }
                }
                else
                {
                    maChunk.resize( maChunk.size() + 1 );
                    *mpInStrm >> maChunk.back();
                    ++nChunkPos;
                }
            }
        }
    }
    else
    {
        maChunk.resize( nChunkLen );
        mpInStrm->readMemory( &maChunk.front(), nChunkLen );
    }

    mnChunkPos = 0;
    return !mbEof;
}

// ============================================================================

} // namespace ole
} // namespace oox