/*
 * Copyright (C) 2007-2023 Xagasoft, All rights reserved.
 *
 * This file is part of the libbu++ library and is released under the
 * terms of the license contained in the file LICENSE.
 */

#include "bu/substream.h"

Bu::SubStream::SubStream( Bu::Stream &rNext, Bu::size iSize ) :
    Bu::Filter( rNext ),
    iStart( 0 ),
    iPos( 0 ),
    iSize( iSize )
{
    iStart = rNext.tell();
}

Bu::SubStream::~SubStream()
{
}

Bu::size Bu::SubStream::read( void *pBuf, Bu::size nBytes )
{
    if( (Bu::size)nBytes > iSize-iPos )
        nBytes = iSize-iPos;
    nBytes = rNext.read( pBuf, nBytes );
    iPos += nBytes;
    return nBytes;
}

Bu::size Bu::SubStream::write( const void *pBuf, Bu::size nBytes )
{
    if( (Bu::size)nBytes > iSize-iPos )
        nBytes = iSize-iPos;
    nBytes = rNext.write( pBuf, nBytes );
    iPos += nBytes;
    return nBytes;
}

void Bu::SubStream::start()
{
    // doesn't mean anything...
}

Bu::size Bu::SubStream::stop()
{
    // doesn't mean anything...
    return 0;
}

void Bu::SubStream::close()
{
    // don't do anything?  maybe...
}

Bu::size Bu::SubStream::tell()
{
    return iPos;
}

void Bu::SubStream::seek( Bu::size offset )
{
    if( iPos+offset < 0 )
        offset = -iPos;
    else if( iPos+offset > iSize )
        offset = iSize-iPos;
    rNext.seek( offset );
    iPos += offset;
}

void Bu::SubStream::setPos( Bu::size pos )
{
    if( pos < 0 )
        pos = 0;
    else if( pos > iSize )
        pos = iSize;
    iPos = pos;
    pos += iStart;
    rNext.setPos( pos );
}

void Bu::SubStream::setPosEnd( Bu::size pos )
{
    if( iSize-pos < 0 )
        pos = 0;
    else if( iSize-pos > iSize )
        pos = iSize;
    else
        pos = iSize-pos;
    iPos = pos;
    rNext.setPos( iStart+pos );
}

bool Bu::SubStream::isEos()
{
    return rNext.isEos() || iPos == iSize;
}

bool Bu::SubStream::canRead()
{
    return rNext.canRead() && (iPos < iSize);
}

bool Bu::SubStream::canWrite()
{
    return rNext.canWrite() && (iPos < iSize);
}

