// code to convert little inferno sound resources to ogg files
// the version of libogg that you use here must be version 1.1.4
// dec 12, 2012 - allan blomquist

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>

// MUST use libogg-1.1.4 - not any other version!
#include <ogg/ogg.h>

struct SoundHeader
{
    int totalSampleCountPerChannel;
    int oggTotalDataSizeBytes;
    int vorbisMarkersSizeBytes;
    int vorbisWorkingSetSizeBytes;
    int vorbisPacketsSizeBytes;
    int samplesPerSec;
    int channels;
};

struct StreamMarker
{
    int packetStreamByteOffset;
    int pcmSampleOffset;
    int packetIdx;
};

int main( int argc, const char *argv[] )
{
    FILE *fSrc = fopen( argv[1], "rb" );
    FILE *fDest = fopen( "out.ogg", "wb" );

    // read header
    SoundHeader hdr;
    fread( &hdr, 1, sizeof(hdr), fSrc );

    // read stream markers
    int numMarkers = hdr.vorbisMarkersSizeBytes / sizeof(StreamMarker);
    StreamMarker *pMarkers = new StreamMarker[ numMarkers ];
    fread( pMarkers, sizeof(StreamMarker), numMarkers, fSrc );

    // setup for making an ogg stream - serial number isn't going to matter
    ogg_stream_state os;
    const int kOggStreamSerialNo = 0x00001234;
    ogg_stream_init( &os, kOggStreamSerialNo );

    int doneBytes = 0;
    int donePackets = 0;

    // always skip the first marker
    int doneMarkers = 1;

    // convert raw vorbis packets to ogg stream
    while( doneBytes < hdr.vorbisPacketsSizeBytes )
    {
        // packet size comes first
        short packetSizeBytes;
        fread( &packetSizeBytes, 1, sizeof(packetSizeBytes), fSrc );

        // followed by packet data
        unsigned char *pPacketData = new unsigned char[ packetSizeBytes ];
        fread( pPacketData, 1, packetSizeBytes, fSrc );

        // set up an ogg packet with the data we just read
        ogg_packet op;
        op.packet = pPacketData;
        op.bytes = packetSizeBytes;

        // granule pos mostly maps 1:1 with markers but there are a few special cases for the first few packets
        if( (donePackets == 0) || (donePackets == 2) )
        {
            op.granulepos = 0;
        }
        else
        {
            op.granulepos = -1;

            StreamMarker *pNextMarker = pMarkers + doneMarkers;
            if( (donePackets >= 4) && (pNextMarker->packetStreamByteOffset == doneBytes) )
            {
                op.granulepos = pNextMarker->pcmSampleOffset;
                ++doneMarkers;
            }
        }

        int packetStreamAdvanceBytes = sizeof(packetSizeBytes) + packetSizeBytes;
        bool lastPacket = (doneBytes + packetStreamAdvanceBytes) >= hdr.vorbisPacketsSizeBytes;

        // these flag values are what come out of libogg when decoding the original files
        op.b_o_s = (donePackets == 0) ? 256 : 0;
        op.e_o_s = (lastPacket) ? 512 : 0;

        op.packetno = donePackets;

        // give packet to ogg stream
        ogg_stream_packetin( &os, &op );
        delete [] pPacketData;

        doneBytes += packetStreamAdvanceBytes;
        ++donePackets;

        // flush ogg stream after first 3 packets (as required by spec) and at end of stream
        if( (donePackets == 3) || lastPacket )
        {
            while( true )
            {
                ogg_page og;
                int result = ogg_stream_flush( &os, &og );
                if( result == 0 ) break;
                fwrite( og.header, 1, og.header_len, fDest );
                fwrite( og.body, 1, og.body_len, fDest );
            }
        }
    }

    // cleanup
    ogg_stream_clear(&os);

    delete [] pMarkers;

    fclose( fDest );
    fclose( fSrc );

    return 0;
}