/*****************************************************************************

 * ttmlpes.c : TTML subtitles in EN 303 560 payload

 *****************************************************************************

 * Copyright (C) 2018 VideoLabs, VLC authors and VideoLAN

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation; either version 2.1 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 * GNU Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.

 *****************************************************************************/

#include <vlc_common.h>

#include <vlc_block.h>

#include <vlc_stream.h>

enum

{

    TTML_UNCOMPRESSED_DOCUMENT = 0x01,

    TTML_GZIP_COMPRESSED_DOCUMENT = 0x02,

};

struct ttml_in_pes_ctx

{

    vlc_tick_t i_offset; /* relative segment offset to apply */

    vlc_tick_t i_prev_block_time; /* because blocks are duplicated */

    vlc_tick_t i_prev_segment_start_time; /* because content can overlap */

};

static void ttml_in_pes_Init(struct ttml_in_pes_ctx *p)

{

    p->i_offset = 0;

    p->i_prev_block_time = -1;

    p->i_prev_segment_start_time = -1;

}

static inline bool TTML_in_PES(decoder_t *p_dec)

{

    return p_dec->fmt_in->i_codec == VLC_CODEC_TTML_TS;

}

static block_t * DecompressTTML( decoder_t *p_dec, const uint8_t *p_data, size_t i_data )

{

    block_t *p_decomp = NULL;

    block_t **pp_append = &p_decomp;

    stream_t *s = vlc_stream_MemoryNew( p_dec, (uint8_t *) p_data, i_data, true );

    if( !s )

        return NULL;

    stream_t *p_inflate = vlc_stream_FilterNew( s, "inflate" );

    if( p_inflate )

    {

        for( ;; )

        {

            *pp_append = vlc_stream_Block( p_inflate, 64 * 1024 );

            if( *pp_append == NULL ||

                (*pp_append)->i_buffer < 64*1024 )

                break;

            pp_append = &((*pp_append)->p_next);

        }

        s = p_inflate;

    }

    vlc_stream_Delete( s );

    return p_decomp ? block_ChainGather( p_decomp ) : NULL;

}

static int ParsePESEncap( decoder_t *p_dec,

                          struct ttml_in_pes_ctx *p_ctx,

                          int(*pf_decode)(decoder_t *, block_t *),

                          block_t *p_block )

{

    if( p_block == NULL ) /* No Drain */

        return VLCDEC_SUCCESS;

    if( p_block->i_buffer < 7 )

    {

        block_Release( p_block );

        return VLC_EGENERIC;

    }

    if( p_block->i_dts == p_ctx->i_prev_block_time )

    {

        block_Release( p_block );

        return VLC_SUCCESS;

    }

    int64_t i_segment_base = GetDWBE(p_block->p_buffer);

    i_segment_base = (i_segment_base << 16) | GetWBE(&p_block->p_buffer[4]);

    i_segment_base *= 100;

    uint8_t i_num_segments = p_block->p_buffer[6];

    size_t i_data = p_block->i_buffer - 7;

    const uint8_t *p_data = &p_block->p_buffer[7];

    p_ctx->i_offset = (p_block->i_dts - VLC_TICK_0) - i_segment_base;

    for( uint8_t i=0; i<i_num_segments; i++ )

    {

        if( i_data < 3 )

            break;

        uint8_t i_type = p_data[0];

        uint16_t i_size = GetWBE(&p_data[1]);

        if( i_size > i_data - 3 )

            break;

        block_t *p_segment = NULL;

        if( i_type == TTML_UNCOMPRESSED_DOCUMENT )

        {

            p_segment = block_Alloc( i_size );

            if( p_segment )

                memcpy( p_segment->p_buffer, &p_data[3], i_size );

        }

        else if( i_type == TTML_GZIP_COMPRESSED_DOCUMENT )

        {

            p_segment = DecompressTTML( p_dec, &p_data[3], i_size );

        }

        if( p_segment )

        {

            block_CopyProperties( p_segment, p_block );

            pf_decode( p_dec, p_segment );

        }

        p_data += 3 + i_size;

        i_data -= 3 + i_size;

    }

    p_ctx->i_prev_block_time = p_block->i_dts;

    block_Release( p_block );

    return VLC_SUCCESS;

}