/*

 * SCC subtitle demuxer

 * Copyright (c) 2017 Paul B Mahol

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg 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.

 *

 * FFmpeg 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 FFmpeg; if not, write to the Free Software

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

 */

#include "avformat.h"

#include "demux.h"

#include "internal.h"

#include "subtitles.h"

#include "libavutil/avstring.h"

#include "libavutil/intreadwrite.h"

typedef struct SCCContext {

    FFDemuxSubtitlesQueue q;

} SCCContext;

static int scc_probe(const AVProbeData *p)

{

    char buf[18];

    FFTextReader tr;

    ff_text_init_buf(&tr, p->buf, p->buf_size);

    while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n')

        ff_text_r8(&tr);

    ff_text_read(&tr, buf, sizeof(buf));

    if (!memcmp(buf, "Scenarist_SCC V1.0", 18))

        return AVPROBE_SCORE_MAX;

    return 0;

}

static int convert(uint8_t x)

{

    if (x >= 'a')

        x -= 'a' - 10;

    else if (x >= 'A')

        x -= 'A' - 10;

    else

        x -= '0';

    return x;

}

static int scc_read_header(AVFormatContext *s)

{

    SCCContext *scc = s->priv_data;

    AVStream *st = avformat_new_stream(s, NULL);

    AVPacket *sub = NULL;

    ptrdiff_t len;

    uint8_t out[4096];

    FFTextReader tr;

    ff_text_init_avio(s, &tr, s->pb);

    if (!st)

        return AVERROR(ENOMEM);

    avpriv_set_pts_info(st, 64, 1, 1000);

    st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;

    st->codecpar->codec_id   = AV_CODEC_ID_EIA_608;

    while (1) {

        char *saveptr = NULL, *lline;

        int hh, mm, ss, fs, i;

        char line[4096];

        int64_t pos, ts;

        pos = ff_text_pos(&tr);

        len = ff_subtitles_read_line(&tr, line, sizeof(line));

        if (len <= 13) {

            if (ff_text_eof(&tr))

                break;

            continue;

        }

        if (av_sscanf(line, "%d:%d:%d%*[:;]%d", &hh, &mm, &ss, &fs) != 4)

            continue;

        ts = (hh * 3600LL + mm * 60LL + ss) * 1000LL + fs * 33LL;

        if (sub)

            sub->duration = ts - sub->pts;

        lline  = line;

        lline += 12;

        for (i = 0; i < 4095; i += 3) {

            char *ptr = av_strtok(lline, " ", &saveptr);

            char c1, c2, c3, c4;

            uint8_t o1, o2;

            if (!ptr)

                break;

            if (av_sscanf(ptr, "%c%c%c%c", &c1, &c2, &c3, &c4) != 4)

                break;

            o1 = convert(c2) | (convert(c1) << 4);

            o2 = convert(c4) | (convert(c3) << 4);

            lline = NULL;

            if (i > 12 && o1 == 0x94 && o2 == 0x20 && saveptr &&

                (av_strncasecmp(saveptr, "942f", 4) && !av_strncasecmp(saveptr, "942c", 4))) {

                sub = ff_subtitles_queue_insert(&scc->q, out, i, 0);

                if (!sub)

                    return AVERROR(ENOMEM);

                sub->pos = pos;

                pos += i;

                sub->pts = ts;

                sub->duration = i * 11;

                ts += sub->duration;

                i = 0;

            }

            out[i+0] = 0xfc;

            out[i+1] = o1;

            out[i+2] = o2;

        }

        sub = ff_subtitles_queue_insert(&scc->q, out, i, 0);

        if (!sub)

            return AVERROR(ENOMEM);

        sub->pos = pos;

        sub->pts = ts;

    }

    ff_subtitles_queue_finalize(s, &scc->q);

    return 0;

}

const FFInputFormat ff_scc_demuxer = {

    .p.name         = "scc",

    .p.long_name    = NULL_IF_CONFIG_SMALL("Scenarist Closed Captions"),

    .p.extensions   = "scc",

    .priv_data_size = sizeof(SCCContext),

    .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,

    .read_probe     = scc_probe,

    .read_header    = scc_read_header,

    .read_packet    = ff_subtitles_read_packet,

    .read_seek2     = ff_subtitles_read_seek,

    .read_close     = ff_subtitles_read_close,

};