/*

 * Copyright (c) 2012 Clément Bœsch

 *

 * 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

 */

/**

 * @file

 * MPlayer subtitles format demuxer

 */

#include "avformat.h"

#include "demux.h"

#include "internal.h"

#include "subtitles.h"

#define TSBASE 10000000

typedef struct {

    FFDemuxSubtitlesQueue q;

} MPSubContext;

static int mpsub_probe(const AVProbeData *p)

{

    const char *ptr     = p->buf;

    const char *ptr_end = p->buf + p->buf_size;

    while (ptr < ptr_end) {

        int inc;

        if (!memcmp(ptr, "FORMAT=TIME", 11))

            return AVPROBE_SCORE_EXTENSION;

        if (!memcmp(ptr, "FORMAT=", 7))

            return AVPROBE_SCORE_EXTENSION / 3;

        inc = ff_subtitles_next_line(ptr);

        if (!inc)

            break;

        ptr += inc;

    }

    return 0;

}

static int parse_line(const char *line, int64_t *value, int64_t *value2)

{

    int vi, p1, p2;

    for (vi = 0; vi < 2; vi++) {

        long long intval, fracval;

        int n = av_sscanf(line, "%lld%n.%lld%n", &intval, &p1, &fracval, &p2);

        if (n <= 0 || intval < INT64_MIN / TSBASE || intval > INT64_MAX / TSBASE)

            return AVERROR_INVALIDDATA;

        intval *= TSBASE;

        if (n == 2) {

            if (fracval < 0)

                return AVERROR_INVALIDDATA;

            for (;p2 - p1 < 7 + 1; p1--)

                fracval *= 10;

            for (;p2 - p1 > 7 + 1; p1++)

                fracval /= 10;

            if (intval > 0) intval = av_sat_add64(intval, fracval);

            else            intval = av_sat_sub64(intval, fracval);

            line += p2;

        } else

            line += p1;

        *value = intval;

        value = value2;

    }

    return 0;

}

static int mpsub_read_header(AVFormatContext *s)

{

    MPSubContext *mpsub = s->priv_data;

    AVStream *st;

    AVBPrint buf;

    AVRational pts_info = (AVRational){ TSBASE, 1 }; // ts based by default

    int res = 0;

    int64_t current_pts = 0;

    int i;

    int common_factor = 0;

    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);

    while (!avio_feof(s->pb)) {

        char line[1024];

        int64_t start, duration;

        int fps, len = ff_get_line(s->pb, line, sizeof(line));

        if (!len)

            break;

        line[strcspn(line, "\r\n")] = 0;

        if (sscanf(line, "FORMAT=%d", &fps) == 1 && fps > 3 && fps < 100) {

            /* frame based timing */

            pts_info = (AVRational){ TSBASE * fps, 1 };

        } else if (parse_line(line, &start, &duration) >= 0) {

            AVPacket *sub;

            const int64_t pos = avio_tell(s->pb);

            res = ff_subtitles_read_chunk(s->pb, &buf);

            if (res < 0) goto end;

            if (buf.len) {

                sub = ff_subtitles_queue_insert_bprint(&mpsub->q, &buf, 0);

                if (!sub) {

                    res = AVERROR(ENOMEM);

                    goto end;

                }

                if (   current_pts < 0 && start < INT64_MIN - current_pts

                    || current_pts > 0 && start > INT64_MAX - current_pts) {

                    res = AVERROR_INVALIDDATA;

                    goto end;

                }

                sub->pts = current_pts + start;

                if (duration < 0 || sub->pts > INT64_MAX - duration) {

                    res = AVERROR_INVALIDDATA;

                    goto end;

                }

                sub->duration = duration;

                common_factor = av_gcd(duration, common_factor);

                common_factor = av_gcd(sub->pts, common_factor);

                current_pts = sub->pts + duration;

                sub->pos = pos;

            }

        }

    }

    if (common_factor > 1) {

        common_factor = av_gcd(pts_info.num, common_factor);

        for (i = 0; i < mpsub->q.nb_subs; i++) {

            mpsub->q.subs[i]->pts      /= common_factor;

            mpsub->q.subs[i]->duration /= common_factor;

        }

        pts_info.num /= common_factor;

    }

    st = avformat_new_stream(s, NULL);

    if (!st) {

        res = AVERROR(ENOMEM);

        goto end;

    }

    avpriv_set_pts_info(st, 64, pts_info.den, pts_info.num);

    st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;

    st->codecpar->codec_id   = AV_CODEC_ID_TEXT;

    ff_subtitles_queue_finalize(s, &mpsub->q);

end:

    av_bprint_finalize(&buf, NULL);

    return res;

}

const FFInputFormat ff_mpsub_demuxer = {

    .p.name         = "mpsub",

    .p.long_name    = NULL_IF_CONFIG_SMALL("MPlayer subtitles"),

    .p.extensions   = "sub",

    .priv_data_size = sizeof(MPSubContext),

    .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,

    .read_probe     = mpsub_probe,

    .read_header    = mpsub_read_header,

    .read_packet    = ff_subtitles_read_packet,

    .read_seek2     = ff_subtitles_read_seek,

    .read_close     = ff_subtitles_read_close,

};