/*
  * SubRip subtitle demuxer
  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>

  * Copyright (c) 2015  Clément Bœsch <u pkh me>

  *
  * 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 "internal.h"

 #include "subtitles.h"

 #include "libavutil/bprint.h"

 #include "libavutil/intreadwrite.h"
 

 typedef struct {
     FFDemuxSubtitlesQueue q;
 } SRTContext;
 

 static int srt_probe(AVProbeData *p)
 {

     int v;
     char buf[64], *pbuf;

     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);

 
     /* Check if the first non-empty line is a number. We do not check what the

      * number is because in practice it can be anything.
      * Also, that number can be followed by random garbage, so we can not
      * unfortunately check that we only have a number. */

     if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0 ||

         strtol(buf, &pbuf, 10) < 0 || pbuf == buf)

         return 0;
 
     /* Check if the next line matches a SRT timestamp */
     if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0)
         return 0;

     if (buf[0] >= '0' && buf[0] <= '9' && strstr(buf, " --> ")

         && sscanf(buf, "%*d:%*2d:%*2d%*1[,.]%*3d --> %*d:%*2d:%*2d%*1[,.]%3d", &v) == 1)
         return AVPROBE_SCORE_MAX;
 

     return 0;
 }
 

 struct event_info {
     int32_t x1, x2, y1, y2;
     int duration;
     int64_t pts;
     int64_t pos;
 };
 
 static int get_event_info(const char *line, struct event_info *ei)
 {
     int hh1, mm1, ss1, ms1;
     int hh2, mm2, ss2, ms2;
 
     ei->x1 = ei->x2 = ei->y1 = ei->y2 = ei->duration = -1;
     ei->pts = AV_NOPTS_VALUE;
     ei->pos = -1;
     if (sscanf(line, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
                "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
                &hh1, &mm1, &ss1, &ms1,
                &hh2, &mm2, &ss2, &ms2,
                &ei->x1, &ei->x2, &ei->y1, &ei->y2) >= 8) {
         const int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1;
         const int64_t end   = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2;
         ei->duration = end - start;
         ei->pts = start;
         return 0;
     }
     return -1;
 }
 
 static int add_event(FFDemuxSubtitlesQueue *q, AVBPrint *buf, char *line_cache,
                      const struct event_info *ei, int append_cache)

 {

     if (append_cache && line_cache[0])
         av_bprintf(buf, "%s\n", line_cache);
     line_cache[0] = 0;
 
     while (buf->len > 0 && buf->str[buf->len - 1] == '\n')
         buf->str[--buf->len] = 0;
 
     if (buf->len) {
         AVPacket *sub = ff_subtitles_queue_insert(q, buf->str, buf->len, 0);
         if (!sub)
             return AVERROR(ENOMEM);
         av_bprint_clear(buf);
         sub->pos = ei->pos;
         sub->pts = ei->pts;
         sub->duration = ei->duration;
         if (ei->x1 != -1) {
             uint8_t *p = av_packet_new_side_data(sub, AV_PKT_DATA_SUBTITLE_POSITION, 16);
             if (p) {
                 AV_WL32(p,      ei->x1);
                 AV_WL32(p +  4, ei->y1);
                 AV_WL32(p +  8, ei->x2);
                 AV_WL32(p + 12, ei->y2);
             }

         }
     }

 
     return 0;

 }
 

 static int srt_read_header(AVFormatContext *s)

 {

     SRTContext *srt = s->priv_data;

     AVBPrint buf;

     AVStream *st = avformat_new_stream(s, NULL);
     int res = 0;

     char line[4096], line_cache[4096];
     int has_event_info = 0;
     struct event_info ei;

     FFTextReader tr;

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

 
     if (!st)
         return AVERROR(ENOMEM);
     avpriv_set_pts_info(st, 64, 1, 1000);
     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
     st->codec->codec_id   = AV_CODEC_ID_SUBRIP;

     av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);

     line_cache[0] = 0;
 

     while (!ff_text_eof(&tr)) {

         struct event_info tmp_ei;
         const int64_t pos = ff_text_pos(&tr);
         ptrdiff_t len = ff_subtitles_read_line(&tr, line, sizeof(line));
 
         if (len < 0)
             break;
 
         if (!len || !line[0])
             continue;
 
         if (get_event_info(line, &tmp_ei) < 0) {
             char *pline;
 
             if (!has_event_info)
                 continue;
 
             if (line_cache[0]) {
                 /* We got some cache and a new line so we assume the cached
                  * line was actually part of the payload */
                 av_bprintf(&buf, "%s\n", line_cache);
                 line_cache[0] = 0;
             }
 
             /* If the line doesn't start with a number, we assume it's part of
              * the payload, otherwise is likely an event number preceding the
              * timing information... but we can't be sure of this yet, so we
              * cache it */
             if (strtol(line, &pline, 10) < 0 || line == pline)
                 av_bprintf(&buf, "%s\n", line);
             else
                 strcpy(line_cache, line);
         } else {
             if (has_event_info) {
                 /* We have the information of previous event, append it to the
                  * queue. We insert the cached line if and only if the payload
                  * is empty and the cached line is not a standalone number. */
                 char *pline = NULL;
                 const int standalone_number = strtol(line_cache, &pline, 10) >= 0 && pline && !*pline;
                 res = add_event(&srt->q, &buf, line_cache, &ei, !buf.len && !standalone_number);
                 if (res < 0)

                     goto end;

             } else {
                 has_event_info = 1;

             }

             tmp_ei.pos = pos;
             ei = tmp_ei;

         }

     }

     /* Append the last event. Here we force the cache to be flushed, because a
      * trailing number is more likely to be geniune (for example a copyright
      * date) and not the event index of an inexistant event */
     if (has_event_info) {
         res = add_event(&srt->q, &buf, line_cache, &ei, 1);
         if (res < 0)
             goto end;
     }
 

     ff_subtitles_queue_finalize(s, &srt->q);

 
 end:

     av_bprint_finalize(&buf, NULL);

     return res;
 }
 

 static int srt_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     SRTContext *srt = s->priv_data;
     return ff_subtitles_queue_read_packet(&srt->q, pkt);
 }
 
 static int srt_read_seek(AVFormatContext *s, int stream_index,
                          int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     SRTContext *srt = s->priv_data;
     return ff_subtitles_queue_seek(&srt->q, s, stream_index,
                                    min_ts, ts, max_ts, flags);
 }
 
 static int srt_read_close(AVFormatContext *s)
 {
     SRTContext *srt = s->priv_data;
     ff_subtitles_queue_clean(&srt->q);
     return 0;
 }
 

 AVInputFormat ff_srt_demuxer = {

     .name        = "srt",

     .long_name   = NULL_IF_CONFIG_SMALL("SubRip subtitle"),

     .priv_data_size = sizeof(SRTContext),

     .read_probe  = srt_probe,
     .read_header = srt_read_header,
     .read_packet = srt_read_packet,

     .read_seek2  = srt_read_seek,
     .read_close  = srt_read_close,

 };