/*
  * 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 "internal.h"
 #include "subtitles.h"
 #include "libavutil/bprint.h"
 #include "libavutil/intreadwrite.h"
 
 typedef struct SCCContext {
     FFDemuxSubtitlesQueue q;
 } SCCContext;
 
 static int scc_probe(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 -= 87;
     else if (x >= 'A')
         x -= 55;
     else
         x -= '0';
     return x;
 }
 
 static int scc_read_header(AVFormatContext *s)
 {
     SCCContext *scc = s->priv_data;
     AVStream *st = avformat_new_stream(s, NULL);
     char line[4096], line2[4096];
     int count = 0, ret = 0;
     ptrdiff_t len2, 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 (!ff_text_eof(&tr)) {
         const int64_t pos = ff_text_pos(&tr);
         char *saveptr = NULL, *lline;
         int hh1, mm1, ss1, fs1, i;
         int hh2, mm2, ss2, fs2;
         int64_t ts_start, ts_end;
         AVPacket *sub;
 
         if (count == 0) {
             while (!ff_text_eof(&tr)) {
                 len = ff_subtitles_read_line(&tr, line, sizeof(line));
                 if (len > 13)
                     break;
             }
         }
 
         if (!strncmp(line, "Scenarist_SCC V1.0", 18))
             continue;

         if (sscanf(line, "%d:%d:%d%*[:;]%d", &hh1, &mm1, &ss1, &fs1) != 4)

             continue;
 
         ts_start = (hh1 * 3600LL + mm1 * 60LL + ss1) * 1000LL + fs1 * 33;
 
         while (!ff_text_eof(&tr)) {
             len2 = ff_subtitles_read_line(&tr, line2, sizeof(line2));
             if (len2 > 13)
                 break;
         }

         if (sscanf(line2, "%d:%d:%d%*[:;]%d", &hh2, &mm2, &ss2, &fs2) != 4)

             continue;
 
         ts_end = (hh2 * 3600LL + mm2 * 60LL + ss2) * 1000LL + fs2 * 33;
         count++;
 
         lline = (char *)&line;
         lline += 12;
 
         for (i = 0; i < 4095; i += 3) {
             char *ptr = av_strtok(lline, " ", &saveptr);
             char c1, c2, c3, c4;
 
             if (!ptr)
                 break;
 
             if (sscanf(ptr, "%c%c%c%c", &c1, &c2, &c3, &c4) != 4)
                 break;
 
             lline = NULL;
             out[i+0] = 0xfc;
             out[i+1] = convert(c2) | (convert(c1) << 4);
             out[i+2] = convert(c4) | (convert(c3) << 4);
         }
         out[i] = 0;
 
         sub = ff_subtitles_queue_insert(&scc->q, out, i, 0);
         if (!sub)
             return AVERROR(ENOMEM);
 
         sub->pos = pos;
         sub->pts = ts_start;
         sub->duration = FFMAX(1200, ts_end - ts_start);
         memmove(line, line2, sizeof(line));
         FFSWAP(ptrdiff_t, len, len2);
     }
 
     ff_subtitles_queue_finalize(s, &scc->q);
 
     return ret;
 }
 
 static int scc_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     SCCContext *scc = s->priv_data;
     return ff_subtitles_queue_read_packet(&scc->q, pkt);
 }
 
 static int scc_read_seek(AVFormatContext *s, int stream_index,
                          int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     SCCContext *scc = s->priv_data;
     return ff_subtitles_queue_seek(&scc->q, s, stream_index,
                                    min_ts, ts, max_ts, flags);
 }
 
 static int scc_read_close(AVFormatContext *s)
 {
     SCCContext *scc = s->priv_data;
     ff_subtitles_queue_clean(&scc->q);
     return 0;
 }
 
 AVInputFormat ff_scc_demuxer = {
     .name           = "scc",
     .long_name      = NULL_IF_CONFIG_SMALL("Scenarist Closed Captions"),
     .priv_data_size = sizeof(SCCContext),
     .read_probe     = scc_probe,
     .read_header    = scc_read_header,
     .read_packet    = scc_read_packet,
     .read_seek2     = scc_read_seek,
     .read_close     = scc_read_close,
     .extensions     = "scc",
 };