/*
  * 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
  * WebVTT subtitle demuxer
  * @see http://dev.w3.org/html5/webvtt/
  */
 
 #include "avformat.h"
 #include "internal.h"
 #include "subtitles.h"
 #include "libavutil/bprint.h"
 #include "libavutil/intreadwrite.h"

 #include "libavutil/opt.h"

 
 typedef struct {

     const AVClass *class;

     FFDemuxSubtitlesQueue q;

     int kind;

 } WebVTTContext;
 
 static int webvtt_probe(AVProbeData *p)
 {
     const uint8_t *ptr = p->buf;
 
     if (AV_RB24(ptr) == 0xEFBBBF)
         ptr += 3;  /* skip UTF-8 BOM */
     if (!strncmp(ptr, "WEBVTT", 6) &&
         (!ptr[6] || strchr("\n\r\t ", ptr[6])))
         return AVPROBE_SCORE_MAX;
     return 0;
 }
 
 static int64_t read_ts(const char *s)
 {
     int hh, mm, ss, ms;

     if (sscanf(s, "%u:%u:%u.%u", &hh, &mm, &ss, &ms) == 4) return (hh*3600LL + mm*60LL + ss) * 1000LL + ms;
     if (sscanf(s,    "%u:%u.%u",      &mm, &ss, &ms) == 3) return (            mm*60LL + ss) * 1000LL + ms;

     return AV_NOPTS_VALUE;
 }
 
 static int webvtt_read_header(AVFormatContext *s)
 {
     WebVTTContext *webvtt = s->priv_data;
     AVBPrint header, cue;
     int res = 0;
     AVStream *st = avformat_new_stream(s, NULL);
 
     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_WEBVTT;

     st->disposition |= webvtt->kind;

 
     av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED);
     av_bprint_init(&cue,    0, AV_BPRINT_SIZE_UNLIMITED);
 
     for (;;) {

         int i;
         int64_t pos;

         AVPacket *sub;

         const char *p, *identifier, *settings;
         int identifier_len, settings_len;

         int64_t ts_start, ts_end;
 

         ff_subtitles_read_chunk(s->pb, &cue);
 
         if (!cue.len)

             break;
 

         p = identifier = cue.str;
         pos = avio_tell(s->pb);
 

         /* ignore header chunk */
         if (!strncmp(p, "\xEF\xBB\xBFWEBVTT", 9) ||
             !strncmp(p, "WEBVTT", 6))
             continue;
 
         /* optional cue identifier (can be a number like in SRT or some kind of

          * chaptering id) */
         for (i = 0; p[i] && p[i] != '\n' && p[i] != '\r'; i++) {

             if (!strncmp(p + i, "-->", 3)) {
                 identifier = NULL;
                 break;
             }
         }

         if (!identifier)
             identifier_len = 0;
         else {
             identifier_len = strcspn(p, "\r\n");
             p += identifier_len;
             if (*p == '\r')
                 p++;
             if (*p == '\n')
                 p++;
         }

 
         /* cue timestamps */
         if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE)
             break;
         if (!(p = strstr(p, "-->")))
             break;

         p += 2;

         do p++; while (*p == ' ' || *p == '\t');
         if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE)
             break;
 

         /* optional cue settings */

         p += strcspn(p, "\n\t ");
         while (*p == '\t' || *p == ' ')
             p++;

         settings = p;
         settings_len = strcspn(p, "\r\n");
         p += settings_len;
         if (*p == '\r')
             p++;

         if (*p == '\n')
             p++;
 
         /* create packet */

         sub = ff_subtitles_queue_insert(&webvtt->q, p, strlen(p), 0);

         if (!sub) {
             res = AVERROR(ENOMEM);
             goto end;
         }
         sub->pos = pos;
         sub->pts = ts_start;
         sub->duration = ts_end - ts_start;

 #define SET_SIDE_DATA(name, type) do {                                  \
     if (name##_len) {                                                   \
         uint8_t *buf = av_packet_new_side_data(sub, type, name##_len);  \
         if (!buf) {                                                     \
             res = AVERROR(ENOMEM);                                      \
             goto end;                                                   \
         }                                                               \
         memcpy(buf, name, name##_len);                                  \
     }                                                                   \
 } while (0)
 
         SET_SIDE_DATA(identifier, AV_PKT_DATA_WEBVTT_IDENTIFIER);
         SET_SIDE_DATA(settings,   AV_PKT_DATA_WEBVTT_SETTINGS);

     }
 
     ff_subtitles_queue_finalize(&webvtt->q);
 
 end:
     av_bprint_finalize(&cue,    NULL);
     av_bprint_finalize(&header, NULL);
     return res;
 }
 
 static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     WebVTTContext *webvtt = s->priv_data;
     return ff_subtitles_queue_read_packet(&webvtt->q, pkt);
 }
 

 static int webvtt_read_seek(AVFormatContext *s, int stream_index,
                             int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     WebVTTContext *webvtt = s->priv_data;
     return ff_subtitles_queue_seek(&webvtt->q, s, stream_index,
                                    min_ts, ts, max_ts, flags);
 }
 

 static int webvtt_read_close(AVFormatContext *s)
 {
     WebVTTContext *webvtt = s->priv_data;
     ff_subtitles_queue_clean(&webvtt->q);
     return 0;
 }
 

 #define OFFSET(x) offsetof(WebVTTContext, x)
 #define KIND_FLAGS AV_OPT_FLAG_SUBTITLE_PARAM
 
 static const AVOption options[] = {
     { "kind", "Set kind of WebVTT track", OFFSET(kind), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, KIND_FLAGS, "webvtt_kind" },
         { "subtitles",    "WebVTT subtitles kind",    0, AV_OPT_TYPE_CONST, { .i64 = 0 },                           INT_MIN, INT_MAX, 0, "webvtt_kind" },
         { "captions",     "WebVTT captions kind",     0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS },     INT_MIN, INT_MAX, 0, "webvtt_kind" },
         { "descriptions", "WebVTT descriptions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
         { "metadata",     "WebVTT metadata kind",     0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA },     INT_MIN, INT_MAX, 0, "webvtt_kind" },
     { NULL }
 };
 
 static const AVClass webvtt_demuxer_class = {
     .class_name  = "WebVTT demuxer",
     .item_name   = av_default_item_name,
     .option      = options,
     .version     = LIBAVUTIL_VERSION_INT,
 };
 

 AVInputFormat ff_webvtt_demuxer = {
     .name           = "webvtt",
     .long_name      = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
     .priv_data_size = sizeof(WebVTTContext),
     .read_probe     = webvtt_probe,
     .read_header    = webvtt_read_header,
     .read_packet    = webvtt_read_packet,

     .read_seek2     = webvtt_read_seek,

     .read_close     = webvtt_read_close,
     .extensions     = "vtt",

     .priv_class     = &webvtt_demuxer_class,

 };