/*
  * 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 decoder
  * @see http://dev.w3.org/html5/webvtt/
  * @todo need to support extended markups and cue settings
  */
 
 #include "avcodec.h"
 #include "ass.h"
 #include "libavutil/bprint.h"
 
 static const struct {
     const char *from;
     const char *to;
 } webvtt_tag_replace[] = {
     {"<i>", "{\\i1}"}, {"</i>", "{\\i0}"},
     {"<b>", "{\\b1}"}, {"</b>", "{\\b0}"},
     {"<u>", "{\\u1}"}, {"</u>", "{\\u0}"},
     {"{", "\\{"}, {"}", "\\}"}, // escape to avoid ASS markup conflicts

     {"&gt;", ">"}, {"&lt;", "<"},
     {"&lrm;", ""}, {"&rlm;", ""}, // FIXME: properly honor bidi marks
     {"&amp;", "&"}, {"&nbsp;", "\\h"},

 };
 
 static int webvtt_event_to_ass(AVBPrint *buf, const char *p)
 {

     int i, again = 0, skip = 0;

 
     while (*p) {
 
         for (i = 0; i < FF_ARRAY_ELEMS(webvtt_tag_replace); i++) {
             const char *from = webvtt_tag_replace[i].from;
             const size_t len = strlen(from);
             if (!strncmp(p, from, len)) {
                 av_bprintf(buf, "%s", webvtt_tag_replace[i].to);
                 p += len;

                 again = 1;

                 break;
             }
         }
         if (!*p)
             break;
 

         if (again) {
             again = 0;
             skip = 0;
             continue;
         }

         if (*p == '<')
             skip = 1;
         else if (*p == '>')
             skip = 0;
         else if (p[0] == '\n' && p[1])
             av_bprintf(buf, "\\N");
         else if (!skip && *p != '\r')
             av_bprint_chars(buf, *p, 1);
         p++;
     }
     return 0;
 }
 
 static int webvtt_decode_frame(AVCodecContext *avctx,
                                void *data, int *got_sub_ptr, AVPacket *avpkt)
 {

     int ret = 0;

     AVSubtitle *sub = data;
     const char *ptr = avpkt->data;
     AVBPrint buf;
 
     av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
     if (ptr && avpkt->size > 0 && !webvtt_event_to_ass(&buf, ptr)) {
         int ts_start     = av_rescale_q(avpkt->pts, avctx->time_base, (AVRational){1,100});
         int ts_duration  = avpkt->duration != -1 ?
                            av_rescale_q(avpkt->duration, avctx->time_base, (AVRational){1,100}) : -1;

         ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_duration);

     }
     av_bprint_finalize(&buf, NULL);

     if (ret < 0)
         return ret;
     *got_sub_ptr = sub->num_rects > 0;

     return avpkt->size;
 }
 
 AVCodec ff_webvtt_decoder = {
     .name           = "webvtt",
     .long_name      = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
     .type           = AVMEDIA_TYPE_SUBTITLE,
     .id             = AV_CODEC_ID_WEBVTT,
     .decode         = webvtt_decode_frame,
     .init           = ff_ass_subtitle_header_default,
 };