/*
  * 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
  */
 
 #include "avformat.h"
 #include "subtitles.h"

 #include "libavutil/avstring.h"

 
 AVPacket *ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q,
                                     const uint8_t *event, int len, int merge)
 {
     AVPacket *subs, *sub;
 
     if (merge && q->nb_subs > 0) {
         /* merge with previous event */
 
         int old_len;
         sub = &q->subs[q->nb_subs - 1];
         old_len = sub->size;
         if (av_grow_packet(sub, len) < 0)
             return NULL;
         memcpy(sub->data + old_len, event, len);
     } else {
         /* new event */
 
         if (q->nb_subs >= INT_MAX/sizeof(*q->subs) - 1)
             return NULL;
         subs = av_fast_realloc(q->subs, &q->allocated_size,
                                (q->nb_subs + 1) * sizeof(*q->subs));
         if (!subs)
             return NULL;
         q->subs = subs;
         sub = &subs[q->nb_subs++];
         if (av_new_packet(sub, len) < 0)
             return NULL;
         sub->destruct = NULL;
         sub->flags |= AV_PKT_FLAG_KEY;
         sub->pts = sub->dts = 0;
         memcpy(sub->data, event, len);
     }
     return sub;
 }
 
 static int cmp_pkt_sub(const void *a, const void *b)
 {
     const AVPacket *s1 = a;
     const AVPacket *s2 = b;
     if (s1->pts == s2->pts) {
         if (s1->pos == s2->pos)
             return 0;
         return s1->pos > s2->pos ? 1 : -1;
     }
     return s1->pts > s2->pts ? 1 : -1;
 }
 
 void ff_subtitles_queue_finalize(FFDemuxSubtitlesQueue *q)
 {
     int i;
 
     qsort(q->subs, q->nb_subs, sizeof(*q->subs), cmp_pkt_sub);
     for (i = 0; i < q->nb_subs; i++)
         if (q->subs[i].duration == -1 && i < q->nb_subs - 1)
             q->subs[i].duration = q->subs[i + 1].pts - q->subs[i].pts;
 }
 
 int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
 {
     AVPacket *sub = q->subs + q->current_sub_idx;
 
     if (q->current_sub_idx == q->nb_subs)
         return AVERROR_EOF;
     *pkt = *sub;
     pkt->dts = pkt->pts;
     q->current_sub_idx++;
     return 0;
 }
 

 int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index,
                             int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     if (flags & AVSEEK_FLAG_BYTE) {
         return AVERROR(ENOSYS);
     } else if (flags & AVSEEK_FLAG_FRAME) {
         if (ts < 0 || ts >= q->nb_subs)
             return AVERROR(ERANGE);
         q->current_sub_idx = ts;
     } else {
         int i, idx = -1;
         int64_t min_ts_diff = INT64_MAX;

         int64_t ts_selected;

         /* TODO: q->subs[] is sorted by pts so we could do a binary search */
         for (i = 0; i < q->nb_subs; i++) {
             int64_t pts = q->subs[i].pts;
             uint64_t ts_diff = FFABS(pts - ts);

             if ((stream_index == -1 || q->subs[i].stream_index == stream_index) &&
                 pts >= min_ts && pts <= max_ts && ts_diff < min_ts_diff) {

                 min_ts_diff = ts_diff;
                 idx = i;
             }
         }
         if (idx < 0)
             return AVERROR(ERANGE);

         /* look back in the latest subtitles for overlapping subtitles */
         ts_selected = q->subs[idx].pts;
         for (i = idx - 1; i >= 0; i--) {

             int64_t pts = q->subs[i].pts;

             if (q->subs[i].duration <= 0 ||
                 (stream_index != -1 && q->subs[i].stream_index != stream_index))

                 continue;

             if (pts >= min_ts && pts > ts_selected - q->subs[i].duration)

                 idx = i;
             else
                 break;
         }

 
         /* If the queue is used to store multiple subtitles streams (like with
          * VobSub) and the stream index is not specified, we need to make sure
          * to focus on the smallest file position offset for a same timestamp;
          * queue is ordered by pts and then filepos, so we can take the first
          * entry for a given timestamp. */
         if (stream_index == -1)
             while (idx > 0 && q->subs[idx - 1].pts == q->subs[idx].pts)
                 idx--;
 

         q->current_sub_idx = idx;
     }
     return 0;
 }
 

 void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
 {
     int i;
 
     for (i = 0; i < q->nb_subs; i++)
         av_destruct_packet(&q->subs[i]);
     av_freep(&q->subs);
     q->nb_subs = q->allocated_size = q->current_sub_idx = 0;
 }

 
 int ff_smil_extract_next_chunk(AVIOContext *pb, AVBPrint *buf, char *c)
 {
     int i = 0;
     char end_chr;
 
     if (!*c) // cached char?
         *c = avio_r8(pb);
     if (!*c)
         return 0;
 
     end_chr = *c == '<' ? '>' : '<';
     do {
         av_bprint_chars(buf, *c, 1);
         *c = avio_r8(pb);
         i++;
     } while (*c != end_chr && *c);
     if (end_chr == '>') {
         av_bprint_chars(buf, '>', 1);
         *c = 0;
     }
     return i;
 }
 
 const char *ff_smil_get_attr_ptr(const char *s, const char *attr)
 {
     int in_quotes = 0;
     const int len = strlen(attr);
 
     while (*s) {
         while (*s) {
             if (!in_quotes && isspace(*s))
                 break;
             in_quotes ^= *s == '"'; // XXX: support escaping?
             s++;
         }
         while (isspace(*s))
             s++;
         if (!av_strncasecmp(s, attr, len) && s[len] == '=')
             return s + len + 1 + (s[len + 1] == '"');
     }
     return NULL;
 }

 
 static inline int is_eol(char c)
 {
     return c == '\r' || c == '\n';
 }
 
 void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf)
 {
     char eol_buf[5];
     int n = 0, i = 0, nb_eol = 0;
 
     av_bprint_clear(buf);
 
     for (;;) {
         char c = avio_r8(pb);
 
         if (!c)
             break;
 
         /* ignore all initial line breaks */
         if (n == 0 && is_eol(c))
             continue;
 
         /* line break buffering: we don't want to add the trailing \r\n */
         if (is_eol(c)) {
             nb_eol += c == '\n';
             if (nb_eol == 2)
                 break;
             eol_buf[i++] = c;
             if (i == sizeof(eol_buf) - 1)
                 break;
             continue;
         }
 
         /* only one line break followed by data: we flush the line breaks
          * buffer */
         if (i) {
             eol_buf[i] = 0;
             av_bprintf(buf, "%s", eol_buf);
             i = nb_eol = 0;
         }
 
         av_bprint_chars(buf, c, 1);
         n++;
     }
 }