/*
  * XSUB subtitle decoder
  * Copyright (c) 2007 Reimar Döffinger
  *
  * 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 "libavutil/mathematics.h"

 #include "libavutil/imgutils.h"

 #include "avcodec.h"

 #include "get_bits.h"

 #include "bytestream.h"
 

 static av_cold int decode_init(AVCodecContext *avctx) {

     avctx->pix_fmt = AV_PIX_FMT_PAL8;

     return 0;
 }
 

 static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };

 static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };

 static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {

     int i;
     int64_t ms = 0;
     if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
         return AV_NOPTS_VALUE;
     for (i = 0; i < sizeof(tc_offsets); i++) {
         uint8_t c = buf[tc_offsets[i]] - '0';
         if (c > 9) return AV_NOPTS_VALUE;
         ms = (ms + c) * tc_muls[i];
     }

     return ms - packet_time;

 }
 

 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,

                         AVPacket *avpkt) {
     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;

     AVSubtitle *sub = data;

     const uint8_t *buf_end = buf + buf_size;

     uint8_t *bitmap;

     int w, h, x, y, i, ret;

     int64_t packet_time = 0;

     GetBitContext gb;

     int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');

 
     // check that at least header fits

     if (buf_size < 27 + 7 * 2 + 4 * (3 + has_alpha)) {

         av_log(avctx, AV_LOG_ERROR, "coded frame size %d too small\n", buf_size);

         return -1;
     }
 

     // read start and end time
     if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
         av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
         return -1;
     }

     if (avpkt->pts != AV_NOPTS_VALUE)
         packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});
     sub->start_display_time = parse_timecode(buf +  1, packet_time);
     sub->end_display_time   = parse_timecode(buf + 14, packet_time);

     buf += 27;
 

     // read header
     w = bytestream_get_le16(&buf);
     h = bytestream_get_le16(&buf);

     if (av_image_check_size(w, h, 0, avctx) < 0)

         return -1;
     x = bytestream_get_le16(&buf);
     y = bytestream_get_le16(&buf);
     // skip bottom right position, it gives no new information
     bytestream_get_le16(&buf);
     bytestream_get_le16(&buf);

     // The following value is supposed to indicate the start offset
     // (relative to the palette) of the data for the second field,

     // however there are files in which it has a bogus value and thus

     // we just ignore it
     bytestream_get_le16(&buf);

     if (buf_end - buf < h + 3*4)
         return AVERROR_INVALIDDATA;
 

     // allocate sub and set values

     sub->rects =  av_mallocz(sizeof(*sub->rects));

     if (!sub->rects)
         return AVERROR(ENOMEM);
 

     sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));

     if (!sub->rects[0]) {
         av_freep(&sub->rects);
         return AVERROR(ENOMEM);
     }

     sub->rects[0]->x = x; sub->rects[0]->y = y;
     sub->rects[0]->w = w; sub->rects[0]->h = h;

     sub->rects[0]->type = SUBTITLE_BITMAP;

     sub->rects[0]->linesize[0] = w;
     sub->rects[0]->data[0] = av_malloc(w * h);

     sub->rects[0]->nb_colors = 4;

     sub->rects[0]->data[1] = av_mallocz(AVPALETTE_SIZE);
     if (!sub->rects[0]->data[0] || !sub->rects[0]->data[1]) {
         av_freep(&sub->rects[0]->data[1]);
         av_freep(&sub->rects[0]->data[0]);

         av_freep(&sub->rects[0]);
         av_freep(&sub->rects);
         return AVERROR(ENOMEM);
     }
     sub->num_rects = 1;

 
     // read palette

     for (i = 0; i < sub->rects[0]->nb_colors; i++)

         ((uint32_t*)sub->rects[0]->data[1])[i] = bytestream_get_be24(&buf);

 
     if (!has_alpha) {
         // make all except background (first entry) non-transparent
         for (i = 1; i < sub->rects[0]->nb_colors; i++)

             ((uint32_t *)sub->rects[0]->data[1])[i] |= 0xff000000;

     } else {
         for (i = 0; i < sub->rects[0]->nb_colors; i++)

             ((uint32_t *)sub->rects[0]->data[1])[i] |= *buf++ << 24;

     }

 #if FF_API_AVPICTURE
 FF_DISABLE_DEPRECATION_WARNINGS

 {
     AVSubtitleRect *rect;
     int j;

     rect = sub->rects[0];
     for (j = 0; j < 4; j++) {
         rect->pict.data[j] = rect->data[j];
         rect->pict.linesize[j] = rect->linesize[j];
     }

 }

 FF_ENABLE_DEPRECATION_WARNINGS
 #endif
 

     // process RLE-compressed data

     if ((ret = init_get_bits8(&gb, buf, buf_end - buf)) < 0)
         return ret;

     bitmap = sub->rects[0]->data[0];

     for (y = 0; y < h; y++) {

         // interlaced: do odd lines

         if (y == (h + 1) / 2) bitmap = sub->rects[0]->data[0] + w;

         for (x = 0; x < w; ) {
             int log2 = ff_log2_tab[show_bits(&gb, 8)];

             int run = get_bits(&gb, 14 - 4 * (log2 >> 1));

             int color = get_bits(&gb, 2);

             run = FFMIN(run, w - x);
             // run length 0 means till end of row
             if (!run) run = w - x;

             memset(bitmap, color, run);

             bitmap += run;
             x += run;
         }

         // interlaced, skip every second line
         bitmap += w;

         align_get_bits(&gb);
     }
     *data_size = 1;
     return buf_size;
 }
 

 AVCodec ff_xsub_decoder = {

     .name      = "xsub",

     .long_name = NULL_IF_CONFIG_SMALL("XSUB"),

     .type      = AVMEDIA_TYPE_SUBTITLE,

     .id        = AV_CODEC_ID_XSUB,

     .init      = decode_init,
     .decode    = decode_frame,

 };