/*
  * DivX (XSUB) subtitle encoder
  * Copyright (c) 2005 DivX, Inc.
  * Copyright (c) 2009 Bjorn Axelsson
  *
  * 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 "avcodec.h"
 #include "bytestream.h"
 #include "put_bits.h"
 
 /**
  * Number of pixels to pad left and right.
  *
  * The official encoder pads the subtitles with two pixels on either side,
  * but until we find out why, we won't do it (we will pad to have width
  * divisible by 2 though).
  */
 #define PADDING 0
 #define PADDING_COLOR 0
 
 /**

  * Encode a single color run. At most 16 bits will be used.

  * @param len   length of the run, values > 255 mean "until end of line", may not be < 0.
  * @param color color to encode, only the lowest two bits are used and all others must be 0.

  */
 static void put_xsub_rle(PutBitContext *pb, int len, int color)
 {
     if (len <= 255)
         put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len);
     else
         put_bits(pb, 14, 0);
     put_bits(pb, 2, color);
 }
 
 /**

  * Encode a 4-color bitmap with XSUB rle.

  *
  * The encoded bitmap may be wider than the source bitmap due to padding.
  */
 static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap,
                            int linesize, int w, int h)
 {
     int x0, x1, y, len, color = PADDING_COLOR;
 
     for (y = 0; y < h; y++) {
         x0 = 0;
         while (x0 < w) {
             // Make sure we have enough room for at least one run and padding
             if (pb->size_in_bits - put_bits_count(pb) < 7*8)
                 return -1;
 
             x1 = x0;
             color = bitmap[x1++] & 3;
             while (x1 < w && (bitmap[x1] & 3) == color)
                 x1++;
             len = x1 - x0;
             if (PADDING && x0 == 0) {
                 if (color == PADDING_COLOR) {
                     len += PADDING;
                     x0  -= PADDING;
                 } else
                     put_xsub_rle(pb, PADDING, PADDING_COLOR);
             }
 
             // Run can't be longer than 255, unless it is the rest of a row
             if (x1 == w && color == PADDING_COLOR) {
                 len += PADDING + (w&1);
             } else
                 len = FFMIN(len, 255);
             put_xsub_rle(pb, len, color);
 
             x0 += len;
         }
         if (color != PADDING_COLOR && (PADDING + (w&1)))
             put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR);
 

         avpriv_align_put_bits(pb);

 
         bitmap += linesize;
     }
 
     return 0;
 }
 
 static int make_tc(uint64_t ms, int *tc)
 {
     static const int tc_divs[3] = { 1000, 60, 60 };
     int i;
     for (i=0; i<3; i++) {
         tc[i] = ms % tc_divs[i];
         ms /= tc_divs[i];
     }
     tc[3] = ms;
     return ms > 99;
 }
 
 static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,

                        int bufsize, const AVSubtitle *h)

 {
     uint64_t startTime = h->pts / 1000; // FIXME: need better solution...
     uint64_t endTime = startTime + h->end_display_time - h->start_display_time;
     int start_tc[4], end_tc[4];
     uint8_t *hdr = buf + 27; // Point behind the timestamp
     uint8_t *rlelenptr;
     uint16_t width, height;
     int i;
     PutBitContext pb;
 
     if (bufsize < 27 + 7*2 + 4*3) {
         av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");
         return -1;
     }
 
     // TODO: support multiple rects

     if (h->num_rects != 1)

         av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);
 
     // TODO: render text-based subtitles into bitmaps
     if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) {
         av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");
         return -1;
     }
 
     // TODO: color reduction, similar to dvdsub encoder
     if (h->rects[0]->nb_colors > 4)
         av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);
 
     // TODO: Palette swapping if color zero is not transparent

     if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff000000)

         av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");
 
     if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {
         av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");
         return -1;
     }
 
     snprintf(buf, 28,
         "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",
         start_tc[3], start_tc[2], start_tc[1], start_tc[0],

         end_tc[3],   end_tc[2],   end_tc[1],   end_tc[0]);

 
     // Width and height must probably be multiples of 2.
     // 2 pixels required on either side of subtitle.
     // Possibly due to limitations of hardware renderers.
     // TODO: check if the bitmap is already padded
     width  = FFALIGN(h->rects[0]->w, 2) + PADDING * 2;
     height = FFALIGN(h->rects[0]->h, 2);
 
     bytestream_put_le16(&hdr, width);
     bytestream_put_le16(&hdr, height);
     bytestream_put_le16(&hdr, h->rects[0]->x);
     bytestream_put_le16(&hdr, h->rects[0]->y);

     bytestream_put_le16(&hdr, h->rects[0]->x + width -1);
     bytestream_put_le16(&hdr, h->rects[0]->y + height -1);

 
     rlelenptr = hdr; // Will store length of first field here later.
     hdr+=2;
 
     // Palette
     for (i=0; i<4; i++)
         bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]);
 
     // Bitmap
     // RLE buffer. Reserve 2 bytes for possible padding after the last row.
     init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2);
     if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0],
                         h->rects[0]->pict.linesize[0]*2,
                         h->rects[0]->w, (h->rects[0]->h + 1) >> 1))
         return -1;
     bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field
 
     if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0],
                         h->rects[0]->pict.linesize[0]*2,
                         h->rects[0]->w, h->rects[0]->h >> 1))
         return -1;
 

     // Enforce total height to be a multiple of 2

     if (h->rects[0]->h & 1) {
         put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR);

         avpriv_align_put_bits(&pb);

     }
 
     flush_put_bits(&pb);
 
     return hdr - buf + put_bits_count(&pb)/8;
 }
 
 static av_cold int xsub_encoder_init(AVCodecContext *avctx)
 {
     if (!avctx->codec_tag)
         avctx->codec_tag = MKTAG('D','X','S','B');
 

     avctx->bits_per_coded_sample = 4;
 

     return 0;
 }
 

 AVCodec ff_xsub_encoder = {

     .name       = "xsub",

     .long_name  = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"),

     .type       = AVMEDIA_TYPE_SUBTITLE,
     .id         = AV_CODEC_ID_XSUB,
     .init       = xsub_encoder_init,
     .encode_sub = xsub_encode,

 };