/*
  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>

  * Copyright (c) 2017  Clément Bœsch <u@pkh.me>

  *
  * 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/avassert.h"

 #include "libavutil/avstring.h"
 #include "libavutil/common.h"
 #include "libavutil/parseutils.h"
 #include "htmlsubtitles.h"

 #include <ctype.h>

 static int html_color_parse(void *log_ctx, const char *str)

 {
     uint8_t rgba[4];

     int nb_sharps = 0;
     while (str[nb_sharps] == '#')
         nb_sharps++;
     str += FFMAX(0, nb_sharps - 1);

     if (av_parse_color(rgba, str, strcspn(str, "\" >"), log_ctx) < 0)

         return -1;
     return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
 }
 
 static void rstrip_spaces_buf(AVBPrint *buf)
 {

     if (av_bprint_is_complete(buf))
         while (buf->len > 0 && buf->str[buf->len - 1] == ' ')
             buf->str[--buf->len] = 0;

 }
 

 /*
  * Fast code for scanning text enclosed in braces. Functionally
  * equivalent to this sscanf call:
  *
  * sscanf(in, "{\\an%*1u}%n", &len) >= 0 && len > 0
  */
 static int scanbraces(const char* in) {
     if (strncmp(in, "{\\an", 4) != 0) {
         return 0;
     }

     if (!av_isdigit(in[4])) {

         return 0;
     }
     if (in[5] != '}') {
         return 0;
     }
     return 1;
 }
 

 /* skip all {\xxx} substrings except for {\an%d}
    and all microdvd like styles such as {Y:xxx} */
 static void handle_open_brace(AVBPrint *dst, const char **inp, int *an, int *closing_brace_missing)
 {
     const char *in = *inp;
 

     *an += scanbraces(in);

 
     if (!*closing_brace_missing) {
         if (   (*an != 1 && in[1] == '\\')
             || (in[1] && strchr("CcFfoPSsYy", in[1]) && in[2] == ':')) {
             char *bracep = strchr(in+2, '}');
             if (bracep) {
                 *inp = bracep;
                 return;
             } else
                 *closing_brace_missing = 1;
         }
     }
 
     av_bprint_chars(dst, *in, 1);
 }
 

 struct font_tag {
     char face[128];
     int size;
     uint32_t color;
 };
 
 /*

  * Fast code for scanning the rest of a tag. Functionally equivalent to
  * this sscanf call:
  *
  * sscanf(in, "%127[^<>]>%n", buffer, lenp) == 2
  */
 static int scantag(const char* in, char* buffer, int* lenp) {
     int len;
 
     for (len = 0; len < 128; len++) {
         const char c = *in++;
         switch (c) {
         case '\0':
             return 0;
         case '<':
             return 0;
         case '>':
             buffer[len] = '\0';
             *lenp = len+1;
             return 1;
         default:
             break;
         }
         buffer[len] = c;
     }
     return 0;
 }
 
 /*

  * The general politic of the convert is to mask unsupported tags or formatting
  * errors (but still alert the user/subtitles writer with an error/warning)
  * without dropping any actual text content for the final user.
  */

 int ff_htmlmarkup_to_ass(void *log_ctx, AVBPrint *dst, const char *in)

 {

     char *param, buffer[128];
     int len, tag_close, sptr = 0, line_start = 1, an = 0, end = 0;

     int closing_brace_missing = 0;

     int i, likely_a_tag;

     /*
      * state stack is only present for fonts since they are the only tags where
      * the state is not binary. Here is a typical use case:
      *
      *   <font color="red" size=10>
      *     red 10
      *     <font size=50> RED AND BIG </font>
      *     red 10 again
      *   </font>
      *
      * On the other hand, using the state system for all the tags should be
      * avoided because it breaks wrongly nested tags such as:
      *
      *   <b> foo <i> bar </b> bla </i>
      *
      * We don't want to break here; instead, we will treat all these tags as
      * binary state markers. Basically, "<b>" will activate bold, and "</b>"
      * will deactivate it, whatever the current state.
      *
      * This will also prevents cases where we have a random closing tag
      * remaining after the opening one was dropped. Yes, this happens and we
      * still don't want to print a "</b>" at the end of the dialog event.
      */
     struct font_tag stack[16];
 
     memset(&stack[0], 0, sizeof(stack[0]));

 
     for (; !end && *in; in++) {
         switch (*in) {
         case '\r':
             break;
         case '\n':
             if (line_start) {
                 end = 1;
                 break;
             }
             rstrip_spaces_buf(dst);
             av_bprintf(dst, "\\N");
             line_start = 1;
             break;
         case ' ':
             if (!line_start)
                 av_bprint_chars(dst, *in, 1);
             break;

         case '{':
             handle_open_brace(dst, &in, &an, &closing_brace_missing);

             break;
         case '<':

             /*
              * "<<" are likely latin guillemets in ASCII or some kind of random
              * style effect; see sub/badsyntax.srt in the FATE samples
              * directory for real test cases.
              */
 
             likely_a_tag = 1;
             for (i = 0; in[1] == '<'; i++) {
                 av_bprint_chars(dst, '<', 1);
                 likely_a_tag = 0;
                 in++;
             }
 

             tag_close = in[1] == '/';

             if (tag_close)
                 likely_a_tag = 1;
 
             av_assert0(in[0] == '<');
 

             len = 0;

             if (scantag(in+tag_close+1, buffer, &len) && len > 0) {

                 const int skip = len + tag_close;

                 const char *tagname = buffer;

                 while (*tagname == ' ') {
                     likely_a_tag = 0;

                     tagname++;

                 }

                 if ((param = strchr(tagname, ' ')))

                     *param++ = 0;

 
                 /* Check if this is likely a tag */
 #define LIKELY_A_TAG_CHAR(x) (((x) >= '0' && (x) <= '9') || \
                               ((x) >= 'a' && (x) <= 'z') || \
                               ((x) >= 'A' && (x) <= 'Z') || \

                                (x) == '_' || (x) == '/')

                 for (i = 0; tagname[i]; i++) {
                     if (!LIKELY_A_TAG_CHAR(tagname[i])) {
                         likely_a_tag = 0;
                         break;
                     }
                 }
 
                 if (!av_strcasecmp(tagname, "font")) {
                     if (tag_close && sptr > 0) {
                         struct font_tag *cur_tag  = &stack[sptr--];
                         struct font_tag *last_tag = &stack[sptr];
 
                         if (cur_tag->size) {
                             if (!last_tag->size)
                                 av_bprintf(dst, "{\\fs}");
                             else if (last_tag->size != cur_tag->size)
                                 av_bprintf(dst, "{\\fs%d}", last_tag->size);
                         }
 
                         if (cur_tag->color & 0xff000000) {
                             if (!(last_tag->color & 0xff000000))
                                 av_bprintf(dst, "{\\c}");
                             else if (last_tag->color != cur_tag->color)

                                 av_bprintf(dst, "{\\c&H%"PRIX32"&}", last_tag->color & 0xffffff);

                         }
 
                         if (cur_tag->face[0]) {
                             if (!last_tag->face[0])
                                 av_bprintf(dst, "{\\fn}");
                             else if (strcmp(last_tag->face, cur_tag->face))
                                 av_bprintf(dst, "{\\fn%s}", last_tag->face);
                         }
                     } else if (!tag_close && sptr < FF_ARRAY_ELEMS(stack) - 1) {
                         struct font_tag *new_tag = &stack[sptr + 1];
 
                         *new_tag = stack[sptr++];
 

                         while (param) {
                             if (!av_strncasecmp(param, "size=", 5)) {
                                 param += 5 + (param[5] == '"');
                                 if (sscanf(param, "%u", &new_tag->size) == 1)
                                     av_bprintf(dst, "{\\fs%u}", new_tag->size);
                             } else if (!av_strncasecmp(param, "color=", 6)) {
                                 int color;
                                 param += 6 + (param[6] == '"');
                                 color = html_color_parse(log_ctx, param);
                                 if (color >= 0) {
                                     new_tag->color = 0xff000000 | color;

                                     av_bprintf(dst, "{\\c&H%"PRIX32"&}", new_tag->color & 0xffffff);

                                 }

                             } else if (!av_strncasecmp(param, "face=", 5)) {
                                 param += 5 + (param[5] == '"');
                                 len = strcspn(param,
                                               param[-1] == '"' ? "\"" :" ");
                                 av_strlcpy(new_tag->face, param,
                                            FFMIN(sizeof(new_tag->face), len+1));
                                 param += len;
                                 av_bprintf(dst, "{\\fn%s}", new_tag->face);

                             }

                             if ((param = strchr(param, ' ')))
                                 param++;

                         }

                     }

                     in += skip;

                 } else if (tagname[0] && !tagname[1] && strchr("bisu", av_tolower(tagname[0]))) {
                     av_bprintf(dst, "{\\%c%d}", (char)av_tolower(tagname[0]), !tag_close);
                     in += skip;
                 } else if (!av_strncasecmp(tagname, "br", 2) &&
                            (!tagname[2] || (tagname[2] == '/' && !tagname[3]))) {
                     av_bprintf(dst, "\\N");
                     in += skip;
                 } else if (likely_a_tag) {
                     if (!tag_close) // warn only once
                         av_log(log_ctx, AV_LOG_WARNING, "Unrecognized tag %s\n", tagname);
                     in += skip;
                 } else {
                     av_bprint_chars(dst, '<', 1);

                 }

             } else {
                 av_bprint_chars(dst, *in, 1);

             }

             break;

         default:
             av_bprint_chars(dst, *in, 1);
             break;
         }
         if (*in != ' ' && *in != '\r' && *in != '\n')
             line_start = 0;
     }
 

     if (!av_bprint_is_complete(dst))
         return AVERROR(ENOMEM);
 

     while (dst->len >= 2 && !strncmp(&dst->str[dst->len - 2], "\\N", 2))
         dst->len -= 2;
     dst->str[dst->len] = 0;
     rstrip_spaces_buf(dst);

 
     return 0;

 }