#include "tagfilter.h"

#include <parser.h>

#include <ctype.h>

static const char *blacklist[] = {

    "title",   "textarea", "style",  "xmp",       "iframe",

    "noembed", "noframes", "script", "plaintext", NULL,

};

static int is_tag(const unsigned char *tag_data, size_t tag_size,

                  const char *tagname) {

  size_t i;

  if (tag_size < 3 || tag_data[0] != '<')

    return 0;

  i = 1;

  if (tag_data[i] == '/') {

    i++;

  }

  for (; i < tag_size; ++i, ++tagname) {

    if (*tagname == 0)

      break;

    if (tolower(tag_data[i]) != *tagname)

      return 0;

  }

  if (i == tag_size)

    return 0;

  if (cmark_isspace(tag_data[i]) || tag_data[i] == '>')

    return 1;

  if (tag_data[i] == '/' && tag_size >= i + 2 && tag_data[i + 1] == '>')

    return 1;

  return 0;

}

static int filter(cmark_syntax_extension *ext, const unsigned char *tag,

                  size_t tag_len) {

  const char **it;

  for (it = blacklist; *it; ++it) {

    if (is_tag(tag, tag_len, *it)) {

      return 0;

    }

  }

  return 1;

}

cmark_syntax_extension *create_tagfilter_extension(void) {

  cmark_syntax_extension *ext = cmark_syntax_extension_new("tagfilter");

  cmark_syntax_extension_set_html_filter_func(ext, filter);

  return ext;

}