module.exports = function(hljs) {
  var XML_IDENT_RE = '[A-Za-z0-9\\._:-]+';
  var PHP = {
    begin: /<\?(php)?(?!\w)/, end: /\?>/,
    subLanguage: 'php'
  };
  var TAG_INTERNALS = {
    endsWithParent: true,
    illegal: /</,
    relevance: 0,
    contains: [
      PHP,
      {
        className: 'attribute',
        begin: XML_IDENT_RE,
        relevance: 0
      },
      {
        begin: '=',
        relevance: 0,
        contains: [
          {
            className: 'value',
            contains: [PHP],
            variants: [
              {begin: /"/, end: /"/},
              {begin: /'/, end: /'/},
              {begin: /[^\s\/>]+/}
            ]
          }
        ]
      }
    ]
  };
  return {
    aliases: ['html', 'xhtml', 'rss', 'atom', 'xsl', 'plist'],
    case_insensitive: true,
    contains: [
      {
        className: 'doctype',
        begin: '<!DOCTYPE', end: '>',
        relevance: 10,
        contains: [{begin: '\\[', end: '\\]'}]
      },
      hljs.COMMENT(
        '<!--',
        '-->',
        {
          relevance: 10
        }
      ),
      {
        className: 'cdata',
        begin: '<\\!\\[CDATA\\[', end: '\\]\\]>',
        relevance: 10
      },
      {
        className: 'tag',
        /*
        The lookahead pattern (?=...) ensures that 'begin' only matches
        '<style' as a single word, followed by a whitespace or an
        ending braket. The '$' is needed for the lexeme to be recognized
        by hljs.subMode() that tests lexemes outside the stream.
        */
        begin: '<style(?=\\s|>|$)', end: '>',
        keywords: {title: 'style'},
        contains: [TAG_INTERNALS],
        starts: {
          end: '</style>', returnEnd: true,
          subLanguage: 'css'
        }
      },
      {
        className: 'tag',
        // See the comment in the <style tag about the lookahead pattern
        begin: '<script(?=\\s|>|$)', end: '>',
        keywords: {title: 'script'},
        contains: [TAG_INTERNALS],
        starts: {
          end: '\<\/script\>', returnEnd: true,
          subLanguage: ['actionscript', 'javascript', 'handlebars']
        }
      },
      PHP,
      {
        className: 'pi',
        begin: /<\?\w+/, end: /\?>/,
        relevance: 10
      },
      {
        className: 'tag',
        begin: '</?', end: '/?>',
        contains: [
          {
            className: 'title', begin: /[^ \/><\n\t]+/, relevance: 0
          },
          TAG_INTERNALS
        ]
      }
    ]
  };
};