src/lib/shortcode.js

/**
 * Constatns for the Converter class.
 * @type {Object}
 */
const SHCodes = [
  // ``` + lang parameter
  'code',

  // ```
  'plain',
  'text',

  // ```lang
  'as3',
  'actionscript3',
  'bash',
  'shell',
  'cf',
  'coldfusion',
  'c-sharp',
  'csharp',
  'cpp',
  'c',
  'css',
  'delphi',
  'pas',
  'pascal',
  'diff',
  'patch',
  'erl',
  'erlang',
  'groovy',
  'js',
  'jscript',
  'javascript',
  'java',
  'jfx',
  'javafx',
  'perl',
  'pl',
  'php',
  'ps',
  'powershell',
  'py',
  'python',
  'rails',
  'ror',
  'ruby',
  'scala',
  'sql',
  'vb',
  'vbnet',
  'xml',
  'xhtml',
  'xslt',
  'html'
]

/**
 * String of the Code block.
 * @type {Object}
 */
const Block = {
  BeginPlain: '\n\n```\n',
  Begin: '\n\n```',
  End: '\n```\n\n'
}

/**
 * Remove the new line beginning and end of the code block.
 *
 * @param {String} text Code block text.
 *
 * @return {Text} New text.
 */
const trimLineBreak = (text) => {
  return text.replace(/^[\n]|[\n]$/g, '')
}

/**
 * Convert a SyntaxHighlighter shortcode to Markdown.
 *
 * @param {String} src Original text.
 * @param {String} code Shortcode name.
 * @param {Object} params Shortcode parameters.
 * @param {String} body Shortcode body.
 *
 * @return {String} Converted text.
 */
const convertSH = (src, code, params, body) => {
  const value = trimLineBreak(body)
  if (code === SHCodes[ 0 ]) {
    if (params.lang) {
      return Block.Begin + params.lang + '\n' + value + Block.End
    }

    return Block.BeginPlain + value + Block.End
  } else if (code === SHCodes[1] || code === SHCodes[2]) {
    return Block.BeginPlain + value + Block.End
  }

  for (let i = 3, max = SHCodes.length; i < max; ++i) {
    if (code === SHCodes[i]) {
      return Block.Begin + code + `\n` + value + Block.End
    }
  }

  return src
}

/**
 * Parse a WordPress shortcode ("code param1="value1" param2="value2").
 *
 * @param {String} text shortcode text.
 *
 * @return {Object} Parsed result.
 */
const parse = (text) => {
  const codes = text.split(' ')
  const obj   = { code: codes[0], params: {} }

  for (let i = 1, max = codes.length; i < max; ++i) {
    const params = codes[i].split('=')
    if (params.length === 1) {
      obj.params[params[0]] = ' '
    } else {
      obj.params[params[0]] = params[1].replace(/^"(.+(?="$))"$/, '$1')
    }
  }

  return obj
}

/**
 * Convert the WordPress's shotcode to Markdown.
 *
 * @return {String} Converted string.
 */
const ConvertShortCode = (text) => {
  return text.replace(/\[([^\]]+)]([^[]+)\[\/([^\]]+)]/igm, (src, $1, $2) => {
    const shortcode = parse($1)
    if (shortcode.code === 'caption') {
      return $2
    }

    return convertSH(src, shortcode.code, shortcode.params, $2)
  })
}

export default ConvertShortCode