const rsAstralRange = '\\ud800-\\udfff',
  rsComboMarksRange = '\\u0300-\\u036f',
  reComboHalfMarksRange = '\\ufe20-\\ufe2f',
  rsComboSymbolsRange = '\\u20d0-\\u20ff',
  rsComboRange =
    rsComboMarksRange + reComboHalfMarksRange + rsComboSymbolsRange,
  rsVarRange = '\\ufe0e\\ufe0f'

/** Used to compose unicode capture groups. */
const rsAstral = `[${rsAstralRange}]`,
  rsCombo = `[${rsComboRange}]`,
  rsFitz = '\\ud83c[\\udffb-\\udfff]',
  rsModifier = `(?:${rsCombo}|${rsFitz})`,
  rsNonAstral = `[^${rsAstralRange}]`,
  rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}',
  rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
  rsZWJ = '\\u200d'

/** Used to compose unicode regexes. */
const reOptMod = `${rsModifier}?`,
  rsOptVar = `[${rsVarRange}]?`,
  rsOptJoin = `(?:${rsZWJ}(?:${[rsNonAstral, rsRegional, rsSurrPair].join(
    '|'
  )})${rsOptVar}${reOptMod})*`,
  rsSeq = rsOptVar + reOptMod + rsOptJoin,
  rsSymbol = `(?:${[
    `${rsNonAstral + rsCombo}?`,
    rsCombo,
    rsRegional,
    rsSurrPair,
    rsAstral,
  ].join('|')})`

/** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
const reUnicode = new RegExp(`${rsFitz}(?=${rsFitz})|${rsSymbol}${rsSeq}`, 'g')

/**
 * Converts a Unicode `string` to an array.
 *
 * @private
 * @param {string} string The string to convert.
 * @returns {Array} Returns the converted array.
 */
export function unicodeToArray(string: string) {
  return string.match(reUnicode) || []
}
