irclib/src/utility/message-formatting.ts

export const IRC_FMT_COLOR_MAP = {
  /**
   * IRC white `rgb(255,255,255)`
   */
  white: '\u00030',
  /**
   * IRC black `rgb(0,0,0)`
   */
  black: '\u00031',
  /**
   * IRC blue `rgb(0,0,127)`
   */
  blue: '\u00032',
  /**
   * IRC green `rgb(0,147,0)`
   */
  green: '\u00033',
  /**
   * IRC red `rgb(255,0,0)`
   */
  red: '\u00034',
  /**
   * IRC brown `rgb(127,0,0)`
   */
  brown: '\u00035',
  /**
   * IRC purple `rgb(156,0,156)`
   */
  purple: '\u00036',
  /**
   * IRC orange `rgb(252,127,0)`
   */
  orange: '\u00037',
  /**
   * IRC yellow `rgb(255,255,0)`
   */
  yellow: '\u00038',
  /**
   * IRC light green `rgb(0,252,0)`
   */
  lightgreen: '\u00039',
  /**
   * IRC cyan `rgb(0,147,147)`
   */
  cyan: '\u000310',
  /**
   * IRC light cyan `rgb(0,255,255)`
   */
  lightcyan: '\u000311',
  /**
   * IRC light blue `rgb(0,0,252)`
   */
  lightblue: '\u000312',
  /**
   * IRC pink `rgb(255,0,255)`
   */
  pink: '\u000313',
  /**
   * IRC grey `rgb(127,127,127)`
   */
  grey: '\u000314',
  /**
   * IRC light grey `rgb(210,210,210)`
   */
  lightgrey: '\u000315',
};

/**
 * ^O character, color reset character
 */
export const IRC_FMT_RESET = '\u000F';

export const IRC_FMT_FORMAT_MAP = {
  /**
   * Normal text
   */
  normal: '\u0000',
  /**
   * <ins>underline text</ins>, `^_`
   */
  underline: '\u001F',
  /**
   * **bold text**, `^B`
   */
  bold: '\u0002',
  /**
   * *italic text*, `^I`
   */
  italics: '\u001D',
  /**
   * reverse color text, `^V`
   */
  reverse: '\u0016',
};

/**
 * Remove color and format characters from a string.
 * @param str Text
 * @returns Stripped text
 */
export const stripFormatting = (str: string): string =>
  str.replace(/(\x03\d{0,2}(,\d{0,2})?)/g, '').replace(/[\x00-\x1F]/g, '');

/**
 * Colorize a string for sending.
 * @param color IRC color key
 * @param str Text to colorize
 * @returns Text with control characters
 */
export const applyTextColor = (
  color: keyof typeof IRC_FMT_COLOR_MAP,
  str: string,
): string =>
  !IRC_FMT_COLOR_MAP[color]
    ? str
    : `${IRC_FMT_COLOR_MAP[color]}${str}${IRC_FMT_RESET}`;

/**
 * Apply text formatting to a string for sending.
 * @param format IRC format key
 * @param str Text to format
 * @returns Text with control characters
 */
export const applyTextFormat = (
  format: keyof typeof IRC_FMT_FORMAT_MAP,
  str: string,
): string =>
  !IRC_FMT_FORMAT_MAP[format]
    ? str
    : `${IRC_FMT_FORMAT_MAP[format]}${str}${IRC_FMT_RESET}`;

/**
 * Apply CTCP control characters with a command.
 * @param message Message
 * @param command CTCP command, e.g. `ACTION`
 * @returns Text with control characters
 */
export const applyCTCP = (message: string, command = 'ACTION') =>
  `\x01${command.toUpperCase()} ${message}\x01`;

const styleCheckRe = /[\x00-\x1F]/;
const backRe = /^(\d{1,2})(,(\d{1,2}))?/;
const colourKey = '\x03';
const colourRe = /\x03/g;
const colorKeys = Object.keys(IRC_FMT_COLOR_MAP);
const fmtRegex: [string, RegExp][] = Object.keys(IRC_FMT_FORMAT_MAP).map(
  (key) => {
    const escaped = encodeURI(
      (IRC_FMT_FORMAT_MAP as Record<string, string>)[key],
    ).replace('%', '\\x');
    return [key, new RegExp(escaped + '(.*?)(' + escaped + '|$)')];
  },
);

export type IRCTextFormatWrapperFn = (
  text: string,
  foregroundColor?: string,
  backgroundColor?: string,
  textFormat?: string,
) => string;

const wrap: IRCTextFormatWrapperFn = (text, fg, bg, fmt) =>
  `<format${fg ? ` color="${fg}"` : ''}${bg ? ` background="${bg}"` : ''}${
    fmt ? ` text="${fmt}"` : ''
  }>${text}</format>`;

/**
 * Wrap regions of text that have formatting or colors with a custom wrapper, e.g. HTML.
 * Defaults to a psuedo-XML style wrapper `<format color background text />`
 * @param line Text with control characters
 * @param wrapperFn Wrapper function to use
 * @returns Text with applied wrappers
 */
export function wrapFormattedText(line: string, wrapperFn = wrap): string {
  // Recheck
  if (!styleCheckRe.test(line)) return line;

  // split up by the irc style break character ^O
  if (line.indexOf(IRC_FMT_RESET) >= 0) {
    return line
      .split(IRC_FMT_RESET)
      .map((value) => wrapFormattedText(value, wrapperFn))
      .join('');
  }

  let result = line;
  const parseArr = result.split(colourKey);

  for (let i = 0; i < parseArr.length; i++) {
    const text = parseArr[i];
    const match = text.match(backRe);
    const colour = match && colorKeys[+match[1]];
    let background = '';

    if (!match || !colour) {
      // ^C (no colour) ending. Escape current colour and carry on
      background = '';
      continue;
    }

    // set the background colour
    // we don't override the background local var to support nesting
    if (colorKeys[+match[3]]) {
      background = colorKeys[+match[3]];
    }

    // update the parsed text result
    result = result.replace(
      colourKey + text,
      wrapperFn(text.slice(match[0].length), colour, background),
    );
  }

  // Matching styles (italics/bold/underline)
  // if only colors were this easy...
  fmtRegex.forEach(function ([style, keyregex]) {
    if (result.indexOf(style) < 0) return;
    result = result.replace(keyregex, (match, text) =>
      wrapperFn(text, undefined, undefined, style),
    );
  });

  // replace the reminent colour terminations and be done with it
  return result.replace(colourRe, '');
}