[rbdr/cologne] / lib / formatters / token.js

'use strict';

const Utilities = require('../utilities');

/**
 * Token formatter. Given a format string it will attempt to output
 * a message.
 *
 * @memberof Formatters
 * @implements IFormatter
 * @class Token
 */
module.exports = class TokenFormatter {
  constructor(config) {

    /**
     * The string to use as a template string. By default, any property
     * inside double curly braces `{{likeThis}}` will be extracted from
     * the object and replaced. If the object does not contain the
     * property, it will leave it.
     *
     * @name formatString
     * @instance
     * @memberof Formatters.Token
     * @type String
     * @default '{{message}}'
     */
    this.formatString = '{{message}}';

    /**
     * The regex rule to use to match the tokens.
     *
     * @name replaceRule
     * @instance
     * @memberof Formatters.Token
     * @type RegExp
     * @default /{{(.{1,255}?)}}/g
     */
    this.replaceRule = /{{(.{1,255}?)}}/g;

    /**
     * Flag that specifies whether or not to use an isoDate when using
     * `_timestamp`. If false it will output the raw timestamp.
     *
     * @name isoDate
     * @instance
     * @memberof Formatters.Token
     * @type Boolean
     * @default true
     */
    this.isoDate = true;

    this._ansiRe = /_ansi:.+/;

    Object.assign(this, config || {});
  }

  /**
   * Main entry point, it will read the incoming log object and convert
   * all the tokens to their corresponding representation, finally
   * returning the string.
   *
   * @function format
   * @instance
   * @memberof Formatters.Token
   * @param {tCologneLog} log the log to format
   * @return {String} the formatted object
   */
  format(log) {

    const escapeCode = String.fromCharCode(27);
    return this.formatString.replace(this.replaceRule, (match, token) => {

      if (token === '_timestamp' && this.isoDate) {
        const date = new Date(Number(log._timestamp) / 1000000);
        return date.toISOString();
      }

      if (token.match(this._ansiRe)) {
        const ansiType = token.split(':')[1];

        // Smartish coloring
        if (ansiType === '_level') {
          return escapeCode + Utilities.getAnsiCode(Utilities.getLevelAnsi(log._level));
        }

        return escapeCode + Utilities.getAnsiCode(ansiType);
      }

      return log[token] || match;
    });
  }
};