@lexamica-modules/logger/src/formatting.ts

The various loggers and transports used for API logging in the Lexamica Eco-system

import winston from 'winston';

// have to use any here since morgan does not make its types available
export function requestFormatter(tokens: any, req: any, res: any) {
  return JSON.stringify({
    method: tokens.method(req, res),
    url: tokens.url(req, res),
    status_code: Number.parseFloat(tokens.status(req, res)),
    content_length: tokens.res(req, res, 'content-length'),
    response_time: Number.parseFloat(tokens['response-time'](req, res)),
  });
}

function logFormatTemplate(line: {
  level: string;
  message: string;
  timestamp?: string;
  label?: string;
  metadata?: {
    timestamp?: string;
    label?: string;
  };
  [key: string]: unknown;
}): string {
  const {
    timestamp = new Date().toISOString(),
    label = 'logger',
    ...meta
  } = line.metadata || line || {};
  const metaEmpty =
    Object.keys(meta).length === 0 && meta.constructor === Object;
  const metaString = metaEmpty ? '' : JSON.stringify(meta, null, 2);
  return `${timestamp} [${label}] ${line.level}: ${line.message} ${metaString}`;
}

const jsonToString = winston.format((entry) => {
  const { message } = entry || {};
  if (message instanceof Map || message instanceof Set) {
    entry.message = `Map/Set keys: ${[...message.keys()].join(',')}`;
    return entry;
  } else if (typeof message === 'object') {
    entry.message = JSON.stringify(message);
    return entry;
  }
  return entry;
});

const colorFormat = winston.format.combine(
  jsonToString(),
  winston.format.timestamp(),
  winston.format.colorize(),
  winston.format.splat(),
  winston.format.simple(),
  winston.format.metadata(),
  winston.format.printf(logFormatTemplate)
);

const jsonFormat = winston.format.combine(
  jsonToString(),
  winston.format.timestamp(),
  winston.format.splat(),
  winston.format.simple(),
  winston.format.metadata(),
  winston.format.json()
);

export const getFormat = (formatType: 'color' | 'json') => {
  switch (formatType) {
    case 'color':
      return colorFormat;
    case 'json':
    default:
      return jsonFormat;
  }
};