onebeyond/generator-systemic

const chalk = require('chalk');
const hogan = require('hogan.js');
const R = require('ramda');

const response = hogan.compile(
  '{{{timestamp}}} | {{{displayLevel}}} [{{package.name}}] {{{displayTracer}}} {{{request.method}}} {{{response.statusCode}}} {{{request.url}}}',
);
const error = hogan.compile(
  '{{{timestamp}}} | {{{displayLevel}}} [{{package.name}}] {{{displayTracer}}} {{{errorMessage}}} {{{code}}}\n{{{error.stack}}} {{{details}}}',
);
const info = hogan.compile(
  '{{{timestamp}}} | {{{displayLevel}}} [{{package.name}}] {{{displayTracer}}} {{{message}}} {{{details}}}',
);

const colours = {
  debug: chalk.gray,
  info: chalk.white,
  warn: chalk.yellow,
  error: chalk.red,
  default: chalk.white,
};

module.exports = () => {
  const onMessage = event => {
    const details = R.pluck(event, []);
    const data = R.merge(event, {
      displayTracer: R.has('tracer', event) ? event.tracer.substr(0, 6) : '|',
      displayLevel: event.level.toUpperCase().padStart(event.level.length + Math.floor((6 - event.level.length) / 2), ' ')
        .padEnd(6, ' '),
      details: Object.keys(details).length ? `\n ${JSON.stringify(details, null, 2)}` : '',
      errorMessage:
                event.error
                && (event.error.message instanceof Object ? JSON.stringify(event.error.message) : event.error.message),
      timestamp: event.timestamp.toISOString(),
    });
    const colour = colours[event.level] || colours.default;
    // eslint-disable-next-line no-console
    const log = console[event.level] || console.info;
    if (R.has('response.statusCode', event)) log(colour(response.render(data)));
    else if (data.errorMessage) log(colour(error.render(data)));
    else log(colour(info.render(data)));
  };

  const start = async () => onMessage;

  return { start };
};