NodeJS | Module: Log | Logging utils.

log.js

/**
 * @module  Log
 * @desc    Logging utils.
 * @see     {@link https://gist.github.com/andresmatasuarez/66edcd9710986cca4c59| GitHub gist}
 * @author  Andrés Mata Suárez <amatasuarez@gmail>
 * @license {@link http://www.opensource.org/licenses/mit-license.php| MIT License}
 *
 * @requires {@link http://nodejs.org/api/util.html| util}
 * @requires {@link https://github.com/lorenwest/node-config| config}
 * @requires {@link https://github.com/winstonjs/winston| winston}
 *
 * @example
 * var Log = require('./log');
 *
 * Log.blankLine();
 *
 * Log.context('Custom context').info('Custom operation')();
 * Log.context('Custom context').error('Custom error')();
 *
 */

'use strict';

var util    = require('util');
var config  = require('config');
var winston = require('winston');

var largestContextLength = 0;
var logger               = new winston.Logger({
  transports: [
    new winston.transports.Console({ silent: config.logs && config.logs.silent })
  ]
});

function _padding(context){
  var spacesToFill = largestContextLength - context.length;
  return (spacesToFill !== 0 ? ' ' : '') + new Array(spacesToFill).join(' ');
}

function _log(type){
  return function(context, msg){
    return function(){
      var args = Array.prototype.slice.call(arguments);
      args.unshift(context + _padding(context) + ' | ' + msg);
      logger.log(type, util.format.apply(util, args));
    };
  };
}

function _context(context){
  context = context || '';
  largestContextLength = largestContextLength < context.length ? context.length : largestContextLength;
  return {
    info: function(msg){
      return _log('info')(context, msg);
    },
    error: function(msg){
      return _log('error')(context, msg);
    }
  };
}

module.exports = {

  context: _context,

  blankLine: _context().info(''),

  Repeat: {
    start          : _context('Repeat').info('Started task: %s.'),
    repeat         : _context('Repeat').info('Repeating task: %s...'),
    waiting        : _context('Repeat').info('Waiting %s millis before repeating task: %s.'),
    stop           : _context('Repeat').info('Stopped task: %s.'),
    alreadyStarted : _context('Repeat').info('Task already started: %s.'),
    alreadyStopped : _context('Repeat').info('Task already stopped: %s.'),
  }

};