index.js

'use strict'

const chalk = require('chalk')
const prettyjson = require('prettyjson')
const safeStringify = require('fast-safe-stringify')
const DateFormat = require('fast-date-format')
const dateFormat = new DateFormat('YYYY-MM-DD HH:mm:ss')

const options = {
  keysColor: 'yellow',
  stringColor: 'green',
  numberColor: 'red'
}

class Logger {
  constructor (name, options = {}) {
    if (typeof name !== 'string' || name === '') {
      throw new Error('You must supply a name when creating a logger.')
    }

    this.name = name.toUpperCase()
    this.level = options.level || 'trace'
    this.throwOnError = options.throwOnError || false // Exit when error occures, be careful if you exit early not all errors are printed
    this.colorEntireLine = options.colorEntireLine || false // color the entire log line, if set to false only meta will be colored
    this.levels = ['trace', 'debug', 'info', 'warn', 'error', 'off']
    this.colors = ['grey', 'cyan', 'greenBright', 'yellowBright', 'red', 'grey']
  }

  _getColor (level) {
    return this.colors[this.levels.indexOf(level)]
  }

  _shouldPrint (level) {
    return this.levels.indexOf(level) >= this.levels.indexOf(this.level)
  }

  _write (name, level, msgs) {
    if (this._shouldPrint(level)) {
      let logLine = ''

      for (const msg of msgs) {
        // Do not stringify Error instances
        if (msg instanceof Error) {
          logLine += '\n ' + msg.stack
          continue
        }
        if (typeof msg === 'object') {
          logLine += ' ' + safeStringify(msg)
          continue
        }

        logLine += ' ' + msg
      }

      const color = this._getColor(level)

      const levelStr = level.toUpperCase()

      const timestamp = dateFormat.format() // It will take current timestamp is no date is passed

      const meta = `${timestamp} [${levelStr}] [${name}]`

      let finalString = chalk[color](meta) + `${logLine}`

      if (this.colorEntireLine) {
        finalString = chalk[color](`${meta} ${logLine}`)
      }

      console.log(finalString) // for further extreme performance, write directly to stdout. (aware of the formatting tradeoffs)

      // process.stdout.write(finalString + '\n');
    }
  }

  setLogLevel (level) {
    this.level = level.toLowerCase()
    return this
  }

  getLogLevel () {
    return this.level
  }

  error (...msgs) {
    this._write(this.name, this.error.name, msgs)

    if (this.throwOnError) {
      throw new Error(msgs)
    }
  }

  warn (...msgs) {
    this._write(this.name, this.warn.name, msgs)
  }

  info (...msgs) {
    this._write(this.name, this.info.name, msgs)
  }

  debug (...msgs) {
    this._write(this.name, this.debug.name, msgs)
  }

  trace (...msgs) {
    this._write(this.name, this.trace.name, msgs)
  }

  // Pretty print, for debugging, not performant
  pp (obj) {
    console.log(prettyjson.render(obj, options))
  }
}

module.exports = Logger