ninwa/libs/logger.js

const config = require('../config.json');
const moment = require('moment');

// constants
const LOG_PREFIX_DEBUG = 'debug';
const LOG_PREFIX_INFO = 'info';
const LOG_PREFIX_WARNING = 'warning';
const LOG_PREFIX_ERROR = 'error';
const LOGLEVEL_DEBUG = 0;
const LOGLEVEL_INFO = 1;
const LOGLEVEL_WARNING = 2;
const LOGLEVEL_ERROR = 3;

// set loglevel on 'require'
const loglevel = function () {
    switch (config.log.level) {
        case LOG_PREFIX_DEBUG:
        case LOGLEVEL_DEBUG:
            return LOGLEVEL_DEBUG;
        case LOG_PREFIX_INFO:
        case LOGLEVEL_INFO:
            return LOGLEVEL_INFO;
        case LOG_PREFIX_WARNING:
        case LOGLEVEL_WARNING:
            return LOGLEVEL_WARNING;
        case LOG_PREFIX_ERROR:
        case LOGLEVEL_ERROR:
            return LOGLEVEL_ERROR;
        default:
            return LOGLEVEL_INFO;
    }
}();

// prefix log with 'info'
function info(message) {
    if (loglevel > LOGLEVEL_INFO) {
        return;
    }
    trace(message);
}

// prefix log with 'info'
function warn(message) {
    if (loglevel > LOGLEVEL_WARNING) {
        return;
    }
    trace(message, 'warning');
}

// prefix log with 'debug'
function debug(message) {
    if (loglevel > LOGLEVEL_DEBUG) {
        return;
    }
    trace(message, 'debug');
}

// prefix log with 'error'
function error(message) {
    if (loglevel > LOGLEVEL_ERROR) {
        return;
    }
    trace(message, 'error');
}

// default logging function
function trace(message, prefix) {
    if (message === undefined || message === null || message.length === 0) {
        return;
    }
    if (prefix === undefined || prefix === null || prefix.length === 0) {
        prefix = 'info';
    }
    let print;
    switch (prefix) {
        case 'error':
            print = console.error;
            break;
        case 'debug':
            print = console.debug;
            break;
        case 'warning':
            print = console.warn;
            break;
        default:
            print = console.log;
    }
    message = moment().format(config.log.timestamp) + ' | ' + prefix + ' > ' + message;
    print(message);
}

// exports
module.exports = {
    info,
    warn,
    debug,
    error
};