logger.js

/* global module */
let stack = require("callsite");
let winston = require("winston");
let path = require("path");

let formatter = function(options) {
    return options.level.toUpperCase() + " " +
        (options.message ? options.message : "") +
        (options.meta && Object.keys(options.meta).length ? "\n\t" + JSON.stringify(options.meta) : "");
};

module.exports = function(config) {
    if(!config || !config.transports || !config.levels || !config.level) {
        throw new Error("Invalid configuration.");
    }

    let logTransports = config.transports;

    let logOptions = {
        transports: [],
        levels: config.levels,
        level: config.level
    };

    logTransports.forEach(function(t) {
        switch (t.name) {
        case "console":
            logOptions.transports.push(new winston.transports.Console(t.options));
            break;
        case "syslog":
            t.options.timestamp = function() {
                return Date.now();
            };
            t.options.formatter = formatter;
            require("winston-syslog").Syslog;
            logOptions.transports.push(new winston.transports.Syslog(t.options));
            break;
        default:
            throw new Error("Unsupported transport.");
        }
    });

    let logger = new winston.Logger(logOptions);

    if(config.colors) {
        winston.addColors(config.colors);
    }

    var oldInfo = logger.info;
    logger.info = function(...args) {
        var site = stack()[1];
        args[0] = "[" + (site.getFunctionName() || "anonymous") + ":" + path.basename(site.getFileName()) +
            ":" + site.getLineNumber() + "] " + args[0];
        return oldInfo.apply(this, args);
    };
    var oldDebug = logger.debug;
    logger.debug = function(...args) {
        var site = stack()[1];
        args[0] = "[" + (site.getFunctionName() || "anonymous") + ":" + path.basename(site.getFileName()) +
        ":" + site.getLineNumber() + "] " + args[0];
        return oldDebug.apply(this, args);
    };

    return logger;
};