im/util/log.js

"use strict";

(function () {
    var util = require('util');

    // log level
    var LEVEL = {
        ALL:Infinity,
        INFO:3,
        WARN:2,
        ERROR:1,
        NONE:-Infinity
    };

    // log color
    var COLOR = {
        RESET:'\u001b[0m',
        INFO:'\u001b[32m', // green
        WARN:'\u001b[33m', // yellow
        ERROR:'\u001b[31m' // red
    };

    // global log level
    var globalLevel = LEVEL.ALL;

    // whether log output should be colored
    var coloredOutput = true;

    function setLevel(level) {
        globalLevel = level;
    }

    function setColoredOutput(bool) {
        coloredOutput = bool;
    }

    function info() {
        if (LEVEL.INFO <= globalLevel) {
            log(LEVEL.INFO, util.format.apply(this, arguments));
        }
    }

    function warn() {
        if (LEVEL.WARN <= globalLevel) {
            log(LEVEL.WARN, util.format.apply(this, arguments));
        }
    }

    function error() {
        if (LEVEL.ERROR <= globalLevel) {
            log(LEVEL.ERROR, util.format.apply(this, arguments));
        }
    }

    function newPrepareStackTrace(error, structuredStack) {
        return structuredStack;
    }

    // must not be called directly due to stack trace
    function log(level, message) {
        // get call stack and find the caller
        var oldPrepareStackTrace = Error.prepareStackTrace;
        Error.prepareStackTrace = newPrepareStackTrace;
        var structuredStack = new Error().stack;
        Error.prepareStackTrace = oldPrepareStackTrace;
        var caller = structuredStack[2];

        var lineSep = process.platform == 'win32' ? '\\' : '/';
        var fileNameSplited = caller.getFileName().split(lineSep);
        var fileName = fileNameSplited[fileNameSplited.length - 1];
        var lineNumber = caller.getLineNumber();
        var columnNumber = caller.getColumnNumber();
        // function name may be empty if it is a global call
        // var functionName = caller.getFunctionName();
        var levelString;
        switch (level) {
            case LEVEL.INFO:
                levelString = '[INFO]';
                break;
            case LEVEL.WARN:
                levelString = '[WARN]';
                break;
            case LEVEL.ERROR:
                levelString = '[ERROR]';
                break;
            default:
                levelString = '[]';
                break;
        }
        var output = util.format('%s %s(%d,%d): %s',
            levelString, fileName, lineNumber, columnNumber, message
        );
        if (!coloredOutput) {
            process.stdout.write(output + '\n');
        } else {
            switch (level) {
                case LEVEL.INFO:
                    process.stdout.write(COLOR.INFO + output + COLOR.RESET + '\n');
                    break;
                case LEVEL.WARN:
                    process.stdout.write(COLOR.WARN + output + COLOR.RESET + '\n');
                    break;
                case LEVEL.ERROR:
                    process.stdout.write(COLOR.ERROR + output + COLOR.RESET + '\n');
                    break;
                default:
                    break;
            }
        }
    }

    module.exports = {
        info:info,
        warn:warn,
        error:error,
        LEVEL:LEVEL,
        setLevel:setLevel,
        setColoredOutput:setColoredOutput
    };

}());