logger.js
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var util = require('util');
var _ = require('lodash');
var loggerInstance;
var defaultProvider = {
log: console.log,
debug: console.log, // use .log(); since console does not have .debug()
info: console.info,
warn: console.warn,
error: console.error
};
// log level 'weight'
var LEVELS = {
debug: 10,
info: 20,
warn: 30,
error: 50,
silent: 80
};
module.exports = {
// singleton
getInstance: function() {
if (!loggerInstance) {
loggerInstance = new Logger();
}
return loggerInstance;
},
getArrow: getArrow
};
function Logger() {
var logLevel;
var provider;
var api = {
log: log,
debug: debug,
info: info,
warn: warn,
error: error,
setLevel: function(v) {
if (isValidLevel(v)) {
logLevel = v;
}
},
setProvider: function(fn) {
if (fn && isValidProvider(fn)) {
provider = fn(defaultProvider);
}
}
};
init();
return api;
function init() {
api.setLevel('info');
api.setProvider(function() {
return defaultProvider;
});
}
// log will log messages, regardless of logLevels
function log() {
provider.log(_interpolate.apply(null, arguments));
}
function debug() {
if (_showLevel('debug')) {
provider.debug(_interpolate.apply(null, arguments));
}
}
function info() {
if (_showLevel('info')) {
provider.info(_interpolate.apply(null, arguments));
}
}
function warn() {
if (_showLevel('warn')) {
provider.warn(_interpolate.apply(null, arguments));
}
}
function error() {
if (_showLevel('error')) {
provider.error(_interpolate.apply(null, arguments));
}
}
/**
* Decide to log or not to log, based on the log levels 'weight'
* @param {String} showLevel [debug, info, warn, error, silent]
* @return {Boolean}
*/
function _showLevel(showLevel) {
var result = false;
var currentLogLevel = LEVELS[logLevel];
if (currentLogLevel && (currentLogLevel <= LEVELS[showLevel])) {
result = true;
}
return result;
}
// make sure logged messages and its data are return interpolated
// make it possible for additional log data, such date/time or custom prefix.
function _interpolate() {
var fn = _.spread(util.format);
var result = fn(_.slice(arguments));
return result;
}
function isValidProvider(fnProvider) {
var result = true;
if (fnProvider && !_.isFunction(fnProvider)) {
throw new Error('[HPM] Log provider config error. Expecting a function.');
}
return result;
}
function isValidLevel(levelName) {
var validLevels = _.keys(LEVELS);
var isValid = _.includes(validLevels, levelName);
if (!isValid) {
throw new Error('[HPM] Log level error. Invalid logLevel.');
}
return isValid;
}
}
/**
* -> normal proxy
* => router
* ~> pathRewrite
* ≈> router + pathRewrite
*/
function getArrow(originalPath, newPath, originalTarget, newTarget) {
var arrow = ['>'];
var isNewTarget = (originalTarget !== newTarget); // router
var isNewPath = (originalPath !== newPath); // pathRewrite
if (isNewPath && !isNewTarget) {arrow.unshift('~');} else if (!isNewPath && isNewTarget) {arrow.unshift('=');} else if (isNewPath && isNewTarget) {arrow.unshift('≈');} else {arrow.unshift('-');}
return arrow.join('');
}