loggers/index.js

simple and powerfull loggers

module.exports = configure;

var _ = require("lodash"),
    u = configure.u = require("./utils"),
    loggerProxyHandler = {

        apply(logger, $this, args) {
            return logger("def", ...args);
        },

        get(logger, prop) {
            if(prop === "config") return logger.config;
            if(prop === "u") return u;
            return logger.bind(null, prop);
        }
    };

function configure(config) {
    // defaults
    if(!_.isPlainObject(config)) {
        let tmpl;
        if(_.isString(config)) {
            tmpl = config;
        } else {
            tmpl = "${logger}.${level}: ${message}\n"
        }
        config = {
            def: {
                def: u.tmplout(tmpl),
                err: u.tmplerr(tmpl)
            }
        }
    }

    var cache = {};
    return getLogger.bind(null, cache, config);
}

function getLogger(cache, config, loggerName) {
    return loggerName in cache ?
        cache[loggerName] :
        cache[loggerName] = newLogger(config, loggerName);
}

function newLogger(config, loggerName) {
    let logger = log.bind(null, config, loggerName),
        loggerProxy = new Proxy(logger, loggerProxyHandler);
    logger.config = config;
    return loggerProxy;
}

function log(config, loggerName, levelName, ...args) {
    let handlers = _.get(config, [loggerName, levelName]) ||
                   _.get(config, [loggerName, "def"]) ||
                   _.get(config, ["def", levelName]) ||
                   _.get(config, ["def", "def"]),
        record = new Record(...arguments);
    execHandler(record, handlers);
    
    return record;
}

class Record {
    // the same arguments as in the "log" function
    constructor(config, loggerName, levelName, ...args) {
        this.logger = loggerName;
        this.level = levelName;
        this.config = config;
        this.args = args;
        this.journal = {};
    };

    get u() {
        return u;
    }
    
    get filename() {
        
    }
}

function execHandler(record, handler) {
    if(_.isArray(handler)) {
        handler.some(execHandler.bind(null, record));
    }
    if(_.isFunction(handler)) {
        try {
            handler(record);
        } catch(err) {
            record.cause = err;
            return true;
        }
    }
    return false;
}