src/logger.js

/*
 * OS.js - JavaScript Cloud/Web Desktop Platform
 *
 * Copyright (c) Anders Evenrud <andersevenrud@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @author  Anders Evenrud <andersevenrud@gmail.com>
 * @license Simplified BSD License
 */

const methods = ['debug', 'log', 'info', 'warn', 'error'];
let middleware = [];

const reduce = (name, input) => middleware
  .reduce((current, m) => m(name, ...current), input);

const bind = (fn, thisArg) =>
  typeof thisArg[fn].bind === 'function'
    ? thisArg[fn].bind(thisArg)
    : Function.prototype.bind.apply(thisArg[fn], thisArg);

const bindMethod = fn => {
  const log = bind(fn, console);
  if (middleware.length > 0) {
    return (...args) => log(...reduce(fn, args));
  }

  return log;
};

const assignMethods = (thisArg) => methods
  .forEach(m => thisArg[m] = bindMethod(m));

const instance = {
  addMiddleware: m => {
    middleware.push(m);
    assignMethods(instance);
  },
  clearMiddleware: () => {
    middleware = [];
    assignMethods(instance);
  }
};

assignMethods(instance);

export default instance;