/* vim:set ts=2 sw=2 sts=2 expandtab */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

// Instead of inheriting from `Object.prototype` we copy all interesting
// properties from it and then freeze. This way we can guarantee integrity
// of components build on top.
exports.Base = Object.freeze(Object.create(null, {
  toString: { value: Object.prototype.toString },
  toLocaleString: { value: Object.prototype.toLocaleString },
  toSource: { value: Object.prototype.toSource },
  valueOf: { value: Object.prototype.valueOf },
  isPrototypeOf: { value: Object.prototype.isPrototypeOf },
  /**
   * Creates an object that inherits from `this` object (Analog of
   * `new Object()`).
   * @examples
   *
   *    var Dog = Base.extend({
   *      bark: function bark() {
   *        return 'Ruff! Ruff!'
   *      }
   *    });
   *    var dog = Dog.new();
   */
  new: { value: function create() {
    var object = Object.create(this);
    object.initialize.apply(object, arguments);
    return object;
  }},
  /**
   * When new instance of the this prototype is created it's `initialize`
   * method is called with all the arguments passed to the `new`. You can
   * override `initialize` to set up an instance.
   */
  initialize: { value: function initialize() {
  }},
  /**
   * Merges all the properties of the passed objects into `this` instance (This
   * method can be used on instances only as prototype objects are frozen).
   *
   * If two or more argument objects have own properties with the same name,
   * the property is overridden, with precedence from right to left, implying,
   * that properties of the object on the left are overridden by a same named
   * property of the object on the right.
   *
   * @examples
   *
   *    var Pet = Dog.extend({
   *      initialize: function initialize(options) {
   *        // this.name = options.name -> would have thrown (frozen prototype)
   *        this.merge(options) // will override all properties.
   *      },
   *      call: function(name) {
   *        return this.name === name ? this.bark() : ''
   *      },
   *      name: null
   *    })
   *    var pet = Pet.new({ name: 'Benzy', breed: 'Labrador' })
   *    pet.call('Benzy')   // 'Ruff! Ruff!'
   */
  merge: { value: function merge() {
    var descriptor = {};
    Array.prototype.forEach.call(arguments, function (properties) {
      Object.getOwnPropertyNames(properties).forEach(function(name) {
        descriptor[name] = Object.getOwnPropertyDescriptor(properties, name);
      });
    });
    Object.defineProperties(this, descriptor);
    return this;
  }},
  /**
   * Takes any number of argument objects and returns frozen, composite object
   * that inherits from `this` object and combines all of the own properties of
   * the argument objects. (Objects returned by this function are frozen as
   * they are intended to be used as types).
   *
   * If two or more argument objects have own properties with the same name,
   * the property is overridden, with precedence from right to left, implying,
   * that properties of the object on the left are overridden by a same named
   * property of the object on the right.
   * @examples
   *
   *    // ## Object composition ##
   *
   *    var HEX = Base.extend({
   *      hex: function hex() {
   *        return '#' + this.color;
   *      }
   *    })
   *
   *    var RGB = Base.extend({
   *      red: function red() {
   *        return parseInt(this.color.substr(0, 2), 16);
   *      },
   *      green: function green() {
   *        return parseInt(this.color.substr(2, 2), 16);
   *      },
   *      blue: function blue() {
   *        return parseInt(this.color.substr(4, 2), 16);
   *      }
   *    })
   *
   *    var CMYK = Base.extend(RGB, {
   *      black: function black() {
   *        var color = Math.max(Math.max(this.red(), this.green()), this.blue());
   *        return (1 - color / 255).toFixed(4);
   *      },
   *      cyan: function cyan() {
   *        var K = this.black();
   *        return (((1 - this.red() / 255).toFixed(4) - K) / (1 - K)).toFixed(4);
   *      },
   *      magenta: function magenta() {
   *        var K = this.black();
   *        return (((1 - this.green() / 255).toFixed(4) - K) / (1 - K)).toFixed(4);
   *      },
   *      yellow: function yellow() {
   *        var K = this.black();
   *        return (((1 - this.blue() / 255).toFixed(4) - K) / (1 - K)).toFixed(4);
   *      }
   *    })
   *
   *    var Color = Base.extend(HEX, RGB, CMYK, {
   *      initialize: function Color(color) {
   *        this.color = color;
   *      }
   *    });
   *
   *    // ## Prototypal inheritance ##
   *
   *    var Pixel = Color.extend({
   *      initialize: function Pixel(x, y, hex) {
   *        Color.initialize.call(this, hex);
   *        this.x = x;
   *        this.y = y;
   *      },
   *      toString: function toString() {
   *        return this.x + ':' + this.y + '@' + this.hex();
   *      }
   *    });
   *
   *    var pixel = Pixel.new(11, 23, 'CC3399')
   *    pixel.toString(); // 11:23@#CC3399
   *
   *    pixel.red();      // 204
   *    pixel.green();    // 51
   *    pixel.blue();     // 153
   *
   *    pixel.cyan();     // 0.0000
   *    pixel.magenta();  // 0.7500
   *    pixel.yellow();   // 0.2500
   *
   */
   extend: { value: function extend() {
    return Object.freeze(this.merge.apply(Object.create(this), arguments));
  }}
}));

/**
 * Function takes prototype object that implements `initialize` method, and
 * returns `constructor` function (with correct prototype property), that can
 * be used for simulating classes for given prototypes.
 */
exports.Class = Object.freeze(function Class(prototype) {
  function constructor() {
    var instance = Object.create(prototype);
    prototype.initialize.apply(instance, arguments);
    return instance;
  }
  return Object.freeze(Object.defineProperties(constructor, {
    prototype: { value: prototype },
    new: { value: constructor }
  }));
});