text: /**
   * @author       Richard Davey <rich@photonstorm.com>
   * @copyright    2018 Photon Storm Ltd.
   * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
   */
  
  var Class = require('../../utils/Class');
  var CONST = require('../const');
  var FileTypesManager = require('../FileTypesManager');
  var JSONFile = require('./JSONFile.js');
  
  /**
   * @typedef {object} Phaser.Loader.FileTypes.PackFileConfig
   *
   * @property {string} key - The key of the file. Must be unique within both the Loader and the JSON Cache.
   * @property {string|any} [url] - The absolute or relative URL to load the file from. Or can be a ready formed JSON object, in which case it will be directly processed.
   * @property {string} [extension='json'] - The default file extension to use if no url is provided.
   * @property {string} [dataKey] - If specified instead of the whole JSON file being parsed, only the section corresponding to this property key will be added. If the property you want to extract is nested, use periods to divide it.
   * @property {XHRSettingsObject} [xhrSettings] - Extra XHR Settings specifically for this file.
   */
  
  /**
   * @classdesc
   * A single JSON Pack File suitable for loading by the Loader.
   *
   * These are created when you use the Phaser.Loader.LoaderPlugin#pack method and are not typically created directly.
   * 
   * For documentation about what all the arguments and configuration options mean please see Phaser.Loader.LoaderPlugin#pack.
   *
   * @class PackFile
   * @extends Phaser.Loader.File
   * @memberof Phaser.Loader.FileTypes
   * @constructor
   * @since 3.7.0
   *
   * @param {Phaser.Loader.LoaderPlugin} loader - A reference to the Loader that is responsible for this file.
   * @param {(string|Phaser.Loader.FileTypes.JSONFileConfig)} key - The key to use for this file, or a file configuration object.
   * @param {string} [url] - The absolute or relative URL to load this file from. If undefined or `null` it will be set to `<key>.json`, i.e. if `key` was "alien" then the URL will be "alien.json".
   * @param {XHRSettingsObject} [xhrSettings] - Extra XHR Settings specifically for this file.
   * @param {string} [dataKey] - When the JSON file loads only this property will be stored in the Cache.
   */
  var PackFile = new Class({
  
      Extends: JSONFile,
  
      initialize:
  
      //  url can either be a string, in which case it is treated like a proper url, or an object, in which case it is treated as a ready-made JS Object
      //  dataKey allows you to pluck a specific object out of the JSON and put just that into the cache, rather than the whole thing
  
      function PackFile (loader, key, url, xhrSettings, dataKey)
      {
          JSONFile.call(this, loader, key, url, xhrSettings, dataKey);
  
          this.type = 'packfile';
      },
  
      /**
       * Called automatically by Loader.nextFile.
       * This method controls what extra work this File does with its loaded data.
       *
       * @method Phaser.Loader.FileTypes.PackFile#onProcess
       * @since 3.7.0
       */
      onProcess: function ()
      {
          if (this.state !== CONST.FILE_POPULATED)
          {
              this.state = CONST.FILE_PROCESSING;
  
              this.data = JSON.parse(this.xhrLoader.responseText);
          }
  
          //  Let's pass the pack file data over to the Loader ...
          this.loader.addPack(this.data, this.config);
  
          this.onProcessComplete();
      }
  
  });
  
  /**
   * Adds a JSON File Pack, or array of packs, to the current load queue.
   *
   * You can call this method from within your Scene's `preload`, along with any other files you wish to load:
   * 
   * ```javascript
   * function preload ()
   * {
   *     this.load.pack('level1', 'data/Level1Files.json');
   * }
   * ```
   *
   * A File Pack is a JSON file (or object) that contains details about other files that should be added into the Loader.
   * Here is a small example:
   *
   * ```json
   * { 
   *    "test1": {
   *        "files": [
   *            {
   *                "type": "image",
   *                "key": "taikodrummaster",
   *                "url": "assets/pics/taikodrummaster.jpg"
   *            },
   *            {
   *                "type": "image",
   *                "key": "sukasuka-chtholly",
   *                "url": "assets/pics/sukasuka-chtholly.png"
   *            }
   *        ]
   *    },
   *    "meta": {
   *        "generated": "1401380327373",
   *        "app": "Phaser 3 Asset Packer",
   *        "url": "https://phaser.io",
   *        "version": "1.0",
   *        "copyright": "Photon Storm Ltd. 2018"
   *    }
   * }
   * ```
   *
   * The pack can be split into sections. In the example above you'll see a section called `test1. You can tell
   * the `load.pack` method to parse only a particular section of a pack. The pack is stored in the JSON Cache,
   * so you can pass it to the Loader to process additional sections as needed in your game, or you can just load
   * them all at once without specifying anything.
   *
   * The pack file can contain an entry for any type of file that Phaser can load. The object structures exactly
   * match that of the file type configs, and all properties available within the file type configs can be used
   * in the pack file too.
   *
   * The file is **not** loaded right away. It is added to a queue ready to be loaded either when the loader starts,
   * or if it's already running, when the next free load slot becomes available. This happens automatically if you
   * are calling this from within the Scene's `preload` method, or a related callback. Because the file is queued
   * it means you cannot use the file immediately after calling this method, but must wait for the file to complete.
   * The typical flow for a Phaser Scene is that you load assets in the Scene's `preload` method and then when the
   * Scene's `create` method is called you are guaranteed that all of those assets are ready for use and have been
   * loaded.
   * 
   * If you call this from outside of `preload` then you are responsible for starting the Loader afterwards and monitoring
   * its events to know when it's safe to use the asset. Please see the Phaser.Loader.LoaderPlugin class for more details.
   * 
   * The key must be a unique String. It is used to add the file to the global JSON Cache upon a successful load.
   * The key should be unique both in terms of files being loaded and files already present in the JSON Cache.
   * Loading a file using a key that is already taken will result in a warning. If you wish to replace an existing file
   * then remove it from the JSON Cache first, before loading a new one.
   *
   * Instead of passing arguments you can pass a configuration object, such as:
   * 
   * ```javascript
   * this.load.pack({
   *     key: 'level1',
   *     url: 'data/Level1Files.json'
   * });
   * ```
   *
   * See the documentation for `Phaser.Loader.FileTypes.PackFileConfig` for more details.
   *
   * If you have specified a prefix in the loader, via `Loader.setPrefix` then this value will be prepended to this files
   * key. For example, if the prefix was `LEVEL1.` and the key was `Waves` the final key will be `LEVEL1.Waves` and
   * this is what you would use to retrieve the text from the JSON Cache.
   *
   * The URL can be relative or absolute. If the URL is relative the `Loader.baseURL` and `Loader.path` values will be prepended to it.
   *
   * If the URL isn't specified the Loader will take the key and create a filename from that. For example if the key is "data"
   * and no URL is given then the Loader will set the URL to be "data.json". It will always add `.json` as the extension, although
   * this can be overridden if using an object instead of method arguments. If you do not desire this action then provide a URL.
   *
   * You can also optionally provide a `dataKey` to use. This allows you to extract only a part of the JSON and store it in the Cache,
   * rather than the whole file. For example, if your JSON data had a structure like this:
   * 
   * ```json
   * {
   *     "level1": {
   *         "baddies": {
   *             "aliens": {},
   *             "boss": {}
   *         }
   *     },
   *     "level2": {},
   *     "level3": {}
   * }
   * ```
   *
   * And you only wanted to store the `boss` data in the Cache, then you could pass `level1.baddies.boss`as the `dataKey`.
   *
   * Note: The ability to load this type of file will only be available if the Pack File type has been built into Phaser.
   * It is available in the default build but can be excluded from custom builds.
   *
   * @method Phaser.Loader.LoaderPlugin#pack
   * @fires Phaser.Loader.LoaderPlugin#addFileEvent
   * @since 3.7.0
   *
   * @param {(string|Phaser.Loader.FileTypes.PackFileConfig|Phaser.Loader.FileTypes.PackFileConfig[])} key - The key to use for this file, or a file configuration object, or array of them.
   * @param {string} [url] - The absolute or relative URL to load this file from. If undefined or `null` it will be set to `<key>.json`, i.e. if `key` was "alien" then the URL will be "alien.json".
   * @param {string} [dataKey] - When the JSON file loads only this property will be stored in the Cache.
   * @param {XHRSettingsObject} [xhrSettings] - An XHR Settings configuration object. Used in replacement of the Loaders default XHR Settings.
   *
   * @return {Phaser.Loader.LoaderPlugin} The Loader instance.
   */
  FileTypesManager.register('pack', function (key, url, packKey, xhrSettings)
  {
      //  Supports an Object file definition in the key argument
      //  Or an array of objects in the key argument
      //  Or a single entry where all arguments have been defined
  
      if (Array.isArray(key))
      {
          for (var i = 0; i < key.length; i++)
          {
              this.addFile(new PackFile(this, key[i]));
          }
      }
      else
      {
          this.addFile(new PackFile(this, key, url, xhrSettings, packKey));
      }
  
      return this;
  });
  
  module.exports = PackFile;
  